Flicker Reference Manual

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This reference manual undergos revision as the program develops. A short form of the manual will appear as a chapter in the upcoming 3rd edition of The Proteomics Handbook, John Walker (ed) to be published in 2004 [Lemkin2004].

The following summaries list some information on using the interactive controls to run the program. You interact with the Flicker program using the mouse movments, keyboard commands, checkboxes states, slider controls parameter values, and pull-down menus. Figure 1 shows a screen view of the Flicker program.


Screen view of Flicker program

Figure.1 Screen view of the Flicker program This screen shot shows the pull-down menus (A) at the top of the Flicker window used to invoke file operations, editing, view selection, landmarking, image transforms, spot quantification, and help commands. A set of scroll bars on the right determines various parameters used in some of the transforms. The File menu options include opening new gel images. Checkboxes on the left (B) activate flickering and active gel map access if the data supports it. A set of status lines (C) appear below the checkboxes and indicate the state of operation and various other messages. The flicker image (D) is in the upper-middle of the frame when it is enabled. The two labeled human blood plasma gel images are shown in the bottom left and right scrollable image windows (E) that may be positioned to the region of interest. These windows also have associated flicker time-delays (F) used when flickering. Image plasmaH is an IPG non-linear gradient gel from
SWISS-2DPAGE and plasmaL is a carrier-ampholyte linear gradient gel from the Merril Lab at NIMH. Transformed image results are shown in the same scrollable windows. The four checkboxes are: Flicker to enable/disable flickering; Click to access DB checkbox enables/disables access to a Web server that is associated with a clickable image DB if it exists for the selected image; Allow transforms checkbox enables/disables image transforms; Sequential transforms checkbox enables/disables using the last image transform output as input for the next image transform. Parameters are directly specified using sliders (G) to adjust zoom magnification, contrast, brightness, etc. A popup scrollable report window (not shown) logs all text output that appears in the status lines. You can popup the report window with the current scroller values by the Report scroller values button (H). This text may be saved to a text file on your local disk for printing or further analysis. The size of the three image canvases may be increased/decreased using the "+" / "-" buttons under the parameter scrollbars (H).



1. Flickering gel images

The basic concept of using flickering as a dynamic visualization technique is simple. If two images may be perfectly aligned then one could simply align them by overlaying one over the other and shifting one image until they line up. However, many images such as 2D PAGE gels have rubber-sheet distortion (i.e., local translation, rotation, and magnification - linear over short distances and non-linear over the entire gel). This means there is more distortion in some parts of the image than in others. Although it is often impossible to align the two whole images at one time, they may be locally aligned piece-by-piece by matching the morphology of local regions.

If it appears that a spot and the surrounding region do match, then one has more confidence that the objects are the same. This putative visual identification is our definition of matching when doing a comparison. Full identification of protein spots requires further work such as cutting spots out of the gels and subjecting them to sequence analysis, amino-acid composition analysis, mass spectrometry, testing them with monoclonal antibodies, or other methods.

1.1 Flickering

When flickering two images with the computer, one aligns putative corresponding subregions of the two rapidly alternating images. The flicker window overlays the same space on the screen with the two images and is aligned by interactively moving one image relative to the other using the cursor in either or both of the lower images. Enable the Flicker checkbox (Figure 1.B) to turn on flickering and disable it to shut it off.

Using the mouse, the user initially selects (by clicking on the image - left or right window) what they suspect is the same prominent spot or object in similar morphologic regions in the two gel images. If you click on the spot with the Control key pressed, it will center that image at that spot in the window and also center it in the flicker window. You can continuously adjust the position in the flicker window, without changing the selected window position, by selecting the image you want to recenter and draging the mosue. When these two local regions come into alignment, they appear to pulse and the images appear to fuse together. At this point, differences are more apparent and it is fairly easy to see which spots or objects correspond, which are different, and how they differ. We have found that the user should be positioned fairly close to the flicker window on the screen to optimize this image-fusion effect (i.e., it does not work as well standing back more than a few feet from the screen).

Another useful trick is change the image canvas size after doing the initial alignment. This may help you focus on a smaller region after you have done the rough alignment. You can either use the "+" / "-" buttons under the parameter scrollbars (Figure 1.I), or you can use the Control-keypad + and Control-keypad - keys.

1.2 Selecting the proper time delays when flickering

The proper flicker delays, or time each image is displayed on the screen, is critical for the optimal visual integration of image differences. We have also found that optimal flicker rates are dependent on a wide variety of factors including: amount of distortion, similarity of corresponding subregions, complexity and contrast of each image, phosphor decay time of the display, ambient light, distance from the display, individual viewer differences, etc. We have found the process of flickering images is easier for some people than for others.

When comparing a light spot in one gel with the putative paired darker spot in the other gel one may want to linger longer on the lighter spot to make a more positive identification. Because of this, we give the user the ability to set the display times independently for the two images (typically in the range of 0.01 second to 1.0 second with a default of 0.30 second) using separate Delay scroll bars located under each image (Figure 1.E). If the regions are complex and have a lot of variation, longer display times may be useful for both images. Differential flicker delays with a longer delay for the light gel are useful for comparing light and dark sample gels. This lets you stare at the lighter spots to have more verification that they are actually there.

These flicker delay values are saved for the left and right images when you save the Flicker state.

1.3 Mouse control of images

The following mouse and key-modified mouse operations control various actions.

a) A) Example - before adjusting image contrast of one image to the other
b) Example - after adjusting image contrast of one image to the other

Figure 2. Example of adjusting the image contrast on one image to match the overall contrast of the other. A) shows the original plasmaH and PlasmaL images before contrast adjustment b) shows the plasma images after the contrast was adjusted in the plasmaL image.

1.4 Lookup of putative spot identification on Swiss-2DPAGE

Protein spots may be putatively identified using active map images that link to federated 2D gel databases such as SWISS-2DPAGE. First, load an active map image for your type of biological material (if it can be found). Then flicker align the two gels around the spot(s) you are interested in. Then enable the Checkbox onClick to access DB checkbox. Then set the (View | Checkbox onUse protein DB browser, else lookup ID and name on active images) menu checkbox command is enabled. Finally, click on the spot of interest and this brings up the specific protein annotation page from the active DB server (in this case SWISS-2DPAGE) in a Web browser. Figure 3 shows an illustration of procedure.

In place of the Web browser, you can just have it report the Swiss-Prot ID and the protein name annotation from the Swiss-2DPAGE Web server. Set the (View | Checkbox offUse protein DB browser, else lookup ID and name on active images) menu checkbox command is disabled. Then when you click on a spot, it will now try to get the Swiss-Prot ID and the protein name by the spot's coordinates and display the results in your report window.

The next discussion describes looking up the (ID, protein names) for a set of spots you have defined.

Protein spots putatively identified from SWISS-2DPAGE DB

Figure 3. Protein spots may be putatively identified using active map images that link to federated 2D gel databases. First, load an active map image for you type of biological material (if it can be found). Then flicker align the two gels around the spot(s) you are interested in. Then enable the Checkbox onClick to access DB checkbox. Finally, click on the spot of interest and this brings up the Web page from the active DB server (in this case SWISS-2DPAGE). If the (View | Checkbox onUse protein DB browser, else lookup ID and name on active images) is enabled, then clicking on a spot will popup a Web browser with the associated database page (as is shown). If the checkbox is off, then it will get the data from that web page and report it. If you have defined a set of spots in a spot list in an active gel, the (Quantify | Measure by Circle | Lookup Protein IDs and Names from active map server (selected image)) menu command will try to lookup each spot in the list by its coordinates and will save the results (Swiss-Prot ID and protein name) as the spot annotation's (id,name).

1.4.1 Looking up and assigning putative spot IDs for lists of spots

If you have defined a set of spots in a spot list for an active gel, the (Quantify | Measure by Circle | Lookup Protein IDs and Names from active map server (selected image)) menu command will try to lookup each spot in the list by its coordinates and will save the results (Swiss-Prot ID and protein name) as the spot annotation's (id,name). Note that you must be connected to the Internet. After this lookup has finished (it may take a while), use the (Quantify | Measure by Circle | List spots in the spot list for selected image) to view the filled in table. The (C-Q) key-command may be use to stop the lookup procedure for a long list of spots after it finishes the current spot lookup.

