I've been commissioned to do some Poser illustrations for a company and they are wanting the images submitted in CMYK .jpg format.  My question is what is the best way to go about doing this to ensure (as best as can be) that the colors will be right?  When I bring a .tif file into PS should I check don't color manage and then click the CMYK thingie or what?  Thanks!

if they want cmyk you need to know the profile before you convert the rgb. all .jpg images save as RGB, as far as i know it's how jpg compresses the image information... i think

If you don't colour manage the conversion won't have a (predictable) starting point - treat your colour management as usual, but make sure you have the right CMYK profile selected as you work and check for out of gamut colours is the advice I've seen most often.

PS has no trouble saving a CMYK jpg, though I'm surprised they aren't asking for a Tiff or other lossless format.

That does make sense,  cmyk should be one of the  the last things most ppl do to an image. . . understanding what 'gamut" is and how your images e spectrumn of colours can fit  into each gamut  is the  tricky part... whatever design is done  it's often unfamiliar to make an image in cmyk mode, and often the interaction of photoshp blending modes, lighten, multiply and filters will not quite work the same... the  jpg compression would be the main factor,  --- if they use a program that is up-to-date to handle that cmyk,jpg  .. after it's opened what are they going to do with it...

I've done work for this company before and submitted as a CMYK .jpg as they requested.  Since they are contracting me again, I suppose whatever I've done isn't too bad or they wouldn't have asked again.  They are adament about the .jpg format (I don't know why).  The language barrier is a real challenge so it's hard to say what's on their minds...LOL.  Something else I've noticed is that when I create and save an image in PS and then open it in PSP the colors are nasty to say the least.  It's just really hard to get something close to universal. 

Something else I've noticed is that when I create and save an image in PS and then open it in PSP the colors are nasty to say the least.  It's just really hard to get something close to universal

Open Photoshop and go under View>Proof Setup>Custom>Device to Simulate dropdown menu - click on the little arrow and scroll down. Down the list past all the "DotGain" settings you'll find a large list of names - somewhere in there will be either the name of your monitor's model number, a name referencing specifically YOUR MONITOR, or if you've color calibrated your monitor and given it a name, choose THAT (this is the best one) - I've got mine named MonacoLCD01. This should be accurate going from PS to PSP (assuming you've done something similar in PSP - or it's your monitor's color space by default).

after it's opened what are they going to do with it...

CMYK is used ONLY for color seperation printing - magazines, brochures, publications, etc. It is a direct formula/percentage for the printer to go by to know how much of each specific ink (Cyan, Magenta, Yellow, and Black) to layer in order for the colors to be correct. RGB doesn't have this infrmation built into it, and it doesn't have an equation for Black (in case you're wondering why they don't just go by the opposites of RGB which are Cyan, Magenta, and Yellow - it's got no Black reference).

You don't need profiles - and you'd have to have whatever profile THEY are using or it's useless. All you do is open your image in RGB (there's more color info in RGB), do ALL your corrections and alterations, and the last steps (yes, multiple) are to go to Image>Mode>CMYK Color.

There will be a color shift (particularly if you have vibrant colors), and then go to your Channels Tab (it's parked alongside yor Layers Tab typically at bottom right of the screen), and click on BLACK. Your image will then only display the Black - click the little eyeball next to the top CMYK layer and it'll all come back but you're working ONLY on the Black layer. Bring up your Levels (Ctrl/Cmd+L) and adjust your black AND white ends until you get something you like - then click back on the CMYK layer to make them all active.

Save your image under a different name and you're done. The best you can hope for (given this is a COMPLETELY different color space and display) is for it to be "close" - it'll never perfectly match, but it'll look pretty close.

IF YOUR VIBRANT COLORS ARE NOT VIBRANT ANYMORE is when you'll have a lot of hair-pulling fun. If this happens, post the image and I'll give you further instructions to work with.

Good luck!
-Lew ;-)

Thanks Lew, that's very helpful information!

I am wondering if perhaps your printer is asking for a CMYK separation as *.jpg, rather than a color conversion?