Jason Wong <7jw6@qlink.queensu.ca> wrote:
>Hi, I'm trying to figure out how to use Photoshop
>for scientific image analysis purposes.
Photoshop has some "enhancements" that makes it is rather difficult to
utilize it for scientific purposes.
>I need to analyze is the intensity in certain brain
>regions created by a specific staining technique.
What is it that gives the "intensities"? X-ray film or something else?
>I was thinking of doing is using the square marquee
>of Fixed Size to anaylze a square from Region A, and
>compare that to a same area in Region B. What confuses
>me the most is if I do Image --> Histogram, the value
>for Mean seems to be inversly proportional to the
>staining intensity.
The relation depends on the working-space gamma, among other things.
>i.e., if the region is darkly stained I
>get a small Mean value and vice versa.
Yes, the relative whitepoint is RGB=255,255,255, from there on it gets
darker and darker as you approach to level RGB=0,0,0.
>Is there a specific formula I would use in order
>to determin the relative optical density of a
>certain region?
Yes there is but one needs to know what the source is, it has to have a
known relation to density in the first place.
Timo Autiokari
http://www.aim-dtp.net