If you then have a set of corresponding spots you have defined in your gel, you can then edit their annotation so it matches the reference gel that you just assigned putative spot identifications. This is described in the following Figures 3.1a through 3.1d You can lookup the protein (ID,names) for a set of spots you have defined in the active gel map image that is link to federated 2D gel databases. See the vignettes for query a spot's putative identity and assigning a spot's putative identity for more details.

 
a) Define a set of spots to measure

Figure 3.1a) First define a set of spots in the active gel (described under the
Quantify menu). You might want to view the spot annotations by setting the (View | Set view measurement options | Checkbox onUse 'spot identifier ' for spot annotations) menu checkbox. Then enable the Checkbox onClick to access DB checkbox. Then, if you are connected to the Internet, with the active gel selected, use the (Quantify | Measure by Circle | Lookup Protein IDs and Names from active map server (selected image)) menu command. This will try to lookup each spot in the list by its coordinates and will save the results (Swiss-Prot ID and protein name) in each the spots annotation's (id,name).

b) Spots in image after lookup identifiers

Figure 3.1b) Shows the updated spot list after the spots have been identified from the active reference gel database. Now disable the Checkbox offClick to access DB checkbox so that it does not popup the Web browser when you then click on the image.

c) Define a list of spots in other gel

Figure 3.1 c) Then define a list of spots in the other user gel by selecting the spot and typing (C-M). Repeat the following for each spot in the gel lists. First select a spot in the reference gel, and then select the corresponding spot in the user gel. Assign the same annotation to both by typing (C-I).

d) Copy annotation by 'Edit spot annotation'

Figure 3.1 d) This will popup "Edit spot annotation" window with the spot identifier from the reference gel. Just press the Done button and the annotation will be assigned to the user gel spot you are editing.

1.4.2 Accessing PIR UniProt, iProClass and iProLink server Web pages for selected proteins

You may optionally access PIR UniProt, iProClass and iProLink server Web pages for selected proteins in the spot list through their Swiss-Prot accession names. This is accomplished in a two-step process enabled using the (Edit | Select access to active DB server | Checkbox on ...) checkbox command. You may select either SWISS-2DPAGE, UniProt, iProClass or iProLink servers - or none of these. If you measure a spot (select a spot in an active image and then type C-M) (and are connected to the Internet), it will also lookup the Swiss-Prot protein (accession name, and protein id) on the SWISS-2DPAGE server. Then, if you enable "Click to access DB", it will pop up the particular active DB server you have selected. Figures 3.2a UniProt, 3.2b iProClass, and 3.2c iProLink.

An additional option that makes this easier to use is to enable the (Edit | Checkbox onAuto measure, protein lookup and Web page popup) checkbox command. Then when you click on a spot in an active image (associated with a Web database), it will: 1) measure the spot and add it to the spot list; 2) lookup the Swiss-Prot (name, id); and 3) pop up the Web server on the currently selected active DB server.

a) Image after accessing PIR UniProt ids

Figure 3.2a) Results of accessing PIR
UniProt server Web pages for protein 3 P02760 from Figure 3.1b. This was accessed using the method describe in section 1.4.2 above by enabling (Edit | Select access to active DB server | Checkbox onUse PIR UniProt DB access) checkbox command set, enabling (Edit | Checkbox offAuto measure, protein lookup and Web page popup) checkbox command, and then clicking on the spot.

b) RImage after accessing PIR iProClass server

Figure 3.2b) Results of accessing PIR
iProClass server Web pages for protein 3 P02760 from Figure 3.1b. This was accessed using the method describe in section 1.4.2 above by enabling (Edit | Select access to active DB server | Checkbox onUse PIR iProClass DB access) checkbox command set, enabling (Edit | Checkbox offAuto measure, protein lookup and Web page popup) checkbox command, and then clicking on the spot.

c) Result of accessing PIR iProLink server

Figure 3.2c) Results of accessing PIR
iProLink server Web pages for protein 3 P02760 from Figure 3.1b. This was accessed using the method describe in section 1.4.2 above by enabling (Edit | Select access to active DB server | Checkbox onUse PIR iProLink DB access) checkbox command set, enabling (Edit | Checkbox offAuto measure, protein lookup and Web page popup) checkbox command, and then clicking on the spot.

1.5 Checkbox control of flickering and database access

There are four checkboxes in the upper left part of the window (Figure 1.B) that control commonly used options. Figure 3 describes these options in more detail.


Flicker checkbox controls interface

Figure 4. Screen view of the Flicker checkbox controls. This shows the global checkbox controls that are used to set operational modes for flickering, Web database access and image processing transforms. These values are saved when you save the Flicker state.

2. Image enhancement prior to flickering - Transforms

It is well-known that 2D gels often suffer from local geometric distortions making perfect overlay impossible. Therefore, making the images locally morphologically similar while preserving their grayscale data may make them easier to compare. Even when the image subregions are well aligned, it is still sometimes difficult to compare images that are quite different. Enhancing the images using various image transforms before flickering may also help. The Transforms menu contains a number of image transforms. Click on the image you want to transform and then select the transform from the list of available transforms. If you select neither the left or right image, it will perform the transform on both images.

Some of these transforms involve spatial warping, which maps a local region of one image onto the geometry of the local region of another image while preserving its grayscale values. Another useful operation is contrast enhancement that helps when comparing light or dark regions by adjusting the dynamic range of image data to the dynamic range of the computer display. Figure 2 shows the effects of contrast adjustment. Other transforms include image sharpening and contrast enhancement. Image sharpening is performed using edge enhancement techniques such as adding a percentage of the gradient or Laplacian edge detection functions to the original grayscale image. The gradient and Laplacian have higher values at the edges of objects. In all cases, the transformed image replaces the image previously displayed. Flicker will normally transform the input imate to an output image. You can use another transform on the previously transformed image if you had set the Checkbox onSequential transforms checkbox.

2.1 Display models for image transform and brightness-contrast operations

There are several display models for combinations of using image transforms and brightness contrast or zoom filtering. These are applied to the left and right windows and also are shown in the flicker window. Two checkboxes in the upper left of the main window control transforms: Checkbox onAllow transform enables/disables transforms, and Checkbox offSequential transforms allows using the previous transform as the input to the next transform, i.e., image composition. The original image is denoted iImg. If you allow transforms and are also composing image transforms, you may optionally use the previous transformed output image (denoted oImg) as input to the next image transform. The output (either iImg or oImg) is then sent to the output1. Then the output2 which is either zoomed or not is sent to the brightness-contrast filter if active (specified by dragging the mouse in the selected window with the SHIFT-key pressed). The output2 of the brightness-contrast filter is denoted as bcImg. If you have never used the zoom or brightness-contrast filtering since loading an image, then zImg and bgImg are not generated and hence not used in the displayed image. Figure 5. illustrates these four cases.


 a) If no transforms or brightness-contrast filtering is used 
    on the selected image
                   (No transforms)
        iImg -----------------------------------> output1
  
 b) Image transforms may be composed from the original image (iImg) or
    from Sequential composition of image transforms on the
    selected image
                   (optional sequential)
                  +----------------------+
                  |                      |
                  V                      |
        iImg -----> Transform -----------> oImg --> output1 
 
  c) The image may be optionally zoomed if the magnification is not 1.0X
     on the selected image
                 (zoom)
        output1 --------> zImg ------------> output2 
     or
                 (No zoom)
        output1 ---------------------------> output2  
 
 
  d) Using brightness-contrast filter on output image
                 (BC filter)
        output2 -----------------> bcImg --> display 
     or
                 (No BC filter)
        output2 ---------------------------> display  


Figure 5. Output image as a function of image processing modes. This shows the four modes that create an output image depending on whether the brightness-contrast processing is used and if image transforms are used. The (File Reset images) menu command resets the display processors to the initial state (a).

2.2 Keyboard menu shortcut controls

There are several menu short-cut key combinations that may be used to perform operations instead of selecting the command from the pull-down menus. The command short-cut notation C-key means to hold the Control key and then press the specified key.

2.3 Sliders for defining transform parameters

The set of parameter sliders are in the upper right part of the window (Figure 1.G and Figure 6) are used for adjusting parameters for the various image transforms (see Transform menu). The size of the three image canvases may be increased/decreased using the "+" / "-" buttons under the parameter scrollbars. The current canvas size for the three image windows is displayed (in pixels).


