converting files from cmyk to rgb and/or rgb to cmyk

[seapod00]

When converting a file from cmyk to rgb, I tend to lighten it up a bit using curves in photoshop. but this isn't always a very accurate way to make the conversion. what else would you consider?

And how about for rgb to cmyk?

[wouter999]

Conversion to RGB to CMYK and vice versa is never a good idea. When you start the project, bear in mind the specifications, and work accordingly. That requires some forehand planning, i.e. finding out which printer you'll be using, what the client wants, what technology you have at your disposition. All that considered should be enough to make a decision to go with RGB or CMYK.

[seapod00]

although it's a bad idea, it does have to be done sometimes. so just switching it in Photoshop from one to the other? That's what I tell people. And lighten with curves if going from rgb to cmyk, cuz cmyk darkens things?

[seapod00]

or wuz it lighten with curves if going from cmyk to rgb?

[hothousegraphix]

Actually, in an ideal world conversion would never need to happen, but...there are a multitude of occasions when this has to occur; maybe the client has source material they've provided (say in RGB) and you've been hired to produce a brochure that incorporates this material.

IMHO, I think conversion is an art unto itself...falling under the category of retouching and correction. The image itself, along with the final application will dictate how you proceed. A few things to know, however, are that when going from RGB to a four color process (CMYK) the image will likely loose color intensity - it'll have a duller appearance. Blue's in general are effected the most in this process and seemingly is the most difficult color range to nail down if you're being picky (only my opinion). I think most would agree that it's this conversion (RGB to CMYK) that can drive a designer crazy.

In my experience the opposite is not at all true. The resulting image of a conversion from CMYK to RGB often yields a minimal difference from it's original. This seems to be because RGB has the ability to produce a wider color range - somewhat counterintuitive.