I'm making a business card in Photoshop and it needs to be in CMYK mode. Now, I'm using a logo on it that I previously made for the client in RGB mode and when I put it into the CMYK mode business card design it desaturates it a little. I'm trying to get my head around whether or not it will print how it looks on my screen (ie desaturated) or how it looks when it's in RGB mode? Because, the colours aren't accurate in CMYK mode so if that's exactly how it will look when printed I will need to adjust the colours to look like they do in RGB mode. Sorry if that doesn't make sense - usually I only design logos and I've never run into this problem before.
Firstly, when you change color modes, you should use Photoshop's
Secondly, the reason people do print designs in CMYK is precisely because it allows them to work in the same color space as the printed result. However, you still need to have 2 things for truly accurate color reproduction:
If you can get the ICC profile from your printer, then you can go to
Though, to be safe, you should also try to get a hard proof or contract proof to make sure things turn out exactly the way you want, especially if it's a large print job for something as important as a business card.
Note: Some printing services prefer that all files are kept in RGB. For instance, Blurb—the self-publishing service—requires all images and print files to be sent in RGB format. Perhaps this is because they also create e-books, or perhaps it's to simplify the process for end-users, but that's how they do things. And the ICC profile they provide for soft-proofing is an sRGB profile.