Flicker parameter slider controls interface

Figure 6. Screen view of the Flicker parameter slider controls. This screen shot shows the parameter slider control that are used to set parameters for the various transforms. Separate parameter values are assigned to the left and right windows and are saved when you save the Flicker state. Pressing the Report scroller values button will popup the report window and display the current parameter values for both the left and right windows. The size of the three image canvases may be increased/decreased by pressing the "+" / "-" buttons under the parameter scrollbars. The current canvas size for the three is displayed (in pixels).

2.4 Example of changing image magnfication

Sometimes when comparing gels from different sources, you want want to change the magnification of one of them so they are easier to compare. Figure 7 shows an example of adjusting the magnification of the selected image by 1X, 2X and 0.5X using the zoom mag slider.

a) Image with zoom 1.0X
b) Image with zoom  2.0X
c) Image with zoom  0.5X

Figure 7 shows an example of adjusting the magnification of the selected image by 1X, 2X and 0.5X using the zoom mag slider. a) is the original image at 1.0X zoom. b) is the original image at 2.0X zoom. c) is the original image at 0.5X (de)zoom.

3. Reporting the status in the popup status window

The Flicker status information is displayed in several places.


a) Popup information windows - yes/no/cancel

b) Popup information windows - Alert

c) Popup information windows - Report


Figure 8. Screen view of the popup information windows. a) Flicker Yes/No/Cancel window to give you a chance to save data that you have edited or created. b) Flicker error or warning alert window when illegal conditions occur. c) Flicker Report window This screen shot shows the popup report window that contains a log of all activity. You can save this window's contents or clear it. If you close the window, it continues to log activity and may be popped up again using the (View | Checkbox onShow report popup) command or the Report scroller values button underneath the parameter scrollers.

4. Downloading, installing and running Flicker

The following method can be used todownload the Zipped Flicker-dist and install it as described below. This includes a launch4j windows installer.

4.1 Downloading and installing Flicker

The installation packages are now available from the Files mirror under the Flicker releases. Look for the most recent release named "Flicker-V.XX.XX-dist.zip". These include the program, required jar libraries, demo data, Windows batch and Unix shell scripts. Download the zip file and put the contents where you want to install the program. Note that there is a Flicker.exe (for Windows program). You might make a short-cut to this to use in more easily starting the program. Alternatively, you can use the sample .bat and .sh scripts to run the program explicitly via the java interpreter. Note that this method assumes that you have Java installed on your computer and that it is at least JDK (Java Development Kit) or JRE (Java Runtime Environment) version 1.5.0. If you don't have this, you can download the latest version free from the java.sun.com Website.

4.2 Downloading and installing Flicker

The following is a short procedure that is suggested for downloading and installing Flicker.
  1. In the table of contents of the home page, click on "Files mirror" under "Source Code".
  2. Under latest file releases, where it has the header "Package", click on the "open2dprot" below that.
  3. This will refresh the page and if you scroll down, it will show "Flicker files".
  4. Select the "+" on this to list the files. Pick the one with the highest version number called something like Flicker-V0.87.1.1-dist.zip
  5. Click on that to download it.
  6. Put it where you want to install it and unpack it. There is a Flicker.exe file (for Windows) as well as .bat and .sh file scripts.
  7. If you have images to compare, you can copy them or subfolders of images into the Image\ folder in the distribution directory.

4.3 Starting Flicker

There are several ways to run the program. On Windows, you can start Flicker by clicking on the startup icon shown in Figure 10 below. For Unix systems including MacOS-X, you can start Flicker from the command line by running the Flicker.jar file. If your computer is setup to execute jar files, just type the jar file. Normally it comes up with the two demonstration human plasma 2D-gel images (plasmaH.gif - an IPG gel from SWISS-2DPAGE on the left) and (plasmaL.gif - a carrier ampholyte gel from Dr. Carl Merril/NIMH on the right).

In both systems, you can specify additional command line arguments in Windows .bat and unix .sh scripts below.


REM File: Flicker-startup.bat
REM Simple Flicker batch script for Windows.
REM Starts Flicker from its jar file  on the command line.
REM To use more memory on startup, increase 96 (Mbytes) to a larger value.

java -Xmx96M -jar Flicker.jar

and

#!/bin/sh
# File: Flicker-startup.sh
# Simple Flicker batch script for Unix.
# Starts Flicker from its jar file  on the command line.
# To use more memory on startup, increase 96 (Mbytes) to a larger value.

java -Xmx96M -jar Flicker.jar


Startup Flicker icon

Figure 10. Startup icon for Flicker. This is installed on your computer (default is the desktop) when you install Flicker. Clicking on the icon starts Flicker. When you (File | SaveAs state file) to save the state of your session with the gels you have loaded, it will let you name the .flk startup file. You then can reload the state using the (File | Open state file) to restore the state.

If you have your own gels (JPEG, GIF or TIFF formats), you can try loading them. You may want to limit resolution by first decreasing their size using an image editing program like Adobe PhotoShop or the shareware program ThumbsPlus (www.cerious.org ). Large very high resolution images that are 20Mb to 40Mb will not work as well. We suggest reducing the size to about 1Kx1K for good interactivity if you have any problems with running out of memory or very sluggish response. These image editing programs can also be used for converting other formats to JPEG, GIF or TIFF formats that Flicker can read.

4.4 Requirements: minimum hardware and software requirements

A Windows PC, MacIntosh with MacOS-X, a Linux computer or a Sun Solaris computer having a display resolution of at least 1024x768. We find that a 1024x768 is adequate, but a 1280x1024 screen size much better since you can make the flicker windows larger and see the Popup Report window at the same time. At least 30 Mb of memory available for the application is required and more is desirable for comparing large images or performing transforms. If there is not enough memory, it will be unable to load the images, the transforms may crash the program or other problems may occur.

An Internet connection is required to download the program from the Flicker Web site. New versions of the program and associated demo data will become available on this Web site and can be uploaded to your computer using the various (File | Update | ...) menu commands. If you have obtained the installer software that someone else downloaded and gave to you, then you do not need the Internet connection to install the program. If you will be using the active gel image maps associated with federated 2D-gel databases, then you will need the Internet connection for accessing those databases. You do not need the Internet for local image comparisons.

Increasing or decreasing the allowable memory used by Flicker

You may increase memory by adjusting the startup .bat or .sh shell startup scripts. For very large images you could set it to 512 mb or more if your computer has at least that much memory. The allowable memory range you may set it to is 30 Mb to 1768 Mb. If you are working with very large images that require a lot of memory, you might want to increase the memory available at startup.

If you are using the Windows Flicker.exe file to start the program or clicking on the Flicker.jar file, you can't change the default startup memory.

If you are using the Flicker.jar in a script using the java interpreter as in the following example which uses the -Xmx96M (specifying using 96 at startup). Change 96 to a larger size if you want to increase startup memory.

   java -Xmx96M -jar Flicker.jar {additional command line args}

4.5 Files included in the download

The following files are packaged in the distribution and installed when you
download and install Flicker from the Web server.

4.6 Local (Flk...DB.txt) database files

When Flicker is installed, several tab-delimited (spreadheet derived with column names) .txt files are available in the DB/ directory (located where the Flicker.jar file is installed). These DB/Flk*DB.txt files are read on startup and are used to setup the (File | Open ... image | ...) menu trees.

4.7 Local Folders and files created and used by Flicker

When Flicker is first started, it will check for the following folders and files in the installation directory and create them if they can not be found.

4.8 Adding your own image data to the user Images/ database

There is another way for users to add many of their gel images without editing the DB/FlkDemoDB.txt file. When you place your image data directories in the Images/ directory, Flicker will discover them when it starts and add them to the demo menu. It works as follows:

  1. You copy or move one or more of your directories of with the images you want to use with Flicker in the Images/ folder.
  2. When Flicker starts, it creates additional submenu entries in the (File | Open user images | Pairs of images | ...) and (File | Open user images | Single images | ...) submenus that are the names of the user's directories.
  3. The first submenu contains unique combinations of pairs of all images within each of the user's directories. Selecting one of these entries will load the pair of images into the left and right Flicker image windows.
  4. The second menu command lets you select the right or left Flicker image, and then load a single image from any of the user image directories into that Flicker image window. This would be useful if you wanted to compare one of your images with one of the Internet reference gels.

4.8.1 Example of pairs of images

An example of the (File | Open user images | Pairs of images | ...) may help clarify this.
  1. Within each submenu, it will generate all unique combinations of the image files within the corresponding directory and denote them as for example, "image3 vs. image4", etc.
  2. Then just access them from the demo menu as you would with the built-in pairs of images.

