Superposition de calques monochromes d'opacités variables
For a monochrome layer x of opacity 0< o_x<1 placed on another monochrome layer of opacity 1, the result given by the standard formula is Π( C_φ)=1+∑_n=1^2(2-n-(-1)^no_χ(φ+1))(χ(n+φ-1)-o_χ(n+φ-1)), the formula being of course explained in detail in this paper. We will eventually deduce a very simple theorem, generalize it and then see its validity with alternative formulas to this standard containing the same main properties here exposed.
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