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because the two fill layers have different colors.
Your two squares are not the same colour.
The yellow channel in the right hand square is at 100%. The yellow in the left 99% .
The maths for blending each channel in colour dodge is Background/(1-Foreground). In the case of CMYK the layer values are inverted before the maths and the result inverted after.
It all works smoothly until the foreground layer is 0% which inverted is 1 and the background is 100% which inverted inverted is 0. That results in maths which is 0/(1-1) = 0/0 which gives
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because the two fill layers have different colors.
Copy link to clipboard
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Your two squares are not the same colour.
The yellow channel in the right hand square is at 100%. The yellow in the left 99% .
The maths for blending each channel in colour dodge is Background/(1-Foreground). In the case of CMYK the layer values are inverted before the maths and the result inverted after.
It all works smoothly until the foreground layer is 0% which inverted is 1 and the background is 100% which inverted inverted is 0. That results in maths which is 0/(1-1) = 0/0 which gives an error for which 0 is used and is then inverted to become 100%. i.e. the channel remains at 100%
Dave