For example, if you have four images image1, image2, image3 and image4 in your directory MyData-folder, then the submenu entries will be

    MyData-folderSubmenu
  • image1 vs. image2
  • image1 vs. image3
  • image1 vs. image4
  • image2 vs. image3
  • image2 vs. image4
  • image3 vs. image4

Note that it does not generate comparisons between directories. You can still do that by clicking on the left (and then later the right) image and using the (File | Open image file) command to manually load the file into the image. If you want to do this often, put your images in the same directory.

If you have this type of data, it will also add the (File | Open user images | List user's images by directory) command. You can use this to get a report of all of the files in the popup report window.

4.9 Updating the latest versions of the program and data from the Web server

You can update your program and active image map and demo image data files using the various Update options in the Files menu. The (File | Update | Flicker program) command downloads and installs the latest Flicker.jar file. The (File | Update | Active Web Maps DB) command downloads and installs the latest active Web maps database DB/FlkMapDB.txt file. The active maps point to federated 2D-gel web servers with identified spots. The (File | Update | Demo images DB) command downloads the latest demo images and the DB/FlkDemoDB.txt file.

4.9.1 Instructions for using an older version of Flicker

The version of flicker you use is dependent on the version of the Flicker.jar file.

You will not use the (Files | Update | Flicker program) command. Using this command will get the latest release which is not what you want if you want an earlier release.

Instead do the following. You copy the version of Flicker.jar you want to the location on your disk where you had installed Flicker overwriting the previous version. For example, on MS Windows this is typically

 
    C:\Program Files\Flicker\Flicker.jar
If you installed Flicker elsewhere on your computer, then that is where you need to change it. Go to the files distribution in the
File mirror web page.

There are a number of .jar files of the form

   Flicker.jar-V0.xx
Copy the one you want to your computer.

To be used with the Flicker startup process, this file must be called Flicker.jar, so you must rename it as Flicker.jar. The procedure is as follows:

  1. copy Flicker.jar-V0.xx to your computer (where V0.xx is the version number),
  2. rename the file to "Flicker.jar"
  3. copy it to C:\Program Files\Flicker\Flicker.jar or to where it was installed on your computer,
  4. then start (or restart) Flicker. It will then get the new version of the Flicker.jar file you changed.

4.9.2 Adding your own or another Web sites demo data to your Flicker Demo database

You can add set set of demo gel data to the Flicker demo database from any Flicker demo-data compatible web site. This data must be is exactly the form required that is spelled out in this manual (see Section 4.3 details on FlkDemoDB file formats. Once you have confirmed that the Web site is compatible, it is simple to add that data to your local Demo database. If the Web site data changes, when you do the update, it will replace existing entries with the new data from that Web site. NOTE: all file names are case-dependent so becareful when building your DB/ tables and in naming the images. The Web site should have 2 folders:

   DB/
and
   Images/
The DB/ folder must have two files FlkDemoDB.dir (the list image images in the Images/ folder, and FlkDemoDB.txt which is a tab-delimited spread sheet describing the demo images. NOTE: demo images generally live in the top level of the Images/ directory. They are not in subdirectories of the Images/ directory. If you are designing such a remote demo Web site, you could model the files from the current Flicker DB files.

Once you are sure your remote web site is set up correctly, then simply use the (File | Update | Add user's Flicker Demo Images DB by URL) command to download and and update the Flicker demo database. After it is successful, it will tell you to exit and restart Flicker. If you go to the Files | Open demo images| ... menu, you should see the new demo data you have installed.

5. Saving and restoring the Flicker state

Flicker gives you the option of saving the current state of your session including the images your are looking at and the parameter values of the sliders, etc. To save the current state, use the (File | Save (or SaveAs) state file) command. This creates a file with a .flk file extension in the installation FlkStartups/ folder (default DB/FlkStartup.flk). Any time while running Flicker, you can also use (File | Open state file) command to change it to another saved Flicker state.

The Flicker.properties file is the user-specific preferences for generic properties such as colors, view options, etc. This file is created when you exit flicker and read (if it exists) when you start it. If you have never run flicker or the file was deleted, Flicker uses the default values. If the Flicker.properties file exists, it overides these files. If you have started Flicker using a .flk startup file, this in turn overides any settings from the Flicker.properties file. For example, you may want to use a red trial object cursor instead of yellow, etc. If you have both a Flicker.properties file and are starting Flicker using a .flk startup file, it (1) reads the user preferences first from Flicker.properties, and then (2) reads the .flk startup file to overide these preferences. If you want to reset the standard view, use the (Edit | Reset default view) command to overide the previous view read from Flicker.properties. If the you ever have problems starting Flicker because of a corrupted Flicker.properties file, just delete it (it is kept in the same directory where you installed Flicker) and restart Flicker. When you exit, it will create a new properties file.

6. Pull-down menus

The menu bar commands are divided into menus divided by function.
  1. File menu - to load/save the Flicker .flk state, load images, active map urls, update (from the server) program, DB/Flk*DB.txt database files, demo images
  2. Edit menu - to change various defaults
  3. View menu - to change the display overlay options
  4. Landmark menu - to define landmarks for warping or other operations
  5. Transform menu - contains various image processing transforms
  6. Quantify menu - contains circle and boundary measurements, ROI, gray to OD calibrations
  7. Help menu - popup Web browser documentation on Flicker

Menu notation

In the following menus, selections that are sub-menus are indicated by a 'Indicates that the
menu has a submenu'. Selections prefaced with a 'Checkbox on' and indicate 'Checkbox off' indicate that the command is a checkbox that is enabled and disabled respectively. Selections prefaced with a 'Radio button on' and indicate 'Radio button off' indicate that the command is a multiple choice "radio button" that is enabled and disabled respectively, and that only one member of the group is allowed to be on at a time. The default values set for an initial database are shown in the menus. Selections that are not currently available will be grayed out in the menus of the running program. The command short-cut notation C-key means to hold the Control key and then press the specified key.

6.1 File menu

These commands are used to load/save the Flicker .flk state, load images, active map URLs, update (from the server) program, DB/Flk*DB.txt database files, demo images, and user's images. It also saves and restores the Flicker state, does updates from the server. You can save transformed or overlay images as GIF files in the tmp/ directory.

6.2 Edit menu

These commands are used to change various defaults. These are saved when you save the state and when you exit the program.

6.3 View menu

These checkbox menu commands are used to change the display overlay options. Some options (e.g., view Landmarks, view ROI, etc.) will not display any overlays until you define the corresponding data. The Flicker images (C-F) checkbox menu command can also be accessed from the Flicker checkbox in the upper left corner of the window.

6.4 Landmark menu

These commands are used to define landmarks for image warping or other operations. First select the image, then click on the position you want to use as a landmark, then do Add landmark (C-A).

6.5 Transform menu

These commands are used contains various image processing transforms. First select the image you want to transform. For some transforms, if you don't select either image it will do the transform on both images. Then select the transform from the Transform menu.

6.5.1 Example affine warping an image to the geometry of the other image

This example warps the right image to the geometry of the left image to make them easier to flicker compare. There are two warping transforms - affine that requires 3 landmarks. You first define the required 3 pairs of corresponding landmarks between the triangular region you are interested in warping (see the landmark vignette and the using warping vignette for more info). Then select the gel you wish to warp. You then apply the warp transform from the Transform menu. We illustrate this with the two triangle test images testA and testB. Flicker has predefined landmarks for the plasmaH/plasmaH and testA/testB demo images that you can easily invoke for this example (see step [2]).

  1. Load the test images using (File menu | Open demo images | Test images | Affine warp test A and B) command. The images are shown in Figure 11a.
  2. Define the landmarks. You can do this using the Landmark commands or use a demo short cut (Landmark menu | Set 3 pre-defined landmarks for demo images (C-Y)) command. The images are shown in Figure 11b.
  3. Set Checkbox onAllow transforms checkbox enabled.
  4. Set Checkbox offSequential transforms checkbox disabled.
  5. Select the right image window you want to warp.
  6. Perform the transform you want to try in the (Transform | Affine warp) or (Transform | Poly warp) command.
  7. Reposition the transformed image and the other image to the spot of interest inside of the landmark region. The recentered warped images are shown in Figure 11c.
  8. Enable flickering. It should then be easier to see the cooresponding spots.

a) Affine original test images A and B
b) Affine landmarked test images A and B
c) Affine warped test images A and B

Figure 11. Example using the affine transform. a) shows the original left and right images. b) shows the left and right images with 3 pairs of landmarks after they are added (large red A, B and C labels). c) shows the two images after applying the affine transform to the right image and recentering it.

