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CMYK Issues

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Redcap
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Can anybody explain or give me links to resources explaining clearly why a document has to be CMYK for printing purposes. The reason I ask, is every time my document is CMYK it comes out looking like crap, but if it it RGB it looks great when printed (note I have a CMYK laser jet printer)...

If I design a document all in RGB and then convert it to CMYK will it look odd, because right now I love working in RGB because it gives me more stunning prototypes, but I also want to start dabbling in professional prototypes and the like, but am afraid to start working in CMYK.

Also one last question... I know some people who take pictures in RGB but then they print them in magazines, games, etc, and the print looks great. I am assuming they converted it to CMYK, but how did they keep such high colour fidelity.

Just a few questions...

truekid games
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RGB is a monitor color scheme

RGB is a monitor color scheme (meaning it mixes red, green, and blue to make its colors). CMYK is an ink color scheme- your printer cartridge (or the offset printer at the printing company) has reservoirs of cyan, magenta, yellow, and black (key) which it mixes to make colors- that's why it needs to be CMYK for a printing company, so that their machine knows which reservoirs to draw the ink from.

when you print to your cmyk home printer, it's doing some sort of conversion to reach its mixtures. i'm sure most major printing companies can help you with conversion for their press (and some want very very specific conversion/file types, like quark-packaged files, etc.- which pretty much requires their help).

Gameprinter could probably give you a better answer.

VeritasGames
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The basics of the difference

The basics of the difference have already been described. What hasn't been said entirely is that there is not a 1-to-1 correlation between every color in RGB and in CMYK. When you have a color that doesn't translate 100% the printing software will make a best guess. If it does that too often your final image can look color-shifted or muddy.

While your home inkjet is CMYK an offset printing press can use very different technology. Printing on an offset press can look different from your home computer and even from other printing presses. Printing presses are, in part, mechanical, and so they have to be calibrated to adjust the color to specific tolerances. If you are working with a publishing house that has in-house graphic designers (like a magazine with its own printing press) then the original photos may be color adjusted so that they print out well on the printing press. Even with one home inkjet I owned, I noted that if I adjusted the bright to +10% and the contrast by +5% then the image would come out closer to what I want. It was sort of a standard color correction for my specific printer. While offset presses are pretty complicated, the operator may have to make certain parallel custom adjustments to get his press to function as desired.

If you go with a printer who doesn't bother with color adjustments he may just print the file you sent him "as is" and you get what you get. Since CMYK can be printed by layering four different inks on top of each other, I believe that it's possible to get precise color adjustments if the image is "color separated" or provided to the printer as four separate image plates. You could, for example, then tweak the cyan plate a little to color adjust it.

With professional offset runs of any significant size they'll usually offer you a printed proof, to allow you to reject the print run, modify things on your end, or ask for modifications on the printer's end. This can be problematic if you use a print shop that proofs on a different press or printing system than the final press. This happened to us. I had an image that was designed in RGB and printed in CMYK on my home printer. Looked great. The proof print sent to me was done on a digital press. It was almost a perfect color match. The final print run was done on a completely different press and my blues color-shifted into the purple range. We were on a deadline so we were stuck with the result.

Newer versions of Adobe Photoshop allow you to layout in CMYK mode. This is not a "what you see is what you get" mode, since your screen is still in RGB, but there's less color shift from press to press when you design totally in CMYK mode, because you won't have to worry about different color translation software platforms shifting the colors differently on different presses.

The best way to guarantee color is to get a CMYK swatch book. It'll come on a specific substrate. It's worth noting that the appearance of a color really can change depending on the type of substrate it's printed on. It can look more vibrant, duller, deeper, flatter, etc. So, ideally you want to see color swatches printed on the type of substrate you'll be using for your final product. Then, you pick a set of common colors that you are going to use in your design. You go into your page layout software (that can design in CMYK and not RGB) and setup those swatches. Then when your printer prints those colors on a matching substrate it will look very similar to the original swatches if all goes well.

