Photoshop Gurus!

[g.]

All you Photoshop Gurus (e.g. Steve, George, Pat, Boyd, etc.)

Does anyone know how to take an image and automatically count the number of pixels of a certain color?

For example I have a fingerprint image with green, yellow, and red markings on it. I would like to know how many green pixels are present, yellow pixels, etc. I will take any metric as long as I can compare green apples to yellow apples to red apples.

The problem is slightly more complicated in that all the images may not have exactly the same shade of red (it can vary abit depending on the background, which is greyscale fingerprint ridges).

Your help is appreciated. Post here or to: glenn.langenburg@state.mn.us

Thanks in advance.

(PS-if it matters, I only have a copy of CS with me...if later versions are needed, please specify. thx.)

g.

[David Fairhurst]

I'm not a guru, but for a quick answer you can try looking at your histograms.

They will show you how many pixels of every given value of hue, saturation and luminosity you have.
posterising or reducing the colour depth of the image will force similar value pixels into larger groups.

[g.]

Thanks Dave, I came back here just to tell folks, nevermind. I spent 2 hours trying to get it, posted to the board, and 5 minutes later figured it out. My HISTOGRAM window had a tiny arrow to "EXPAND". Once expanded there it was. And as you say, it says how many pixels are selected. Once I separated my colors into layers, it was easy to calculate. And accurate. Fantastic....

Now comes the next 8 hours of separating, selecting and counting....

I need a research assistant!

g.

[Steve Everist]

Glenn,

Did you notice that there's also an "all channels" view to the Histogram? This separates them into separate histograms all visible at one time. This is in CS3 - not sure about CS.

[gaganforensics]

Perhaps, you can open the image in the photoshop

the go to window drop down menu and select INFO or alternatively press F8

the u can move the cursor over the image and the values of different shade, pixel values will come in terms of

RGB CMYK WH etc.


Hope it helps

with regards
gds