6.6 Quantify menu

These commands are used to define and measure integrated density (grayscale or calibrated OD if calibrated) for circle, boundary, region-of-interest (ROI) measurements. Integrated density measurements are made on the 8-bit (0:255 gray-value) data of pixels. It is only valid on grayscale data since we do the measurements on the least significant 8-bits (blue channel of the 24-bit RGB data). If you have color data, you can use the NTSC color to gray-scale transform to convert it to gray scale first. If you have calibrated grayscale to optical density (OD), you get the measurement in terms of OD rather than grayscale. The calibration wizard also lets you define the calibration in terms of other unitsy.

In the mean time, we refer to "density" as either of these two measurements. You may measure the total integrated density (summing the pixel gray values or OD), or mean density (the total density/#pixels in the region). This background density is used to correct the measurement density if it was defined (otherwise 0.0 is assumed). Note that you may clear the background measurement circle using the (C-W) command.

Creating lists of spots

Flicker was not designed to measure very large numbers of spots. That said, it could be used that way but with a lot of manual work. We provide some commands to make it easier to quantify (C-B) and (C-M) or (ALT-click), annotate (C-I), edit (C-E), and delete (C-K). You can also list and save the measured spot lists for the two images. The measured spot lists automatically get saved if you save the .flk startup state (File | SaveAs state file). Opening Flicker using that startup state file will restore the measured spot list.

You can save the spot list in a tab-delimited file suitable for import to Excel, by 1) clearing the Popup Report Window; 2) select the image you want and use (Quantify | Measure by circle | List spots in the spot list (tab-delimited)) command; 3) then, Save the text in the Popup Report Window or cut and paste it into Excel, etc.

It is possible to generate a list of paired spots between the two images using the (Quantify | Measure by Circle | List paired 'id' annotated-spots in both spot lists (tab-delimited)) command. It lists paired spots that occur in the spot lists of both gels and have the same annotation 'id' values (case-sensitive). The user assigns the spot 'id' annotations using the (C-I) spot editing command to assign the case-sensitive spot identifiers. (C-E) command may also be used to edit the ids'. The paired spot data list may be exported to Excel similar to what was described in the last paragraph for spot lists.

Note that the background density is not the same everywhere on the gel image. Therefore if you are measuring spots in regions of the gel with quite different background (e.g., tail streaks from other spots, etc.), to get better estimated quantification you need to redefine the background adjacent to where you are making measurements. Recent versions of Flicker track the most recent background (C-B) estimate and associate it with new measured spots (C-M) until you redefine it.

Figures 12a-12h show various permuations of the spot list overlay options. Figure 13 shows an example of a histogram of the Region Of Interest (ROI). Figure 14 shows examples of calibrating gray scale a step wedge scanned with the image using the step wedge calibration wizard. Figure 15 shows calibrating grayscale where there are calibration spots in the image by using the spot list calibration wizard.

6.6.1 Spot measurements

Figures 12a-12h show various permuations of the viewing spot quantification using the various spot list overlay options.

a.1) panel a.1 - single spot image a.2 panel a.2 - single spot report
b.1) panel b.1 - image measured spot list 3 spots b.2) panel b.2 - report measured spot list 3 spots
c) panel c.1 - measured spot list with '+' d) panel c.1 - measured spot list with 'circle'
e) panel d.1 - image annotated 3 measured spots f) panel d.2 - report annotated 3 measured spots
g) panel e.1 - image annotated 3 measured spots h) panel e.2 - report annotated 3 measured spots

Figure 12. Examples of the measured spotlist. This figures show various options in displaying the measured spots. As a shorthand for this legend, VM: is the (View | Set view measurements options | ...) submenu.

Panels (a.1) and (a.2) show a single spot measurement image and report and does not create a list of measured spots. The (Quantify | Checkbox onList-of-spots else trial-spot measurement-mode (C-J)) should be turned off. The VM: Checkbox offView measurement circle option should be enabled.


Panels (b.1) and (b.2) show a measured spot list with three spots, image and report respectively. Spots are shown with circles and spot number annotation. Since the user had clicked on the third spot, it is considered the "current" spot in the spot list and is indicated in yellow. The rest are indicated in red. The (Quantify | Checkbox onList-of-spots else trial-spot measurement-mode (C-J)) should be turned on. The VM: Checkbox offUse 'circle' for measured spot locations option should be turned on, VM: Checkbox offUse 'spot number, for spot annotations option should be turned on.
Panel (c) shows the measured spot list with a "+" instead of a circle with spot numbers. Since the user had clicked on a different part of the screen, there is no "current" spot in the spot list so all spots are shown in red. The (Quantify | Checkbox offList-of-spots else trial-spot measurement-mode (C-J)) should be turned on. The VM: Checkbox offUse '+ for measured spot locations option should be turned on, VM: Checkbox offUse 'spot number, for spot annotations option should be turned on.
Panel (d) show a measured spot list with three spot measurements image and report. Spots are shown with circles, spot numbers and spot annotation. The (Quantify | Checkbox onList-of-spots else trial-spot measurement-mode (C-J)) should be turned on. The VM: Checkbox onUse 'circle' for measured spot locations option should be turned on, VM: Checkbox onUse 'spot number, for spot annotations option should be turned on, and VM: Checkbox onUse 'spot identifier, for spot annotations option should be turned on. The user had edited the spot identifiers by (1) clicking on a spot, (2) doing the (Quantify | Measure by circle | Edit selected spot from spot list (C-E)) command, and 3) typing a spot "identifier" for that spot and pressing "Done". Spots where the 'id was not edited are indicated by "<none>". For this example, we set 'id' to "SpotOfInterest" for spot #1 and a space for spot #3. Spaces make the identifier disappear.
Panel (e) show a measured spot list with three spot measurements image and report. Spots are shown with pluses, spot numbers and spot annotation. The (Quantify | Checkbox onList-of-spots else trial-spot measurement-mode (C-J)) should be turned on. The VM: Checkbox onUse '+' for measured spot locations option should be turned on, VM: Use 'spot number, for spot annotations option should be turned on, and VM: Checkbox onUse 'spot identifier, for spot annotations option should be turned on.
Panel (f) show a measured spot list with three spot measurements image and report. Spots are shown with circles and spot annotation. The (Quantify | Checkbox onList-of-spots else trial-spot measurement-mode (C-J)) should be turned on. The VM: Checkbox onUse 'circle' for measured spot locations option should be turned on, and VM: Checkbox onUse 'spot identifier, for spot annotations option should be turned on.
Panel (g) show a measured spot list with three spot measurements image and report. Spots are shown with pluses and spot annotation. The (Quantify | Checkbox onList-of-spots else trial-spot measurement-mode (C-J)) should be turned on. The VM: Checkbox onUse '+' for measured spot locations option should be turned on, and VM: Checkbox onUse 'spot identifier, for spot annotations option should be turned on.
Panel (h) show a measured spot list with three spot measurements image and report. Spots are shown with just spot annotation. The (Quantify | Checkbox onList-of-spots else trial-spot measurement-mode (C-J)) checkbox option should be turned on. The VM: Checkbox onUse 'spot identifier, for spot annotations option should be turned on.

6.6.2 Region of Interest histogram display

You can compute a histogram of the current region of interest in the selected image. Figure 13 shows an example of a histogram of the Region Of Interest (ROI).

Example grayscale histogram of ROI of image

Figure 13. Example of a grayscale histogram of a region in the image. This popup window shows the grayscale histogram under the computing window region of interest (ROI). If no ROI was defined (the case shown here), it computes the histogram over the entire image. It is invoked by (Quantify | Region Of Interest (ROI) | Show RPI grayscale histogram (C-H)). Clicking on a value of the histogram will show the frequency of the specified gray value at the top of the display.

