Re: [microsound] [OT] PhotoShop RGB->CMYK

["scott allison" <lipistal3@xxxxxxxxxxx>]

>>does anyone know of a PS plug that coverts RGB->CMYK i.e., a better
>>algorithm for RGB->CMYK conversion than what is used in PS?

No that I know of.

>that conversion is dependent on many things, and has many variables all 
>which can be controlled from within PShop using conversion curves, or ICC 
>profiles. it really depends what you are tying to accomplish. CMYK for what 
>press? Web? Offset? What kind of paper? If your conversion is leaving the 
>colors looking muddy on screen... it is likely that the original image in 
>RGB contains colors out of gamut... meaning they can never be printed at 
>all in a CMYK colorspace... there are techniques for "rescuing" certain 
>things... (using LAB color space for instance) but without knowing the 
>details... no one can really help you. there is no "formula" for getting it 
>right in every instance for any image for all conditions. to it's credit 
>PShop has an incredibly powerful set of tools for making those conversions 
>possible... in the hands of a knowledgable operator.

Use the info window. once you have converted to cmyk, use the eye dropper 
tool to read the build, the info window will tell you the exact cmyk 
breakdown of every pixel, if you have a pantone cmyk fan then you can try to 
locate a build that matches what you are reading. If you have been doing 
design and production for a long enough period of time, this is less 
important as you start to just know what breakdowns will look like. Also you 
can use the selective color window to then be able to adjust cmyk builds 
globally, ie. you can adjust only the reds, greens, yellows ect... this will 
allow you to de-muddy builds.

So you really have to read the builds and compare to a pantone process fan 
to really see what that build looks like on paper, what you see on screen is 
not really what you get.

Bottom line. there is no simple easy way to just convert and expect to get 
perfect color, way to many vairbles, you could be using a crappy printer 
then there is the issue of dot gain. but I bet for your needs, this is 
probably just a cd sleeve on a typical house sheet, you dont really need to 
worry to much, also your monitor might not be calibarted. I would suggest 
having a match print made.

email me off-list if you need more help.

-scott

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