FrenskeP

Thank you for sharing your ideas about this. Sounds like a reasonable explanation.

I try yo create a luminosity mask from the K channel in color mode CMYK. I convert the document to CMYK. In Channels right click on Composite Black and choose "Create spare channel". The result is a sort of inverted K channel. See the attached files. The first picture is the real K-channel. The second the created spare channel. In other color modes the same procedure gives me a perfect copy of the desired channels. What went wrong? That's the question.

Thanks a lot for the link Dan C.

Hello I'am new here. I use Affinity Photo latest version on an iMac with latest OS. I was wondering why the blendmode difference doesn't work in colourmode Lab? A search on the forum wasn't succesfull. Hope anyone can help me out. Grts. Frans