Conversion from RGB to CMYK

[psphufi]

Hello,

I have converted an image from RGB to CMYK as follows:

Installed the profile ISOcoated_v2-300_eci.icc and integrated it into the colour workspace.
Then channels separated: CMYK, opening 4 different images in black and white, each named cyan, magenta, yellow and black.
After that I chose: Image - Combine channels - CMYK combination. The finished picture does not differ in any way from the original picture! Shouldn't it look different on the monitor?

So far I had used the programme https://www.rgb2cmyk.org/en.html and selected the above profile: The difference was clearly visible! Unfortunately, this service has not been working for some time, so I have to use PSP.

Can I trust that my images will still be printed correctly by the printer? Or have I done something wrong in my work?

[LeviFiction]

Yes, there should in general be a difference so long as the RGB color doesn't fall within the gamut of the CMYK color and needs to be shoe-horned in. This can often lead to less vibrant colors. Or slight color shifts. But that depends on the profile and the image.

Also look at your Color Management. Are you already soft-proofing? If so you might not see a difference because it's already simulating what that would look like printed without needing to soft-proof with Split and combine channels option. By the way, if you want to avoid splitting and combining, you can Save as a TIFF file and set the file options to save as CMYK with your currently selected CMYK profile. Then when it's reopened in PSP it'll convert back to RGB letting you see the effect.

[psphufi]

Excellent! The tip of saving the image as a TIFF with the CMYK profile option is really great! Now I can also clearly see the difference.

Thank you and have a nice time
Norbert

[psphufi]

There is still a big problem!

When I insert the pictures in my book, which I create with Open Office, these pictures are only visible for a moment. As soon as I click somewhere else with the mouse, the pictures disappear again! This never happened with the conversion programme I mentioned before...

It seems that Open Office is interfering with something about the images. What could it be?

2.jpg

1.jpg

[Jean-Luc]

Do not convert your images to CMYK. Leave them in RGB.
Professional printers print in CMYK, but they all have an automatic RGB to CMYK converter.
Even your inkjet printer prints RGB images in CMYK without the need to convert them first.