DIC (Nomarski) image background correction

[Ralph Common]

Image division using a blank background image works very well for
correcting uneven illumination in brightfield microscope images, but it
does not work for DIC images.  I believe this is because a DIC image has
areas that, unlike a brightfield image, are brighter than the
background.  Has anyone written a plugin or macro that would correct
uneven illumination and color shifts in DIC images?  It seems like it
should be possible to compute how each pixel of a blank background image
(made from an empty area of a slide, under identical conditions) departs
from uniform gray, and apply the appropriate correction to the actual
images.

Ralph Common

[Michael Schmid]

Hi Ralph,

did you try to use Gabriel's macro (with the Calculator Plus) and replace the 'k1=255' with a lower value, e.g. 'k1=128'?

http://imagejdocu.tudor.lu/doku.php?id=howto:working:how_to_correct_background_illumination_in_brightfield_microscopy

For grayscale images (also 16 bits), you could also use my macro posted yesterday
  https://list.nih.gov/cgi-bin/wa.exe?A2=ind1205&L=IMAGEJ&F=&S=&P=105906

Michael
________________________________________________________________
On May 23, 2012, at 01:43, Ralph Common wrote:

> Image division using a blank background image works very well for correcting uneven illumination in brightfield microscope images, but it does not work for DIC images.  I believe this is because a DIC image has areas that, unlike a brightfield image, are brighter than the background.  Has anyone written a plugin or macro that would correct uneven illumination and color shifts in DIC images?  It seems like it should be possible to compute how each pixel of a blank background image (made from an empty area of a slide, under identical conditions) departs from uniform gray, and apply the appropriate correction to the actual images.
>
> Ralph Common