6.6.3 The ND step wedge grayscale calibration [ALPHA-level code]

It is useful and sometimes essential to calibrate an image using known standard density values. If the gel stain is stoichiometric within limits, density corresponds to protein concentration. Then within the contraints of linearity of the staining, range and saturation of the scanner, it is possible to get more accurate spot density measurements. One way to do do this is to scan the gel (or image) with a neutral density step wedge (Suppliers: such as Stauffer Graphic Arts or similar) with known optical density (OD) values for each step. Note that if you have step wedges calibrated in other units (e.g., counts-per-minute or CPM, then you can specify that to the calibration wizard). If the gray values are mapped to the corresponding optical density values, the wizard interpolates the intervening values constructing a translation table to map gray scale (in the range of [0:255] used in Flicker) to the coresponding OD or other calibration values. Then when measurements are made using the Quantify menu commands (circle mask or ROI), the data is first mapped to the calibrated units rather than grayscale. The sum of the pixel gray values is computed using this map so the measurement is the sum of the optical densities or integrated density/spot measurement area. This gives a better estimate of the protein concentration.

Once an image is calibrated and the calibration saved (in the {installation directory}/cal/{imageFile}.cal file), it may be reused everytime the image is loaded into Flicker. The initial calibration is created from the step wedge data and known corresponding OD values using a histogram specified by a region of interest (ROI) specified as the step wedge region.

To make it easier to demonstrate this process, we have set up special demo calibration data for the four demo Leukemia gels. If you have enabled (Quantify | Calibration | Use demo leukemia gels ND wedge calibration preloads) checkbox, it will preload the OD values and step-wedge ROI for demonstration purposes. If you are using any other data, you must specify the OD values and step-wedge ROI. You invoke the wizard by the (Quantify | Calibration | Optical density by step wedge) command. This will popup the calibration wizard window.

Procedure: for calibrating the ND step wedge

  1. If you are using the preloaded demo leukemia gels data specified above, then this step is done for you automatically. Setup a well-define ROI region around the ND step wedge in the image using (C-U) upper left-hand corner and (C-L) lower right-hand corner. Then press the Analyze wedge ROI button in the wizard. This computes the histogram of the step wedge region and attempts to find the peaks in the histogram corresponding to the mean wedge values. It will then put them in the peak table on the right of the wizard.

  2. If there are no OD data in the peaks table, then enter the OD calibration values into the red Optical-Density fields. [If the calibration was set previously and we read them in from the .cal file, then these files are preset as well as the corresponding grayscale Gray-peak field values if you know what the values are. Press the Update peak table button in the wizard to recompute the OD calibration and update the calibration plot. Note: If the current gel is not calibrated and the other gel has a calibration step list of OD values, then it will use it to save you having to type it in.

  3. To force it to analyze the ROI wedge area, click on the Analyze wedge ROI button. This recomputes the histogram on the ROI (which may have changed) and the recomputes the calibration curve.

  4. This will also update the Calibration Peak Table and generate the extrapolated gray to OD translation map calibration. The new histogram will show the Gray-peak values cooresponding to the OD values with red tick marks on the peaks as follows:
    4.1 It tries to find the peaks and copies the peaks into the Calibration Peak Table Gray-peak fields.
    4.2 It then generates a piecewise-linear extrapolation of the peak-table data to generate the translation map.
    4.3 It then redraws the histogram plot with a) overlay calibration curve which is the gray to OD map, b) updates the peaks table of (OD values, peak gray values) and draws this data into the plot.

  5. You may edit the peak list, by selecting a peak with the mouse and then pressing either Add peak or Delete peak button in which case it redoes the step 4.

  6. When you are done editing you may save the calibration by pressing the Save calibration state button. This saves the calibration data in the cal/{imageFile}.cal and makes the gray to OD calibration available to the image. You can then make measurements calibrated in OD.

  7. Press Done to exit the calibration wizard. If you have not saved the calibration and do not want to, it will prompt you to save it and you should press the No button.

a) Calibrating ND wedge ROI image
b) Calibrating ND wedge table before edit
c) Calibrating ND wedge table after edit

Figure 14. Example of calibrating grayscale using the step wedge calibration wizard. This shows an example of calibrating the gray scale using a ND step wedge that was scanned with the image. The OD values corresponding to the steps are known and are entered into the peak table. a) The ROI region over the ND step wedge was defined. In this example using one of the demo leukemia gels (AML), we used the preload option (Quantify | Calibration | Use demo leukemia gels ND wedge calibration preloads) command. Then, startup the wizard by using the (Quantify | Calibration | Optical density by step wedge) command. If you did not do this, then you must define the ROI for the wedge region yourself and then press the Analyze wedge ROI button. b) Shows the calibration wizard window with the histogram on the left, the peak table on the right and control buttons on the bottom. This is before editing the histogram. If you were defining the calibration values from scratch, enter them in the peak table and define the calibration units and units abbreviation. Then press the Update peak table button. c) Because there are some bad peaks (#7, grayscale of 143) and some that were missed (grayscale peaks at 214 and 220), we need to edit the peak table. Click on each peak in the histogram you want to delete and then press the Delete peak button. To add peaks, click on each peak in the histogram you want to add and then press the Add peak button. When you are satisfied with the calibration, press the Save calibration file to save the calibration in the {installation directory}/cal/{imageName}.cal file and then press Close to exit the wizard. A good calibration should be a smooth continuous function with no kinks. If you forgot to save the calibration when you leave the wizard, it will ask you if you want to save it. If you don't, it will revert to the previous calibration if any.

6.6.4 The Spot list grayscale calibration [ALPHA-level code]

There is an alternative calibration method. You can calibrate grayscale if have a set of calibrated spots or regions in the image instead of a calibration step-wedge. You do not use the ROI, but instead will specify a set of spot measurements of increasing darker regions that correspond to your calibration values (such as OD, CPM, etc). (Quantify | Calibration | Optical density by spot list) command. This will popup the calibration wizard window.

a) Calibrating grayscale using spot lists
b) Calibrating grayscale using spot lists - table before edit

Figure 15. Example of calibrating grayscale using the spot list calibration wizard. This shows an example of calibrating the gray scale using a set of known calibrated regions or spots that were scanned with the image. The OD or other calibration values corresponding to the spots are known and are entered into the peak table. a) We selected a set of spots over the ND step wedge but any set of known regions could be used. In this example using one of the demo leukemia gels (AML), we used the preload option (Quantify | Calibration | Use demo leukemia gels ND wedge calibration preloads) command. Then, startup the wizard by using the (Quantify | Calibration | Optical density by spot list) command. If you did not do this, then you must define the OD list of calibration values yourself and then press the Update peak table button. b) Shows the calibration wizard window with the histogram on the left, the peak table on the right and control buttons on the bottom. If you are defining the calibration values from scratch, enter the OD (or other calibration values) into the peak table and define the calibration units and units abbreviation. Then press the Update peak table button. You may edit the peak tale (just as you can for the ND wedge calibration). When you are satisfied with the calibration, press the Save calibration file to save the calibration in the {installation directory}/cal/{imageName}.cal file and then press Close to exit the wizard. A good calibration should be a smooth continuous function with no kinks. If you forgot to save the calibration when you leave the wizard, it will ask you if you want to save it. If you don't, it will revert to the previous calibration if any.

6.6.5 Example of measuring multiple spots using the circular mask

This gives an example of how do you can measure spot intensity under the circular mask. First, the background corrected measurement estimate is computed under the circular mask (C-M). This background estimate is then used for multiple measurements until you change this background estimate. The current background intensity measurement is associated with all spots measured since it was defined or redefined and is saved in the spot list. You number the spots by enabling the (View menu | Set view measurement options | Checkbox onView measurement circle) option. The numbered image is shown in Figure 16a.

You may also list the saved spots in the report window (shown in Figure 16b). Hint, press the Clear button in the report window first. Note that if you save the flicker state, then the spot lists will be saved in the .flk file state and associated .spt spot list files in the spt/ directory. Flicker will restore the spot lists if you start flicker on the saved .flk startup file.

