RGB to CMYK

[amybest222]

In a Gracol G7 inviroment what is the best way to convert images?
Ive been having success with letting Acobat settings in Indesign (preserve numbers) and Gracol2006 ISO ... as my destination... does anybody have a way of getting bright RGB colors not to "mute in Photoshop" I really dont see anytbing wrong with this since the pdf before ripping in prinergy is CMYK..
Opinions appreciated... and suggestions !

Pinergy 4.2 APPE workflow thanks

 

[David Milisock]

RGB to CMYK

What do you mean by the gracol 7 environment? Do you mean letting the conversion happen during plating?

The best way for RGB to CMYK conversion depends on the destination and desired result.
I would in a gracol 7 destination environment use my image editor, with (on the MAC side) Adobe color engine perceptual rendering no BPC and convert to the gracol CMYK color space.

On the PC side (if complete MAC conversion compatibility was not an issue) I would use WCS color engine, perceptual rendering in my image editor and convert to gracol 7 destination.

 

[mattbeals]

Why on earth would you use use RelCol on Mac OS X and Perceptual and WCS/ICM on Windows? If you have the creative suite you use the same engine; Adobe CMM. I can't imagine why you would use different CMM's for the conversion when the Adobe CMM is available on both. They already are using PhotoShop/Acrobat/InDesign.

I generally have very good results using RelCol. Some images seem to separate "more pleasingly" with Perceptual.

The fact that the colors are muted I would wonder which RGB space the images are in, sRGB, Adobe RGB 1998, ECI, Nikon RGB, etc.

Are the monitors calibrated? Are they good monitors? How are they being viewed? How does the proof compare? A lot of questions to answer. Plus the simple fact that some colors are going to be out of gamut. So which colors are we talking about?

 

[drummerpaco]

Well, G7 Environment? I know when you convert to CMYK, you could assign the profile to GRACoL 2006.
When you convert RGB to CMYK, I would convert RGB - LAB - CMYK (and assign the profile regarding on what your proof or printing standards is). Then I would use Relative Colormetric instead of Perceptual.

If this shifts color space too much, then you need to modify each images separately to make similar color space as original RGB image.

 

[mattbeals]

When converting to CMYK you need to pick a CMYK to convert to. Whether it be a custom CMYK in the color management settings or an ICC profile. You do not convert to CMYK then tag with some other profile. There's no reason to convert an RGB image to LAB and then to some CMYK space. And then after that decide which rendering intent to use. Depending on the process you may be better off using perceptual. So convert to your destination profile. When you are in the convert color dialog box you can preview the conversion where you can switch profiles and rendering intents.

 

[Lukas Engqvist]

Can I just ask amybest222 what RGB you are using? And what do you mean by "mute"? If the "bright colours" are not within the gamut, then it is not photoshop muting, rather photoshop is showing what is reasonable to expect.
There are many variables unaccounted for. InDesign, Acrobat and Photoshop have the same colour management, if you have differing results then it is the configurations that vary. (Sounds like you are happy with the InDesign conversion but not the photoshop one.)

 

[David Milisock]

Why on earth would you use use RelCol on Mac OS X and Perceptual and WCS/ICM on Windows? If you have the creative suite you use the same engine; Adobe CMM. I can't imagine why you would use different CMM's for the conversion when the Adobe CMM is available on both. They already are using PhotoShop/Acrobat/InDesign.

I generally have very good results using RelCol. Some images seem to separate "more pleasingly" with Perceptual.

The fact that the colors are muted I would wonder which RGB space the images are in, sRGB, Adobe RGB 1998, ECI, Nikon RGB, etc.

Are the monitors calibrated? Are they good monitors? How are they being viewed? How does the proof compare? A lot of questions to answer. Plus the simple fact that some colors are going to be out of gamut. So which colors are we talking about?

>Why on earth would you use use RelCol on Mac OS X and Perceptual and WCS/ICM on Windows?
As mentioned in my post, you wouldn't for 100% cross platform compatibility however if that issue is moot, use what works the best.

Adobes color engine is, well Adobe, BPC is on by default and is not ICC compliant. Adobes color engine simply provides conversions that I, in some cases don't like. Specifically when using multiple color models as well as spot colors that need to be converted to sRGB. The problem with the MAC and Adobe is the lack of WCS support, with Canon (the largest supplier in the world of print and capture devices) and MS setting these as default engines Color Sync, Adobe, Kodak and LCMS (to name a few) are running an uphill race.

On the PC side with Vista and Windows 7 it's an interesting mix if you understand how the PC uses color engines. I prefer the color conversions (in a significant way) with WCS and if your work is mostly PC why use Adobe? Specifically if your applications of choice are not Adobe.

 

[mattbeals]

Well in this case it's pretty clear that Adobe apps are available and they are using the Adobe CMM. Further they are relatively happy with the conversion from RGB to CMYK and are looking to maximize, as much as possible with CMYK, the conversions using said tools. So whether they are on a Mac or a PC is really irrelevant. It comes down to which source profile(s), which destination profile and which rendering intent. I think it safe to assume that if they had other tools available and were able to follow some of what you were describing then they wouldn't really need to ask the question because they would have enough knowledge of color and color correction to solve this problem. Most likely using PhotoShop and the Adobe CMM to correct the issues. The OP has several outstanding questions to answer to be able to give the most germane advice.

 

[David Milisock]

Well in this case it's pretty clear that Adobe apps are available and they are using the Adobe CMM. Further they are relatively happy with the conversion from RGB to CMYK and are looking to maximize, as much as possible with CMYK, the conversions using said tools. So whether they are on a Mac or a PC is really irrelevant. It comes down to which source profile(s), which destination profile and which rendering intent. I think it safe to assume that if they had other tools available and were able to follow some of what you were describing then they wouldn't really need to ask the question because they would have enough knowledge of color and color correction to solve this problem. Most likely using PhotoShop and the Adobe CMM to correct the issues. The OP has several outstanding questions to answer to be able to give the most germane advice.

Agreed I wonder if they're doing conversions in the RIP or where? Too bad we do such a poor job in our schools with teaching the need to undersatand the base control technologies. So we're stuck with Adobe files in areas where they are just awful and then others not using Adobe where it's clear their technology has advantages.

Late binding, RIP conversions ad a lack of completion the required ambient working conditions controls are pretty much the reason why color is where it is today.