RGB or CMYK

[iskenderuna]

What profile should one give to graphics and images and indeed to a set of pages laid out in InDesign if one is going to print on a home printer (in this case CANON). I was under the impression that for all printing the CMYK is better...however I am wondering if CMYK is only to be used in professional printing and the good old RGB for home printers. Thanks for any advice
Iskender

[Bob_Levine]

For a home desk top inkjet printer, RGB is a far better choice.

Bob

[Jim_Oblak@adobeforums.com]

No printer prints RGB inks.

The reason why designers work in CMYK is because that is the mode that will be output. The issue is in the way the printer software converts color modes from screen RGB to print CMYK. Bob is correct in making the blanket statement that RGB is best for home low end printers but this is not always true. Try printing your work in RGB mode and also in CMYK mode. Compare both prints with what you expected from the screen display. Continue to print with the mode that seems most consistent with the screen display.

[Bob_Levine]

She can't print in CMYK because that option isn't availabe with
non-postscript printers.

While I usually agree with Jim, I'm going to argue this one. That
printer uses RGB data to print. By sending it CMYK data you're going to
force a conversion to RGB and then back to CMYK. That simply makes no
sense when you can start with RGB--which BTW is a much wider color
gamut--and avoid two conversions.

Bob

[Guy_Smiley@adobeforums.com]

Bob is correct on this one.

[Jim_Oblak@adobeforums.com]

ok - let's argue ;)

Are you arguing that I should not have suggested that the poster should try both ways to see which matches the screen display best? Are you arguing that I said that you were correct?

Yes, there are color mode conversions involved here. Not every printer behaves the same. This is why I suggested experimentation. Even if going from CMYK -> RGB -> CMYK may be a roundabout way, it might offer better results. The only thing to do is to try. There are plenty of variables here and one should experiment with a couple prints to see what works best.

Are we making a qualified statement that PostScript is the only printer language that supports CMYK color modes?

[Bob_Levine]

> ok - let's argue ;)

Oh, goodie. <g>

> Are you arguing that I should not have suggested that the poster should try both ways to see which matches the screen display best? Are you arguing that I said that you were correct?

Trying it both ways is fine, but IMO, a waste of time. The only way the
CMYK will match better is if everything is set up wrong.

> Are we making a qualified statement that PostScript is the only printer language that supports CMYK color modes?

Yes. You can't output CMYK data to a non postscript printer. The choice
isn't available in the print output. Composite RGB is the only choice.

Try it yourself and see.

Bob

[Jim_Oblak@adobeforums.com]

Are we talking about placing RGB vs CMYK images in InDesign or the option to print RGB vs CMYK in InDesign's print dialog? These are two different issues.

If iskenderuna was asking about choosing the option in the print dialog, then they must have a PostScript printer driver that supports both. iskenderuna would not have asked this question if they were already limited to RGB in the print dialog. This is why I suspected that this discussion was about the placed images or that iskenderuna was using a postscript home inkjet printer that allowed either color mode and prompted the question.

IMO a single test is not a waste of time if it well defines how you should do all future prints. This test would take less time than any argument. ;)

[Bob_Levine]

I'm talking about using RGB colors only in the document when the output
is going to a non-postscript printer.

If I didn't make that clear, I'm sorry.

Bob

[B_M@adobeforums.com]

Since the final output is going to be CMYK, regardless of how the printer & driver deliver the info, wouldn't it be prudent to use CMYK images in the document to delivery more accurate results?

Everyone knows there are going to be color shifts going from RGB to CMYK, most of the time they are unnoticable, sometimes drastic. If you work in CMYK the conversion to the printer to RGB should result in no change in colors since the RGB space is larger. Then the resulting conversion back to CMYK to actually image the file should be more consistent with the original CMYK.

Is that theory flawed?

Don't get me wrong. I usually scan my images RGB and keep them that way unless I know I will need CMYK separations. My home printer and my Indigo at work print fine that way but sometimes you can get strange results using RGB, especially in really dark areas.

Mike

[Bob_Levine]

But the final product isn't being printed CMYK. Read the original post.
It's being printed on a desktop inkjet.

Bob

[B_M@adobeforums.com]

.... which is a CMYK printer.

[Bob_Levine]

Not likely. I doubt very much it's postscript.

It's a printer that just happens to have cmyk inks. If it's not
postscript it uses RGB data to print.

Bob

[B_M@adobeforums.com]

You say "just happens to have cmyk inks." like there's any other kind of inkjet printer. Most, if not all, have CMYK inks, regardless of the color model the data is when sent to the printer.

So, if your data is CMYK to begin with it should more closely match the CMYK output of the printer. The change from CMYK to RGB should not result in any color changes; neither should the ensuing change from RGB data back to CMYK inks.

I'm more than willing to accept being wrong but if CMYK inks are coming out of the printer then it should be best to use CMYK images.

That's in theory, of course.

In reality the difference may be negligible but in some cases it could be worse than others.

Mike

[Bob_Levine]

Here's a quick rundown. With postscript, CMYK data is sent and used for
output. With non-postscript, RGB data is converted to CMYK by the print
driver. If you send CMYK data, first it's converted to RGB and then back
again.

Of course, that's a very simplified explanation but the bottom line is
that one color conversion is better than two.

Bob

[B_M@adobeforums.com]

Yes, I knew that. One conversion will always be quicker, not necessarily more accurate. But, then again the difference, in most cases, will be negiligible.

Mike

[Jim_Oblak@adobeforums.com]

wouldn't it be prudent to use CMYK images?...




Yes, it would be prudent so that you are not surprised when your vibrant photo of a rainbow on screen turns out to be mush on paper. If you want to be looking at consistent colors on screen, it makes sense to be viewing them in CMYK. There is no need to be looking at a vibrant RGB image onscreen and then be disappointed when it ends up as mushy CMYK ink on paper.

However, if you can stomach the change from what you see on screen to what gets printed, keeping your images in RGB mode saves file space and maintains a fuller spectrum of color if you want to use the image for purposes other than print.

We are debating the point at which RGB data becomes CMYK data. Does the conversion happen in InDesign? Does it happen in some unnamed RIP software? Does it happen in the printer driver? Does it happen in all of these? There are so many places where this conversion can occur that the best solution is to test output in a real world example. I've seen this go either way.

[B_M@adobeforums.com]

Yeah, I guess the best way might be to prepare the photo in CMYK mode and save the final version as RGB. Get the sure accuracy of the CMYK photo while only having to convert once.

[Jonathan_Balza@adobeforums.com]

OR... you could work in RGB, have all the advantages that offers you, including access to all filters, etc... and just turn on "Proof Colors". Then you don't have to convert any files that come in as RGB in the first place.

[B_M@adobeforums.com]

You could do that ... if editing in RGB were as easy as CMYK. If your editing is simply sharpening and simple stuff like that then sure. But color correcting a photograph is much easier in CMYK. I do it all the time in RGB but it's usually routine adjustments being done: unsharp mask, slight levels adjustment. But, some photos are stubborn and require CMYK to actually correct the colors.