CMYK issue: Krita or Cyan

[rich2005]

(01-04-2025, 02:50 PM)enrimoore Wrote: yes RGB is much better, but I "must" use CMYK for the printer.

Just checking I hope you do not expect your RGB image to be the same in CMYK colorspace

Because: quote Some RGB colors that you can see on your monitor (in particular, blue, green and all bright vibrant colors) cannot be printed and/or replicated with standard CMYK inks. Keep in mind that, when creating a file for print, you should always make the original file in CMYK color mode before starting to work on it.

Quote:Difference between jpg and tiff is about 93%  (lower than in all my tests, but not much)

Just out of interest, how are you measuring that. Here using ImageMagick

Code:

magick compare -metric RMSE cmyk.jpg cmyk.tiff null:

I get about a 2% difference between the same file from cyan exported to jpeg then tiff. I put the difference down to jpeg compression artefacts. I get the same 2% converting from rgb to cmyk using my ancient PS7

Quote:Anyway, Krita and Cyan give exactly the same output. Surely they both use same conversion tool.
I need an acceptable CMYK conversion tool, without buying Photoshop, which I don't need at all. 

I think you are going to be stuck. Gimp / Krita / Scribus (another option) originally come from linux and will use the same library files.

Quote:I am using Nx Studio on raw exporting a tiff, then Gimp for assembling 3 photos and completing a book cover.   

I don't know if other options are available. And if they are at least acceptable, too. 
Advice welcome
enri

Nikon images ? You could ask the question on https://discuss.pixls.us/