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I’m trying to determine the average RGB hue of several samples of monochromatic painted canvas. I have scanned each piece, but of course the hue of each pixel in the canvas is different, depending on whether I choose pixels from the highlight, shadow, et cetera.
My solution in this color mapping quest was, I thought, to select a sample of the scanned canvas in Photoshop, then use the “Cutout” filter to sort of average them all the pixels together into one solid hue, one that is no longer jumbled by the texture of the canvas (no matter how much I zoom in). Alas, I don’t think the “Cutout” function is accurate enough...it renders a bright lemon yellow as maize, a nice raspberry as mulberry, and so on. The hue seems a bit skewed, and with less chroma than I perceive in the untouched images. Since I’m trying to map real color samples to RGB in order to compare gamuts of possible primaries, I need a bit more accuracy.
To the point: is there a way, in Photoshop or some other affordable program, to determine the average hue of a mostly-monochromatic piece? I can’t find anything else that will render pixels all equally, and “Cutout” is all I’ve thought of so far. Thanks in advance for your help (I hope)!
My solution in this color mapping quest was, I thought, to select a sample of the scanned canvas in Photoshop, then use the “Cutout” filter to sort of average them all the pixels together into one solid hue, one that is no longer jumbled by the texture of the canvas (no matter how much I zoom in). Alas, I don’t think the “Cutout” function is accurate enough...it renders a bright lemon yellow as maize, a nice raspberry as mulberry, and so on. The hue seems a bit skewed, and with less chroma than I perceive in the untouched images. Since I’m trying to map real color samples to RGB in order to compare gamuts of possible primaries, I need a bit more accuracy.
To the point: is there a way, in Photoshop or some other affordable program, to determine the average hue of a mostly-monochromatic piece? I can’t find anything else that will render pixels all equally, and “Cutout” is all I’ve thought of so far. Thanks in advance for your help (I hope)!
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Tucson
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Re: Blending or averaging pixels using “Cutout” or ???
Thu, July 31, 2008 - 6:19 AMTry the median filter.
You can also change the setting of the color sampler (eyedropper) to something like eleven-by-eleven instead of a one pixel specimen. -
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Averaging pixels
Thu, July 31, 2008 - 11:51 AMThank you...I didn't realize the eyedropper could select more than one pixel. My book (I have 7.0) says it will go to a 3 x 3 or 5 x 5 average, and even the xx x 11 you mentioned isn't really large enough, but I'm happy to know about this tool. Thanks!
I did find, after staying up late and obsessing, that if I change the image size to 1 pixel x 1 pixel, the resulting hue/saturation etc. seem to be the average of all the pixels. Then I bring the size back up to, say, 50 x 50, so I have a large enough sample to compare onscreen with the untouched sample.
I think the decrease in chroma is an interesting thing...of course if you add a bit of black to a bright yellow, you're going to get maize, so this is what happens when you average the pixels on a scanned piece of bright yellow, because the dark shadows are then mixed in. What's interesting is that our perception of the fabric (and the scan of the fabric, un-averaged, showing the texture) yields a bright yellow...our brain does not average the pixels, but seems to rely more upon the highlights for its perception of chroma. Interesting. -
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Re: Averaging pixels
Thu, July 31, 2008 - 11:53 AMOops, of course I meant "11 x 11," not "xx x 11."
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