This might be of interest to CCD users...

This is the procedure for doing Kunihiko Okano's DDP technique in MaxIm DL; it
works equally well on monochrome and color images:

1. Use the Information window to measure the average background level.
2. Use the Pixel Math command to subtract that background level from the
image.
3. Duplicate the image
4. Blur the duplicate image using the FFT filter command. Select Low Pass,
100% Weight, Cutoff 25 (this can be adjusted for best effect).
5. Guess at a value for "a". For a good starting point, use the Information
window to measure a middle intensity level in the image.
6. Add the value "a" to the blurred image using the Pixel Math command.
7. Use Pixel Math to divide the image (from step 2) by the blurred version
(from step 6). Set "Add Constant" to 1.
8. Adjust the screen stretch for a pleasing display.
9. Use the Stretch command with "Linear Only", "Input Range" set to
"Screen Stretch", and "Output Range" set to "8-bit" or "16-bit".

I'll be adding DDP to an upcoming release of MaxIm DL; it will then be possible
to do it all in one step.

Doug

--
Doug George
Diffraction Limited / Cyanogen Productions Inc.
Phone: (613) 225-2732
Fax: (613) 225-9688
http://www.cyanogen.com

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