You can get an idea of how your image might print by going into your image editing software and saving the image as a CMYK image and then re-opening it. Your screen is still RGB so you won't see the true differences, but you may get some idea about the directions of the color shift. Try also printing the RGB image on your inkjet and then converting the image the CMYK and printing it on your inkjet. There you'll see the difference between your image editing software's RGB-to-CMYK conversion versus your operating system and printing software's RGB-to-CMYK conversion. These won't give you exact parallels with what you'll expect from offset, but it may give you an idea of the range of possible results.

If you can, design using the swatch system I described in a page layout or image editing software capable of CMYK layout. Short of getting a printed proof from your printer and discussing things with him, that's gonna give you the most reliable results.

Lee

larienna
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I also have problem with

I also have problem with CMYK. I am currently using corel draw, I have found some color management options. In one of the option, all the color gets more dull than what they are actually printed. For example, the red are burned oranges, some yellows are light green and some colors are just more grayish.

If I change my color management, now it's the opposite. All the colors becomes more colorful, but some colors like brown becomes red.

Now I already printed a piece before and the resulting color is in between the 2 color settings described above. So the only solution I found so far is to put as much colors and components on a page, make some print test and hope I get the right color.

I have put so much hours in the graphic design so far, it is just annoying to work without knowing how it will go out on the printer.

I mean is it that complicated to do a color manager that works. I understand the differences between RGB and CMYK. I know that some colors does not print from one model to another. But why does the color manager does not only change these colors to show them on screen. Why does it have to change all the colors?

Also, there is some open source color management plug in that I don't remember the name. The only thing it does it take an image and split it in 4 different color channel (CMYK). But the problem is, what do you want me to do with that. What I need is a printable PDF, I don't need 4 seperate file. So I find this totally useless.

truekid games
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i've had that- blues to

i've had that- blues to purples, yellows to sickened greenish tint, etc. upping the picture resolution to 600 or 1200 and using brighter settings/lighter colors helps, but if anyone's got better tips, i'd be happy to hear them too.

gameprinter
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CMYK Issues

I think this has already been explained in more depth than I can offer, but the upshot is that printers need CMYK and that there are (as you've found) real differences in CMYK vs. RGB. For the most part, the differences aren't that dramatic. In your case, it sounds like it is - lucky you!

We (and most other printers) can convert from RGB to CMYK in prepress, but you run the risk that the results aren't to your liking. That could result in expensive changes to your art. We charge about $75/hour to do that sort of thing.

Your best bet might be to find a Pantone chip set and use that to find the CMYK colors you want. Also keep in mind that under the best of circumstances, the color fidelity on a home laser printer is not the greatest. For that matter, neither are most monitors unless they've been color matched. You can buy a USB gizmo that does that.

VeritasGames
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Delta E

Two of us have now mentioned the importance of color chip sets or color sample books. Again, as I noted, you really need to see the color on the appropriate substrate to see what you are going to get in the end. For instance the same color can look quite different on an uncoated stock as compared to a coated stock, and can look different again once a press coat is applied to the finished product.

I will add one additional point of note. In printing there is a measurement called a Delta E (the difference between two colors). If you care about the uniformity of a print job (say matching a print job to a proof or producing an expansion matched to an original product) then ideally you should research the topic of Delta E measurements and include a low, but reasonable one, in your contract with the printer. Lower end print houses may have never heard of it or may be incapable of measuring it. The limit of the difference you are willing to accept and the accuracy with which a print house can reliably hit a specific color exactly is called the Delta E tolerance. Leave that out of your contract and you can encounter some problems. I have found substantial Delta E shift within a single print run. Consider just a standard laser printer or self-inking hand stamp. If you go on too long the later impressions will be much lighter than the first one as ink/toner runs low. If your print house doesn't monitor the print run or has any problems with their printing equipment then you can get Delta E differences that are noticeable in a print run. Usually not on the same unique printed press sheet, but it can be substantial from different copies of the press sheet or on different press sheets. Games with expansions like CCGs can be harder to print due the desire for matching backs. I often buy games from smaller companies in the industry and can tell the difference between an expansion card and an original set card if I look.

larienna
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I am aiming for Print and play

Thanks for the info. I made some print test on cardboard and the color were much more darker than I tought. They were even darker than the black and white version.

I am aiming for print and play, So I need colors that will print relatively well on all printers.

Is there some general rules that I should follow to make sure it output well on any kind of printer and material: For example: does using lighter colors is better than using darker colors?

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