sRGB vs. CMYK Printing

[rhurley]

I worked on a brochure for a while using photos I took with my D200 set on sRGB and I post processed it using the same color profile. When I had it printed, the colors were off. Found out that Kinko's prints using CMYK. After a little reading it looks like most places print using this. My question is, what should I do with all my photos that I take in the future. Do I only need to worry about this at printing places like this. If I order a large poster of a photo I've edited in photoshop using sRGB, should I plan on it coming out with different colors. Do I need to convert the file to CMYK before submitting it?

Thanks

[jfrancho]

You need to get the profile from your CMYK printer, and soft proof, using Photoshop or some other color managed editor. RGB > CMYK conversions are a lot more complicated than RGB > other RGB color space conversions. Shadow areas can be real tricky.

[TLV]

Originally Posted by jfrancho

You need to get the profile from your CMYK printer, and soft proof, using Photoshop or some other color managed editor. RGB > CMYK conversions are a lot more complicated than RGB > other RGB color space conversions. Shadow areas can be real tricky.

Do you just ask your photo printer for the CYMK profile of his machine?

[jfrancho]

Yes.

[EOS_JD]

Most prepress print in CMYK. Take your images as you normally do and convert in Photoshop when required to do so.

If you are sending your images to a lab, they'll usually require sRGB.

I rarely print on prepress so all my images are generally saved ar aRGB or sRGB (depending on what I'm doing with them). However if I need to print say a booklet and need to send to a printer, CMYK files would normally be requested.

[jfrancho]

If you are going to press using a printer that requires CMYK, the conversion is not as simple as just Image > Mode > CMYK, though technically that will satisfy the printers requirements. You'll have to do some soft proofing using the profile supplied by that printer if you want the image to appear the same as it is on your screen.

[littlome]

The RGB > CMYK conversion is done by the RIP at Kinko's. I'm not clear if you are asking if you should be converting images to CMYK before dropping them into a layout program (i.e., InDesign, Quark), but if you are, I would recommend against that. Keep the images in a wider gamut, you'll lose a lot of color space converting to CMYK. The modern RIP's normally do a very good job at the RGB > CMYK conversions.

You hadn't mentioned whether your monitor or proofing device(s) is color managed. If they aren't, it's very hard to know which (if either) is showing you the colors accurately. I recommend that you consider some sort of monitor and output color management solution. X-Rite has a very effective solution (Eye-One), but it can be very pricey.

I just purchased a used X-Rite Pulse Elite used on eBay and it has done wonders for my workflow -- best $350 that I've spent recently -- it creates accurate profiles SO QUICKLY (scans a line of patches at a time, about 5 minutes to scan the printed targets and to create the profiles. There are lower-end color management solutions out there, but I've only had very limited success with them (Profile Prism, MonacoColor). PrintFix Pro is supposedly pretty good, but I've read reviews on either side of satisfactory for them. I went with the Pulse -- the reviews uniformly had high recommendations.

Assuming that the Kinko's equipment is properly calibrated and profiled, once your monitor and proofing system is profiled and color managed, what you see on the screen should have a very good semblance to the proofs that you're printing and with the output from Kinko's (assuming in-gamut colors). For out-of-gamut colors, the rendering intent deals with that issue. Perceptual or Relative Colorimetric are good rendering intents to start with.

[TLV]

Ok now I am going to sound dumb but printing is not my forte and the guys here is SA that know what's going on are few and far between. So to save me doing loads of research:

1. Is all printing done in CMYK - even the mass producing photograph machines? i.e. you may give the printer the shot in sRGB etc but they will always print in CMYK?

2. If this is correct then it must make sense to do the CMYK conversion yourself to have control of what colours are out of gamut? Providing of course you have the cmyk profile of the printer you are eventually going to use? And of course assuming that your screen is calibrated well.

Am I missing anything here?

Thanks

Derek

[karls-images]

OK now i'm a little confused with all these profile options, but what is the purpose of 'soft proofing' and a straight forward print..??

[jfrancho]

A print is what you get from a printer. Soft proofing is an attempt to, produce on screen, a preview of a specific device's output, like a printer.

[littlome]

Originally Posted by TLV

Ok now I am going to sound dumb but printing is not my forte and the guys here is SA that know what's going on are few and far between. So to save me doing loads of research:

1. Is all printing done in CMYK - even the mass producing photograph machines? i.e. you may give the printer the shot in sRGB etc but they will always print in CMYK?

2. If this is correct then it must make sense to do the CMYK conversion yourself to have control of what colours are out of gamut? Providing of course you have the cmyk profile of the printer you are eventually going to use? And of course assuming that your screen is calibrated well.

Am I missing anything here?

Thanks

Derek

Good question Derek. Here are my thoughts on this subject:

(1) You can already soft-proof out-of-gamut colors using Photoshop

View > Gamut warning

(2) The RGB > CMYK conversion process is complex

Just take a look at the Photoshop Color Settings dialog. Select Custom CMYK.

