Colors in JPGs with CMYK are not parsed correctly

[photopea]

Hi, I have several CMYK files, where I get incorrect colors after decoding them with pdf.js

I discovered, that it could be fixed by inverting the input. At line 1051 (and four following lines) https://github.com/mozilla/pdf.js/blob/master/src/core/jpg.js#L1051 we should have Y = 255-data[i] and vice versa.

I would like to find the original author and ask him about this part of the code. I could not find any CMYK JPG, for which the current code would work. I only found 3 JPGs, for which my "inverted" code works.

jpg11 1
channel_digital_image_cmyk_color
insta

[photopea]

Guys, I created a pull request. It solves the problem and does not break anything (but only for my set of testing JPGs). #10029

[timvandermeij]

Fixed by #10031.