PixelValue will extract the channel values at a certain pixel. It returns a vector of numbers, not a colour. Is there a simple way to extract the colour of a pixel as an expression that is ColorQ? The image could have an arbitrary colour space.
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Perhaps something like this:
ColorConvert[
PixelValue[im, pos],
OptionValue[Options[im], ColorSpace] -> ImageColorSpace[im]
]
where im is an image and pos is a pixel position, e.g., {100, 150}.
The basic idea is to use ColorConvert to automatically get the correct head for the image's colour space (e.g. RGBColor or CMYKColor). For this, we need the syntax ColorConvert[list, colspace1 -> colspace2] where colspace1 should define the interpretation of the values in the list.
answered May 6, 2020 at 15:00
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$\begingroup$ Could you explain the second argument? To me the left-hand side of the arrow seems like it should return the same as the right-hand side. What is the difference? $\endgroup$– C. E. ♦Commented May 6, 2020 at 15:09
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1$\begingroup$ @C.E. Sorry, I should have been more verbose (I'm trying to get something working in parallel to asking...) What I am still confused about is the impact of the
ColorSpacebeing aColorProfileDataobject. I was trying to deal with this. For example, take the first example from theColorProfileDatadoc page. The version I showed here effectively doesColorConvert[{a,b,c,d}, ColorProfileData[...] -> "CMYK"]. I think this is the correct interpretation of the colour. We cannot have aColorProfileDatain a colour object (likeCMYKColor), so on the RHS I just used"CMYK". $\endgroup$– SzabolcsCommented May 6, 2020 at 15:21 -
$\begingroup$ Any feedback about the use of
ColorProfileDatais welcome ... $\endgroup$– SzabolcsCommented May 6, 2020 at 15:21 -
$\begingroup$ @C.E. I am thoroughly confused. New question: mathematica.stackexchange.com/q/221271/12 $\endgroup$– SzabolcsCommented May 6, 2020 at 15:33