As jfrancho alluded to, there are a lot of considerations for manually converting to CMYK (max ink density, black generation, dot gain, etc.) which are hardware-specific, meaning that settings that work well for one manufacturer (i.e., Canon) may not work well for another (i.e., Ricoh).

(3) Manufacturers have invested $$$ in RGB > CMYK technologies

The RIPs (dedicated "computers" that drive the output devices) are engineered to handle the RGB > CMKY conversions using carefully tooled lookup tables (LUT) -- which by the way the manufacturers have invested a lot of $$$ to produce -- and usually do an excellent job. And you benefit from any improvements that are made to the LUT (via RIP firmware updates, assuming the service providers maintain their equipment regularly).

It is unlikely that you'd be able to do a better jobs converting to CMYK than what the manufacturers have done.

(4) You'd be working outside of the print shop's (i.e., Kinko's) comfort zone

Should you need help nailing the proper settings at a Kinko's / Staples /other print service, they're unlikely to be able to help you if you are working outside of their normal and established RGB workflow (unless, of course, they happen to have a print production expert on staff).

(5) Not all proofing devices can handle CMKY

There are also considerations for proofing on your local print device (inkjet, laser). Many color proofing devices (the software device driver to be specific) expect RGB and won't work with other color spaces without a software RIP. So unless you don't mind making lots of round-trips to the print service provider producing proofs on the final output device, check to ensure that your inkjet / laser can handle the CMKY color space.

(6 ) Doing CMYK conversion up front doesn't guarantee color accuracy

I just got off the phone with one of my customer's lead digital color guy (he prints to high-end Canon / Xerox digital color devices). He is having lots of trouble matching color when jobs come in CMYK, but no problems when they come in RGB. Could have something to do with limitations of color toner (Cyan and Magenta are particularly "impure"), or possibly the RIP software has been highly optimized for RGB workflow and not CMYK, or even a RIP software bug. Right now he's trying to convince his client TO STICK TO RGB, NOT CMYK color space.

--

I think in the end what most people are looking for is predictable color and not necessarily color accuracy. We (humans) have an excellent innate ability to sense DIFFERENCES in color, and have a poor ability to sense ABSOLUTE color. With that understanding, using the Perceptual rendering intent (which may shift colors slightly to "fit" the colors into the more limited print device color gamut but maintains the color spatial relationship) typically gives a very good result. When colors are more critical, using Relative or Absolute Colorimetric may give better results.

If color accuracy is major objective, partnering with a company who has advanced color knowledge and provides color printing services may be a way to go.

For those who are looking for predictable color, you can achieve reasonable success through soft-proofing and hard-proofing on color-managed devices with the understanding that these devices have a different gamut than the final print device. As previously mentioned, Photoshop allows you to preview the document in CMYK while in RGB.

Out-of-gamut colors are commonly handled in one of several ways:

* Stay away from certain colors (graphic designers are well aware of this), i.e., gold, deeply saturated colors such as fire-hydrant reds, intense violets, bright blues, etc.

* Choose a rendering intent (perceptual, relative colorimetric, absolute colorimetric, etc.) that more closely matches your goals for handling out-of-gamut colors. This is typically selected at the time of printing from the print options / preferences dialog. You may want to check with your local print provider to see whether they give you the ability to specify the rendering intent.

(There's no guarantee that the person running your job will set the rendering intent unless they are careful, this setting is typically buried deep within the device settings.)

Converting images to CMYK is "old school". The color-managed RGB way is the "new school". Publishing companies have been doing color-managed RGB for years and are getting excellent results (see Planet PDF - Hearst Magazines Adopt Adobe's Publishing Platform ).

[RichardGeorge]

Just a note: Adobe RGB is recommended when preparing documents for print, because Adobe RGB’s gamut includes some printable colors (cyans and blues in particular) that can't be displayed using sRGB. Adobe RGB is also a good choice when working with images from professional-level digital cameras, because most of these cameras use Adobe RGB as their default color space.(PS help)
We were having problems printing proofs on Xerox/Epson inkjet etc. Solved all problems by working in Adobe RGB - Viewing work while working in photoshop in: / view / proof setup / working cmyk - this allowed us a quick and accurate comversion to cmyk. The rip on the machine at Kinko's should give you a fairly accurate output from adobe rgb to cmyk if your photos are adjusted by viewing cmyk proof. Do not convert to cmyk unless you are outputing the image for offset printing and having film or direct to plate printing done.(I'm talking about offset printing using ink.) Watch the setting for dot gain. This is a function for adjusting how large the dots are being reproduced in the film for offset printing. When paper is going through an offset printing press it is squeezed and the dots of ink are either spread by pressure or bleed in the paper covering a larger area and creating a color shift. Selecting dot gain actually removes color to make the output dot smaller. CMYK settings are usually device driven. JFrancho gave the best advice - get the profile from the printer. And make sure your monitor is calibrated.

[EOS_JD]

Originally Posted by TLV

1. Is all printing done in CMYK - even the mass producing photograph machines? i.e. you may give the printer the shot in sRGB etc but they will always print in CMYK?

