# How to derive percent color in a photograph?



## awk004 (Jan 12, 2010)

Hi, 
     I'm new and am by no means an expert at digital photography.  I have taken a series of photos for a research project in the same lighting and at the same distance.  I would like to derive the percentage of green in the photos to use for comparison.  I have CorelDraw X4 and Adobe photoshop CS4.  Is there any method to get the percentage of select colors from these photos? 
Thanks for any advice, 
AWK


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## HikinMike (Jan 12, 2010)

I'm using CS2...

Use the 'Eyedropper Tool' and select the area. Then select the 'Color Picker' and make sure you don't check 'Only Web Colors'. You should be able to see the RGB and CYMK percentages.


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## KmH (Jan 12, 2010)

I'm only seeing CS4 defining the percentages of CMYK, and not RGB percentages. Plus it is only giving those numbers for the pixel under the cursor with single pixel selected.

I don't think you can select an area and get what it is you want as "green".


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## awk004 (Jan 12, 2010)

Is there any program that allows you to get percentages per unit area?
Thanks


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## HikinMike (Jan 12, 2010)

KmH said:


> I'm only seeing CS4 defining the percentages of CMYK, *and not RGB percentages*. Plus it is only giving those numbers for the pixel under the cursor with single pixel selected.
> 
> I don't think you can select an area and get what it is you want as "green".



I didn't mean to say RGB as percentages, just numbers. :blushing:




awk004 said:


> Is there any program that allows you to get percentages per unit area?
> Thanks



I'm not sure I understand.


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## awk004 (Jan 12, 2010)

A program that would allow me to highlight an area of a photo and then analyze the highlighted area to return a percentage of amounts of colors.  
Thanks so much for the help


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## KmH (Jan 13, 2010)

awk004 said:


> A program that would allow me to highlight an area of a photo and then analyze the highlighted area to return a percentage of amounts of colors.
> Thanks so much for the help


How are you going to define "color"?

In RGB each "color" is a combination of Red, Green and Blue, each somewhere between the values of 0 and 255. I would think the best a program could do is average an area.

In CS4 you can select the color sampler tool and set it to sample an area 101 pixels by 101 pixels.

Pure Red would be 255, 0, 0.
Pure Green would be 0, 255, 0.
Pure Blue would be 0, 0, 255
Pure White is 255, 255, 255.
And Total Black is 0, 0, 0.
Diferent tones of grey have all three RGB colors equal 100, 100, 100 would be a shade of gray. A lighter shade of gray would be 150, 150, 150.

Good luck with your quest.


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## awk004 (Jan 14, 2010)

Thanks everyone for all the help. 
Awk


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