Difference of color and contrast of the photo

contrast
color-analysis
roi
Tags: #<Tag:0x00007fd5484fb6e8> #<Tag:0x00007fd5484fac20> #<Tag:0x00007fd5484fa860>

#1

Dear All,

I would like to find the difference of the color and contrast along the X axis (See the attached figure).
I only know the Grey Scale measurement.

Is there any other method to find the different of contrast along X-axis ?

Best Regards,
Yannapol S.


#2

Hi Yannapol and welcome to the forum :slight_smile:

I don’t see any color in the image you attached, is this a western blot (or analogous)? If so, have you looked at the Analyze >> Gels functions?

Maybe you can elaborate on what this is, what you want to measure and why? And if you can share an original image for us to experiment with that would be helpful. :slight_smile:

Best,

Sverre


#3

I would be interested in ways to measure color as well. I am currently working on a dataset (see another recent thread here) and planning on using the grayscale measurements as proxies of pigmentation, but would be happy to compare the final results with color values if this kind of measurement is possible.


#4

If you setup your display to the conditions of IEC 61966-2-1 sRGB then you can convert standard sRGB values to XYZ or to Lab* values. From the Lab* coordinates, you can compute perceptual chroma C* and hue angle h. Unfortunately, the color management plugins, based on a Kodak color engine are buggy and do not do this correctly so you will need to lookup on Wikipedia the equation for this conversion or use a website like that of Bruce Lindbloom (www.brucelindbloom.com) where these calculations are fully documented and he has a calculator to test and validate your computations. Contrast is normally reported as the fraction of the total gray scale in an image. Y / (Ymax - Ymin) or sometimes just Y / Ymax.