  1. Enable the multiple spot list measurements using the (Quantify | Checkbox onList-of-spots else trial-spot measurement-mode (C-J)) menu checkbox.
  2. Set the measurement circle size for the size spots you want to measure using the meas circle diameter scroller. This sets the box around the circle as NxN to 1x1, 3x3, 5x5, ..., or 51x51.
  3. Select the (Quantify | Measure by circle | Capture background (C-B)) or type (C-B) to capture the background value
  4. Select the (Quantify | Measure by circle | Capture measurement (C-M)) or type (C-M) to capture the spot measurement value. You may use (ALT-key click) to both select the spot and add it to the measurement list in one operation.
  5. To delete a spot, click on the spot. Then use the (Quantify | Measure by circle | Delete selected spot from spot list(C-K)) command. The next spot you measure will get the next spot measurement number - it does not reuse measurement numbers.
  6. To edit a spot's annotation 'id' data, click on the spot. Then use the (Quantify | Measure by circle | Edit selected spot(s) 'id' field from spot list(s) (C-I)). If spots are selected in both images, then you can edit both spots together.
  7. To edit all of a spot's data, click on the spot. Then use the (Quantify | Measure by circle | Edit selected spot(s) from spot list(s) (C-E)). If spots are selected in both images, then you can edit both spots together.
  8. Repeatedly measure the spots you want using steps [2-7] as required.
  9. See the discussion on the various spot overlay options.
  10. You can review the list by first clearing the popup report window and then doing a (Quantify | Measure by circle | List spots in the spot list). You can also view the list as tab-delimited data that you can then either cut and paste into Excel.

a)Image showing measuring multiple spots
b)Report for measuring multiple spots

Figure 16. Example of measuring multiple spots. a) shows the left image window with 4 spots measured. The background spot has a magenta circle and "+B". The 4 spots are numbered "+1", "+2", to "+4". The current cursor position is shown with the red circle with an orange "+" inside of it and the total gray value shown in the image title is the data under the circular mask at this position. b) shows the popup report window with the 4 spot measurements. We "Clear"ed the report to before posting the data to have it contain just the spot data.

6.6.6 Examples of annotating spot 'ID's in the spot lists

Flicker allows you to annotate spots in the spot list and to then generate paired-spot tables (tab-delimited) that you can export (to Excel etc.). Figure 17 shows 3 spots that were putatively identified by flickering the right gel against the Swiss-2DPAGE database image and then clicking on each of the corresponding spots to bring up the putative identifications (see Figure 2). Once the paired spot identifications are assigned,

a)Assigning ID labels for spots previously identified
b)Assigned ID labels prompt
c)Assigned spot ID labels edit prompt

Figure 17. Example of assigning spot annotation 'id's. a) shows the labeled spot annotations for three spots previously putatively identified (not shown here) using flickering against the SWISS-2DPAGE clickable database (see
Figure 2). The spots were added to the spot lists in each of the two gels using the (Quantify | Measure by circle | Capture measurement (C-M)) command on each spot. Then, b) shows the prompt for assigning the paired-spot identifier that is popped up by first selecting the corresponding measured spots in each gel (shown in yellow) and then using the (Quantify | Measure by circle | Edit selected spot(s) 'id' field from spot list(s) (C-I)) command. An alternate editing method, c) shows the prompt for editing all fields of the paired-spots that is popped up by first selecting the corresponding measured spots in each gel (shown in yellow) and then using the (Quantify | Measure by circle | Edit selected spot(s) from spot list(s) (C-E)) command.


Flicker can then use the annotated spot lists you have generated to create a paired spot table shown below.

a.1)Paired spot lists
a.2)Paired spot lists
b.1)Report of paired spot list data
b.2)Report of paired spot list data

Figure 18. Example of paired spot lists exported to Excel. a.1-a.2) shows data exported to Excel from the above example (
Figure 17). The annotated (ids') spot lists were generated by clicking (for each gel) on the image then using the (Quantify | Measure by circle | List spots in the spot list (tab-delimited)) command to generate a tab-delimited spot this. This was then cut and pasted into Excel and then reorganized to better show the data for this Web page. Then, b.1-b.2) shows the paired spot table generated using the (Quantify | Measure by circle | List 'id'-paired annotated mean norm. spots in both spot lists (tab-delimited)) command. The table was then cut and pasted into Excel and then reorganized to better show the data for this Web page.

6.6.7 Examples of typical print-data windows

A spot was first selected by clicking on it. The print window size was set to 20x20 and the data radix to Decimal for grayscale values. Then the following output was generated in the popup Report window using the (Quantify menu | Print data-window | Show data-window of selected pixel (C-V)) command. Normally, first set the print-window size and data radix then use the (C-V) short-cut key after you have selected the spot you want to view. The following shows typical output for an uncalibrated image where you can see tow spots in the lower left quadrant:


Windmp [183:203, 168:188] Center (193,178) 20X20 size,
sampled: 1 pixels, data-radix: Decimal
Image: Images\plasmaH.gif
    X 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203
  Y   --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---
 168   71  61  57  55  54  54  56  57  56  50  46  42  42  43  45  42  43  48  53  67  80
 169   71  53  50  48  45  48  50  55  60  56  46  42  40  43  42  40  37  41  47  54  65
 170   88  49  44  42  40  42  45  53  56  61  50  41  40  39  39  37  34  37  38  45  54
 171   97  49  41  39  39  40  43  53  60  61  54  43  39  38  37  36  34  36  37  43  50
 172  106  47  39  37  36  37  39  53  72  78  72  50  43  38  37  35  33  34  35  39  44
 173   84  41  38  37  34  33  35  50  82  94  84  58  48  41  40  37  34  35  35  39  44
 174   66  39  38  37  35  33  35  50  84  96  84  59  48  41  40  39  35  37  37  39  44
 175   47  41  43  40  36  34  34  49  78  84  71  56  50  43  44  43  38  37  37  47  46
 176   50  46  46  46  39  34  35  56  91  95  77  61  58  54  57  54  47  43  41  43  47
 177   53  49  51  50  42  37  38  69 117 122  98  74  66  62  65  62  51  47  44  45  50
 178   58  59  65  65  53  43  46 106 171 174 139  94  78  71  67  65  57  54  50  48  54
 179   63  77  97  97  82  59  55 104 163 164 120  76  64  58  62  62  61  58  55  52  56
 180   67  90 122 124 106  72  60  86 132 132  95  64  59  55  64  62  61  59  57  53  57
 181   76 140 189 193 174 128  94  59  70  68  60  55  55  54  59  63  60  60  58  55  58
 182   82 167 214 215 195 137  97  50  47  49  52  53  53  53  53  56  55  57  59  57  61
 183   73 142 194 194 160  97  67  42  44  46  51  52  52  50  53  52  54  57  60  62  63
 184   51  62  81  80  60  46  39  38  44  46  51  52  52  51  54  54  66  69  78  80  77
 185   48  50  52  52  46  40  39  40  45  48  51  52  51  53  56  57  56  65  70  72  72
 186   49  49  50  50  46  41  40  40  42  46  49  51  51  53  55  56  53  62  60  61  61
 187   51  55  63  62  56  46  43  40  40  41  45  51  53  57  58  55  50  48  52  49  50
 188   70  90  97  90  71  57  52  47  41  40  46  56  61  66  64  60  51  46  48  47  50

Example of a print-data window from an OD calibrated gel

If you have a calibrated image (see (Quantify menu | Calibrate | ...), then you can view the calibrated pixels in an OD radix. The following AML demo leukemia gel was calibrated in optical density. The spot was first selected by clicking on it. The print window size was set to 20x20 and the data radix to Optical-density for od values. Then the following output was generated in the popup Report window using the (Quantify menu | Print data-window | Show data-window of selected pixel (C-V)) command. Normally, first set the print-window size and data radix then use the (C-V) short-cut key after you have selected the spot you want to view. The following shows typical output for an uncalibrated image:


