Converting RGB to CMYK and keeping adjustment layers acurate

[eloy]

Customer supplies an RGB layered file with multiple adjustment layers. When converting to CMYK, Photoshop looses the adjustment layer and its data. How can we retain these RGB layers correctly. Can we convert and apply these layers in CMYK???? Is there a work around or not??? :roll:

[almaink]

Flatten or merge the layers in RGB mode. Then save in a different name as a tif or whatever photoshop format you use. That way you have the original and the one you will use. Most stuff done in RGB will not transfer to CMYK anyway as process just doesn't have the same color spectrum as the RGB color space. I've been converting from RGB to LAB first then to CMYK with good results on files like you describe. Heres a link on LAB.
http://www.creativepro.com/story/feature/12869.html

[eloy]

Hey,
Thanks for the info. Its to bad that most of our 1 sheet customers give us an RGB photoshop layered file as well as an RGB color proof, then they expect us to match the RGB proof. They should know better, but I guess they still expect miricles.
I will sure give the LAB color to CMYK a try and see if it works with our work flow. Thanks again.

[adobewankenobe]

any colour space change involves moving to LAB then to the desired colour space, so the change to LAB as an interim step is a waste of time. The only common denominator between all colour spaces is Luminoscity, so if the colour is less important than the luminoscity, you can choose to keep the adjustment layers purely for tonal control once moving to CMYK. If the colour is critical, you will be able to select the flatten image option when you use the convert to profile command. Determining the difference between flattening and not flattening during conversion can be previewed while the convert to profile window is up, by ticking the preview button on and off.

The statement about CMYK not having the same spectrum is basically true, but if you know what you are doing, and many don't, adjusting RGB colour whilst simulating the CMYK print destination in Photoshop will show you the precise CMYK breakdown that will result upon conversion, whilst you are still in RGB.

Your very last step can then be a conversion, or if you use InDesign, and your desired conversion space is the same as the CMYK colourmanagement settings in Indesign, let Indesign do the CMYK conversion, and don't flatten the Photoshop file at all.