2. If this is correct then it must make sense to do the CMYK conversion yourself to have control of what colours are out of gamut? Providing of course you have the cmyk profile of the printer you are eventually going to use? And of course assuming that your screen is calibrated well.

1. Not all printing is done in CMYK. Look at modern inkjets with up to around 10 inks!! All prepress printing is done in CMK though. That is industry standard.

If however you send your images to a photo lab, although they may use the CMYK colours to print the images, the RIP will do a better job than you can do when it converts the images to print. Many inkjet printers prefer RGB because they convert to CMYK on the fly. The manufacturer builds in the appropriate specifications to get the best possible results. If you intercede by setting up the CMYK yourself, your results will suffer.

2. So it does not always make sense to convert to CMYK unless you are advised to do so by your lab/printer. My mate is a press printer and he's done a few jobs for me and I've had to convert my images. It's not too difficult but he advises it's better to convert at the start of the process (before editing) if you can.

[TLV]

Originally Posted by EOS_JD

1. Not all printing is done in CMYK. Look at modern inkjets with up to around 10 inks!! All prepress printing is done in CMK though. That is industry standard.

If however you send your images to a photo lab, although they may use the CMYK colours to print the images, the RIP will do a better job than you can do when it converts the images to print. Many inkjet printers prefer RGB because they convert to CMYK on the fly. The manufacturer builds in the appropriate specifications to get the best possible results. If you intercede by setting up the CMYK yourself, your results will suffer.

2. So it does not always make sense to convert to CMYK unless you are advised to do so by your lab/printer. My mate is a press printer and he's done a few jobs for me and I've had to convert my images. It's not too difficult but he advises it's better to convert at the start of the process (before editing) if you can.

OK - so why is it that when I take my pics to my local photolab in AdobeRGB and process them through his Frontier machine to 8 x12 prints they all come out desaturated. Then he says but the colours are out of gamut!....and shows me in PS the gamut warning. You are saying that his conversion is not calibrated correctly? Help please I must solve this to remain sane.

[littlome]

Any chance you could post a file so we might analyze it?

[TLV]

Originally Posted by littlome

Any chance you could post a file so we might analyze it?

Post or send to you...the pic I am talking about is under the thread "Tonie at Sunrise" under Fashion.....but just tell me what you need and i will send it to you with pleasure

Thanks for the interest

[jfrancho]

Originally Posted by TLV

OK - so why is it that when I take my pics to my local photolab in AdobeRGB and process them through his Frontier machine to 8 x12 prints they all come out desaturated. Then he says but the colours are out of gamut!....and shows me in PS the gamut warning. You are saying that his conversion is not calibrated correctly? Help please I must solve this to remain sane.

Probably because the machine is calibrated to accept sRGB embedded files. Convert them to sRGB, and your problem will disappear. Not sure what sending/posting would do. Ask your printer what colorspace the files should be in. If they don't know, find another printer.

[littlome]

Originally Posted by jfrancho

Probably because the machine is calibrated to accept sRGB embedded files. Convert them to sRGB, and your problem will disappear. Not sure what sending/posting would do. Ask your printer what colorspace the files should be in. If they don't know, find another printer.

I was looking to confirm the color space of the image to rule out problems with the image.

Your thoughts regarding the machine treating TLV's image as if it were already in sRGB color space sounds exactly right - makes perfect sense (light bulb goes on)!

[jfrancho]

Gotcha. What is most likely happening is that the Frontier machine is assigning the image sRGB, because that's what it expects irrespective of embedded color space. Assigning a color space is a HUGE no-no in color management. Never allow any device to assign a color space. Always convert! If the machine expects sRGB, then convert to sRGB before converting to 8 bits per channel and saving as a jpeg destined to print. Keep n mind, this a wholly separate issue from that posted by rhurley.

[Blinky]

There is lots of good info here and I'm not up to wading into it but one thing needs to be cleared up... if it's printed on white paper, it's printed CMYK, that is, subtractive color vs. RGB which is additive color.

It's true that modern RIPs are great at CMYK conversion but most magazines and offset printers prefer images which are already converted to CMYK in the layout file because the designer will have proofed them that way. You still have to proof after RIPping the pages but the image color/spot color matches will be more consistent when the whole layout file is in CMYK.

If you print to a Fuji Frontier or a Noritsu digital printer like at most mini-labs you can improve color matching by using one of Dry Creek's custom profiles... they have profiles for most digital outputs in the US. You can look up your preferred mini-lab in their database and download the profile. Otherwise go sRGB because like John says, that's what the printer expects as a default.

littlome has it right about consistent color being most important, dead on accuracy across the gamut is virtually impossible, ask anybody doing fine art reproduction. With that in mind, color management is an incredibly complex subject with relatively simple solutions. Get a system down by working with your printer and stick to it.

One last thing, save yourself some headaches and balance color by the numbers whenever possible, forget what it looks like on screen. Make sure your grays are gray and your whites are white and you'll be 90% there. Keep it sweet and simple and forget about perfection.

I don't mean to come off sounding like some big authority here, I'm not... but lemme tell ya, I'm bald and gray and most of that came from balancing color for print... that and a psychotic girlfriend anyway.