Do you know how each of the red, green, and blue channels is calculated when opacity of a layer is used please?
I am wondering if it is, if opacity is expressed as a value p in the range 0.0 to 1.0, if there are n layers, as
x = p * x(i) + (1 - p) * x(i - 1)
Alas, I cannot use square brackets, as the forum software treats them as markup.
and recursively back to the background colour x[0]..
In my picture, a few posts back, (r, g, b) for the blue background is (128, 128, 255) at 100% opacity.
Then each of the five yellow areas have (r, g, b) as (255, 255, 0) at 20% opacity, so p=0.2.
So if my guess at the formula is correct, then
(r, g, b) for the single yellow layer on the blue would be about (153, 153, 204)
Using Paint to look at what is the colour gives (153, 153, 204), so it looks like my guess at the formula might be correct, at least for just one semi-opaque layer upon an opaque layer.
William