Adding images together

Hi,

I am writing some software the creates anaglyph images by taking the red component of one image and adding it to the blue & green component of another. By and large this works but when I feed the same image into both sides the image I get out is not the same as I put in. It is a bit too bright and the contrast is down. If I change the “addition” block for a “brightest” block I get out what I put in. However, there are situations where I don’t want to do this and it is really an addition operation I want. I separate the components of the two images using a colour matrix with Red(x)=1 and Alpha(w)=1 for one image and the other Green(y)=1 Blue(z)=1 and Alpha(w)=1 (all others zero). Then add the two images together. Why won’t the addition do what I think it should do?

Mike Cook

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"Engineers know million to one chances happen nine times out of ten..."
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