Flicker Vignette - How do I measure background intensity near a spot?

This vignette shows how do you can measure background intensity near a spot. The background estimate is computed under the circular mask. A separate background estimate is defined for the left and right images. Note the background measurement is used for computing background corrected density for measurements made by circular mask (C-M) and by region of interest (C-R). It will be used for multiple measurements until you change it. If you are measuring a series of spots by circular mask, then if you change the background intensity measurement, it will be associated with all spots measured since then and saved in the spot list until (or if) you change it again.


  1. To show the circular mask, make sure (View | Set view measurement options | Checkbox
onView measurement circle) is enabled.
  2. Select the new circular mask size in the measure circle (diameter) slider. Note: the NxN is one of 1x1, 3x3, 5x5, ..., 51x51 options which is the size of the rectangle enclosing the circular mask.
  3. Select the spot you want to use to estimate the background by clicking on it in either the left or right image.
  4. Capture the backround estimate using the (Quantify | Measure by circle | Capture background (C-B)).

Setup for the demo

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Contact us     Flicker is a contributed program available at open2dprot.sourceforge.net/Flicker          Revised: 01/19/2004