Calculating a percentage of black pixels?

JN
Posted By
Joe_Nevin
Aug 23, 2006
Views
921
Replies
1
Status
Closed
I’m looking for an easy way of calculating a ratio of black to white pixels. I work for a specialty printer, and as such we use special (re expensive) inks. I have a gray scale Photoshop file that shows the area that gets this special ink. I want to be able to calculate a percentage of ink coverage, based on the ratio of black pixels to white pixels. The only thing close I have come up with so far is placing a grid on the file and counting, but obviously that is kludgy. Is there a simple way of selecting all the black and finding out how many pixels are in that selection? From there I can figure the percentage based on total pixels in the file. Any and all help is greatly appreciated.

Joe
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Carl_Stawicki
Aug 23, 2006
The mean of the histogram is the average coverage. You just need to translate the value into an ink percentage. So a mean of 127/128 would be ~50% ink coverage.

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