Ok, dudes and dudettes, here's the deal on CMYK.
I work in the print industry, so, I gotta chime in here, i'll try to keep it simple.
(NOTE THIS MOSTLY APPLIES TO LITHOGRAPHIC PRINTING - DIGITAL IS A BIT DIFFERENT)
CMYK VS. RGB Let's say this is the ENTIRE spectrum of colors:
{---------------------------------------------------------------------------------------------------}from infrared to ultra-violet.
The human eye can see this much of that spectrum:
{----------------------------------------------------------------}It can see a wide range of the ENTIRE spectrum of colors. (Birds can see an even wider range than humans I think, and dogs n cats can see less of the full range, but that's off topic...).
RGB (RED-GREEN-BLUE) as you may know is how a monitor/TV displays colors
It can display this much of that spectrum:
{--------------------------------------------} it has a really wide color range, but of course cannot display the full range of hues that the eye can see.
Then there's CMYK standing for CYAN-MAGENTA-YELLOW-BLACK (yes the K stands for black because blue already took the B)
CMYK can print this much of that spectrum:
{----------------------------}Those 4 colors (CMYK) come together in offset/litho printing using halftones/ben day dots to create ALL of the colors you see in print, except for SPOT colors, aka Pantone colors, which are used to get colors outside of CMYKs range, aka GAMUT.
CMYK printing works kind of like painting where you can mix the primary colors to get almost all of the other colors.
So as you can imagine, CMYK has it's limits, say you want a really intense red to print, well the only thing you have on a 4-color press is the pinkish-looking Magenta, and no matter how much of the other three colors you add to Magenta, it's not going to get any more red.
That's where the spot/pantone colors come in.
And that is why many RGB images that print CMYK come out looking like ass, many of the colors a monitor can display are "out of Gamut", or out of range of what the printer can print.
You kinda have to know how a printing press works to understand fully, but the typical print job prints with 4 colors via 4 seperate towers that each hold 1 color of Ink, so if you add spot colors it becomes expensive because you have to throw another tower into the mix.
Rule of thumb is that, like Zach said, extreme darks and lights suffer. And that muted colors come out better and more intense colors suffer.
Dark and light is not as hard to fix, you can usually always go darker or lighter with the 4 colors, but ink will never get more intense (aka chroma) than it is unmixed, and unmixed = only the 4 choices, CMYK.
.
COLORS THAT ARE ESPECIALLY HARD TO MATCH ON PRESS:INTENSE REDS
GREENS
INTENSE BLUES
ORANGES
SO KNOW YOUR COLORS WILL SUFFER ON PRESS IF YOU HAVE A LOT OF THESE.
always a good idea to find out as much as possible about the printer/press that will re-produce your work, then you'll have a better Idea of your limitations.
I know from reading the DC coloring/lettering book that most pros color their stuff in CMYK mode, so that they know what they will get in the finished product. That's a great book for comics coloring info BTW
Digital printers are kinda different, some of them have extra inks in addition to CMYK, and that's why they can print RGB better.
But in general, these rules still apply, even with extra ink colors, the printer will never be able to match ALL the colors on your monitor.
In photoshop it's tricky if you use filtters cuz many of them only work in RGB, but if you goto the view mode, you can work in RGB while previewing in CMYK.
Many printers will convert your files for you, but then you don't have any control over how it will come out. Proofs are infinitely helpful, but sometimes a digital proof cannot be matched on a 4color litho press.
Hopefully this is helpful to some of you.
Damn, I got kinda complex, well if anyone has any
let me know i'll try to explain better.
AND THE LINK WILLY D POSTED
http://www.cambridgeincolour.com/tutorials/color-space-conversion.htm GOES EVEN DEEPER ON THIS STUFF AND ALSO HAS PICTURES SO CHECK IT OUT!!
Spilt Milk
King vs. Morrigan
@ 7:31 PM May 10th