Patrick Lam wrote:

> Note that we use the formula (red+green+blue)/256 for grayscaling (at
> least in PS output), but that's not the correct ratio that corresponds to
> human colour perception.  What is the correct ratio?  A quick google
> search didn't turn up the result.

Providing the right search terms it did. :-)
"human color perception RGB grayscale"

For example, GIMP apparently uses:
luminance, Y = 0.30 R + 0.59 G + 0.11 B.

But this is a much larger area, depending on you monitors gamma and such. We
don't really want to go there.

For more info you might look for the "Color space FAQ".

/Mike


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