PNG export from CMYK colours: wrong colours

[Wosven]

Hi,

There's a wrong conversion of color from CMYK document when exporting to PNG if the default option "same ICC profile as document" is selected.

Red colours items end up being orange.

Original colours:

Bad conversion:

Original PDf document in CMYK: White lines6.pdf

[walt.farrell]

PNG does not support CMYK. It is RGB or grayscale, only. See, for example, this Wikipedia article.

You will need to export as RGB. Ideally, I suppose, Designer would recognize that conflict and refuse to do the export in CMYK.

[Wosven]

I know this @walt.farrell and I don't expect to have a CMYK PNG, but there's a colour conversion here that's problematic.

When I export (a lot) of documents or part of them created in CMYK to PNG in ID, the colours are respected, red doesn't end up orange

The default behaviour for AD/AP/APub in this case should be different and not try to convert colour if the document is CMYK.

[walt.farrell]

But you must convert the color to RGB, if you want to see accurate colors in the resulting PNG file. Possibly ID is doing that automatically.

Because PNG does not support CMYK, anything that reads a color PNG file will assume it is RGB. If it was saved using the CMYK color values (as you requested), then the next program to read the PNG file will interpret the color values incorrectly.

It would be like Assigning a different ICC profile, rather than Converting to a different ICC profile. (Though Assign is not possible in Affinity when changing from CMYK to RGB or vice versa.)