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CMYK vs. RGB

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Redcap
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So I have been expeirementing with my prototypes and I have found if I paint a picture in PS using RGB then print the quality is better than if I paint in CMYK and print. I thought CMYK was suppose to be better, but everything I have seen thus far has shown otherwise.

So what is the deal? Why to printing companies print in CMYK when RGB is more redially available and looks better?

fecundity
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Most printers actually put

Most printers actually put four different colors of pigment on the page: Cyan, magenta, yellow, and black. A CMYK file gives the instructions to the printer in terms of those pigments.

Old school computer monitors actually had three different guns: Red, green, and blue. An RGB file gave instructions to the monitor in terms of those colors.

When you are working with an RGB document and it goes to a printer, the RGB is translated to CMYK. You may get better results by working in RGB and letting the printer translate to CMYK, but it has to happen at some point.

What exactly do you mean by "better results" with RGB, anyway?

Redcap
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When working in CMYK with PS

When working in CMYK with PS the colors are dull and can't get any vibrancy. However, if I work with RGB the colors print great. they are bold, vibrant, and look like the colors on the monitor.

fecundity
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Which "PS" graphics app are

Which "PS" graphics app are you using? (I can think of at least two.)

PFreer
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How about...

hmm, We always paint in RGB and convery to CMYK as needed ( I work as a concept artist and previously as a graphic designer) RGB has a greater gamut than CMYK and is the general reason why one should do all editing and painting in it, then convert to CMYK when required. Often in my previous design life we'd have to seriously manipulate converted CMYK images to come anywhere close to the original RGB image (CMYK really struggles with orange and lime greens). Never send anything to professional print as RGB, the colour outcome will be wildly different from your home prints or screen image...they also look RGBey (kinda hard to describe , but kinda garish in colour and easily spottable to the untrained eye).
The reason why your RGB prints are looking okay when printing from home is probably that you're printing through a desktop printer optimised to print home photos and thus it converts your RGB images to an optimised CMYK format just before it prints: I have experienced the same thing myself.

gameprinter
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Printing in CMYK

Recdap - make sure your monitor is color calibrated. Colors on the monitor will look greatly different than the printed color if the monitor is not calibrated. We have a mouse-like optical USB gizmo that our designers run over the screen. Software then calibrates the monitor based on the feed back.

Even after color calibration, some colors will look different on screen. PMS (Pantone Match Service) colors are notorious for printing and displaying poorly in RGB or CMYK. BTW, PMS conversions to CMYK in orange are especially awful.

As for why printers use CMYK, the short answer is: they don't make RGB ink. More technically speaking, CMYK is color additive and RGB is color subtractive. Thus, RGB works great on monitors (where you start with light) and CMYK works best on paper, where you start with nothing and have to reflect light. (Note: I'm trying to translate from our prepress department's answer on this. My apologies if I've mangled the science!)

MatthewF
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Best Uses for CMYK and RGB

I use RGB for anything I'm just going to print on my own printer: the colors are much more vivid than with CMYK, despite using professional programs (InDesign, Photoshop, etc.) when converting from RGB to CMYK. This is because my color laser printer's CMYK color space is much, much larger than that of a conventional press. Most inkjet printers are the same way.

If you create something in RGB and then print it on your local printer, the printer driver and the printer does the color conversion, retaining as much of the brightness as the device can handle. If you convert to CMYK on the computer first, though, or just work in CMYK, you're working with the CMYK that an actual press can handle. If you intend to go to press then this is essential, as otherwise you'll be in for some really nasty surprises during the conversion in the printer's prepress software before if goes to press, sometimes completely ruining the piece.

So, if you're only going to print locally to your little computer printer, by all means feel free to work in RGB: the end result will probably be much brighter and more colorful (and have more subtle shadings of certain colors, etc.). If you plan to go to press, though, having it professionally printed, definitely work in CMYK*.

If you're working for something that will only ever appear on a computer screen, definitely use RGB, as that's all it can display.

*Possibly worthy of note: for really high-quality printing, there are other press spaces beyond CMYK... one example is Hexachrome, which actually uses six colors on the press and can print much better oranges and greens. However, these processes tend to only be used in really high-quality photographic stuff like National Geographic, and some product packaging. Interestingly, you work in RGB in your documents and then let the RIP do the conversion to Hexachrome.

Aerjen
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To delve a bit into the

To delve a bit into the calibration mentioned before. If you're really eager to get a high correspondance between your screen output and the output of your printer, you have to calibrate your printer as well. Although I wouldn't really recommend this to the average designer, because you can really run into a lot of costs you want to tweak it to the max.

If you just want something comparable you can do it by printing stuff (e.g. a nice overview of pantone swatches and a black to white gradient) and comparing it to your screen. Next you adjust and repeat until you have the desired effect.

If you want to put some money into it, you might want to rent the mousethingy for calibrating your display (I've seen it for €20,- a day). If you think it improves the quality enough you might want to consider buying one, because the colours of monitors tend to fluctuate over time (especially if you have an older CRT monitor).

Next to that you can buy a 'set' for your printer. You make a print of a file which you send to the vendor. He will, in return, send you a colour-profile. This colour-profile is not only printer-specific, but is also dependant on the paper (and printerink/toner) you use. So for every new kind you'll need a new profile.

I hope I've shed some light on the subject of calibration and all you professionals out there feel free to rectify any mistakes I've made ;-)

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