Windmp [183:197, 322:336] Center (190,329) 15X15 size,
sampled: 1 pixels, data-radix: Optical-density
Image: Images\HUMAN-AML.ppx
    X   183   184   185   186   187   188   189   190   191   192   193   194   195   196   197
  Y   ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- -----
 322  0.022 0.022 0.027 0.033 0.038 0.056 0.066 0.072 0.084 0.056 0.049 0.047 0.033 0.040 0.047
 323  0.018 0.022 0.020 0.042 0.058 0.058 0.097 0.139 0.090 0.066 0.053 0.029 0.027 0.029 0.036
 324  0.020 0.013 0.024 0.040 0.049 0.051 0.127 0.133 0.072 0.060 0.058 0.038 0.036 0.042 0.033
 325  0.018 0.027 0.038 0.038 0.078 0.127 0.151 0.157 0.145 0.072 0.049 0.040 0.042 0.033 0.038
 326  0.024 0.022 0.033 0.066 0.139 0.188 0.291 0.304 0.265 0.115 0.056 0.040 0.038 0.031 0.033
 327  0.018 0.029 0.047 0.109 0.265 0.401 0.534 0.495 0.337 0.194 0.078 0.031 0.029 0.036 0.029
 328  0.038 0.029 0.058 0.182 0.394 0.665 0.766 0.648 0.466 0.252 0.097 0.058 0.033 0.022 0.022
 329  0.027 0.031 0.066 0.239 0.495 0.724 0.816 0.674 0.522 0.272 0.121 0.051 0.027 0.024 0.024
 330  0.036 0.044 0.127 0.220 0.394 0.557 0.622 0.557 0.372 0.246 0.139 0.040 0.033 0.038 0.027
 331  0.027 0.036 0.060 0.145 0.291 0.394 0.394 0.357 0.291 0.176 0.066 0.038 0.031 0.029 0.031
 332  0.024 0.033 0.044 0.090 0.133 0.233 0.285 0.246 0.207 0.151 0.090 0.058 0.056 0.042 0.049
 333  0.027 0.018 0.042 0.060 0.115 0.170 0.239 0.239 0.246 0.182 0.157 0.188 0.145 0.145 0.182
 334  0.018 0.031 0.044 0.051 0.097 0.157 0.252 0.304 0.272 0.291 0.246 0.233 0.291 0.317 0.365
 335  0.033 0.031 0.042 0.058 0.151 0.176 0.259 0.311 0.343 0.343 0.324 0.298 0.291 0.350 0.430
 336  0.018 0.036 0.056 0.090 0.139 0.252 0.291 0.304 0.357 0.298 0.265 0.246 0.272 0.265 0.317

6.7 Help menu

These commands are used to invoke popup Web browser documentation on Flicker. The documentation is kept on the Internet at http://open2dprot.sourceforge.net/Flicker. Normally, these help commands should pop up a Web browser that directly points to the Web page on the http://open2dprot.sourceforge.net/Flicker site. If your browser is not configured correctly, it may not be able to be launched directly from the Flicker program. Instead, just go to the Web site with your Web browser and look up the information there.

7. Demonstrations

The Flicker program integrates these various procedures to help you try to make putative spot identifications. See the Quick start examples on the home page for a short list of some of these methods.

As part of the demonstrations, we present a series of as short vignettes that have answers to specific "How do I do ...?" types of questions. There are several demonstration images that are available when you download and install Flicker. Look in the (File | Open demo images) menu. These commands will load pairs of demonstration images.


8. Flicker References

  1. Lemkin PF, Thornwall G, Evans J (2005) Comparing 2-D Electrophoretic Gels Across Internet Databases. John Walker (ed), The Protein Protocols Handbook, Humana Press Inc, Totowa, NJ, pp 279-305. [describing the application version]

  2. Lemkin PF, Thornwall G (2002) Flicker image comparison of 2-D gel images over the Internet. John Walker (ed), The Protein Protocols Handbook, pp 197-214. [describing the applet version]
  3. Lemkin PF, Thornwall G (1999) Flicker image comparison of 2-D gel images for putative protein identification using the 2DWG meta-database. Molecular Biotechnology 12(2) 159-172. [describing the applet version]
  4. Lemkin PF (1997c) 2DWG meta-database of 2D electrophoretic gel images on the Internet. Electrophoresis, 18, 2759-2773. [Extended paper, describing the applet version]. The 2DWG server
  5. Lemkin PF (1997b) Comparing 2D Electrophoretic gels across Internet databases. In 2-D Protocols for Proteome Analysis, Andrew Link (Ed), a book in Methods in Molecular Biology, Vol. 112, Humana Press, Totowa, NJ, pp 339-410. [describing the applet version]
  6. Lemkin PF (1997a) Comparing Two-Dimensional electrophoretic gels across the Internet. Electrophoresis, 18, 461-470. [Extended paper, describing the applet version]. The flicker applet server


8.1 Additional Proteomics References

[1] Herbert B.R., Pederson S.L., Harry J.L., Sebastian L., Traini M.D., McCarthy J.T., Wilkins M.R., Gooley A., Packer N.H., Williams K. (2003) Mastering genome complexity using two-dimensional gel electrophoresis. PharmaGenomics Sept, 22-36.

[2] Hood L. (2002) A Personal View of Molecular Technology and How It Has Changed Biology. J Proteome Biology 1, 399-409.

[3] Herbert B.R., Pedersen S.K., Harry J.L., Sebastian L., Grinyer J., Traini M.D., McCarthy J.T., Wilkins M.R., Gooley A.A., Righetti P.G., Packer N.H., Williams K.K. (2003) Mastering Proteome Complexity Using Two-Dimensional Gel Electrophoresis. PharmaGenomics 3, 21-36.

[4] Pedersen S.K., Harry J.L., Sebastian L., Baker J., Traini M.D., McCarthy J.T., Manoharan A., Wilkins M.R., Gooley A.A., Righetti P.G., Packer N.H., Williams K.L., Herbert B.R. (2003) Unseen Proteome: Mining Below the Tip of the Iceberg To Find Low Abundance and Membrane Proteins. J Proteome Biology 2, 303-311.

[5] Pieper R., Su Q., Gatlin C.L., Huang S.-T., Anderson N.L., Steiner S. (2003) Multi-component immunoaffinity subtraction chromatography: An innovative step towards a comprehensive survey of the human plasma proteome. Proteomics 3, 422-432.

[6] Pieper R., Gatlin C.L., Makusky A.J., Russo P.S., Miller S.S., Su Q., McGrath A.M., Estock M.A., Parmar P.P., Zhao M., Huang S.-T., Zhou J., Wang F., Esquer-Blasco R., Anderson N.L., Taylor J., Steiner S. (2003) The human serum proteome: Display of nearly 3700 chromatographically separated protein spots on two-dimensional electrophoresis gels and identification of 325 distinct proteins. Proteomics 3, 1345-1364.

[7] Anderson N.L., Anderson N.G. (2002). J Mol. Cellular Proteomics 1, 845-867; and J Mol. Cellular Proteomics 2, 50.

[8] Liotta L.A., Espina V., Mehta A.I., Calvert V., Rosenblatt K., Geho D., Munson P.J., Young L., Wulfkuhle J., Petricoin E.F. 3rd. (2003) Protein microarrays: meeting analytical challenges for clinical applications. Cancer Cell 3, 317-325.

[9] Hoving S,. Gerrits B., Voshol H., Muller D., Roberts R.C., van Oostrum J. (2002) Preparative two-dimensional gel electrophoresis at alkaline pH using narrow range immobilized pH gradients. Proteomics 2, 127-134.

[10] Von Eggeling F., Gawriljuk A., Fiedler W., Ernst G., Claussen U., Klose J., Romer I. (2001) Fluorescent dual colour 2D-protein gel electrophoresis for rapid detection of differences in protein pattern with standard image analysis software. Int J Mol Med. 8, 373-377.

[11] Lopez M.F., Mikulskis A., Golenko E., Herick K., Spibey C.A., Taylor I., Bobrow M., Jackson P. (2003) High-content proteomics: Fluorescence multiplexing using an integrated, high-sensitivity, multi-wavelength charge-coupled device imaging system. Proteomics 3, 1109-1116.

[12] Sanchez J.-C., Appel R.D., Golaz, O., Pasquali C., Rivier F., Bairoch A., Hochstrasser, D.F. (1995) Inside SWISS-2DPAGE database. Electrophoresis 16, 1131-1151.

[13] Appel R.D., Bairoch A., Sanchez J-C., Vargas J.R., Golaz O., Pasquali C., Hochstrasser D.F. (1996). Federated two-dimensional electrophoresis database: A simple means of publishing two-dimensional electrophoresis data. Electrophoresis 17, 540-546.

[14] Appel R.D., Sanchez J-C., Bairoch A., Golaz O., Miu M., Vargas J.R., Hochstrasser D.F. (1993) SWISS-2DPAGE: A database of two-dimensional gel electrophoresis images. Electrophoresis 14, 1232-1238.

[15] Appel R.D., Sanchez J.-C., Bairoch A., Golaz O., Rivier F., Pasquali C., Hughes G.J., Hochstrasser, D.F. (1994) SWISS-2DPAGE database of two-dimensional polyacrylamide gel electrophoresis. Nucleic Acids Res. 22(17), 3581-3582.


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         Revised: 05/12/2007