hello all, if your reading this, thanks for your time. As in my subject heading, i would like to use photoshop 7 for windows to estimate the percent of an entire image taken up by a color (or range of colors). Specifically, i am assessing the amount of green ground cover exibited by plant as a percent of the total ground cover (the whole image). There may not be an easy way to calculate this, but then again there may. I would like to be able to select a range of greens from one image to do the calculation on. Can anyone be of help with this problem?
Thanks, Buffy
#1
Select > Color Range, and then Histogram.
#2
Buffy,
The trouble with using Color Range is that you have to decide on a fuzziness value which, for your purposes may be, well, fuzzy. If you get by that, then you have to contend with "partially" selected pixels. I think those above 50% selected get counted by the histogram.
It may be better to skip the Color Range feature and, instead, visually select what you consider green areas. The histogram will count all pixels within that selected area. Dividing by the total number of pixels gives you the "green" percentage sought.
George
#3
If partially selected pixels are a problem, just go into Quick Mask mode, and use Threshold. Or Curves or Levels, if Threshold's too drastic.
#4