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  CMYK
HOME RAW CMYK COLOR MANAGEMENT IMAGES & VIDEOS HARDWARE SOFTWARE ABOUT

Discussing and viewing the CMYK images for that discussion on the web has serious drawbacks. Like all images CMYK and RGB, every deivce views images differently. Quite frankly it's impossible to view CMYK images properly on the internet as they are seen on a properly calibrated image correcting system or on paper and this is something we just have to deal with and one of the main reasons I don't do web tutorials. The other reason is that many individuals today just do not wish to invest the time into their personel skill set.

Below you see an RGB image one that I picked for our discussion because it is particularly difficult to convert to CMYK in a pleasing manner, you'll notice that the cut out flower heads in the RGB version and the CMYK versions below display a serious shift in color.

The issue that you have with CMYK images on a computer display and on paper is that almost always the image once printed will be more flat and dull then how the image displayed on screen, calibrated systems and proper CMYK image editors are better but not perfect.  

CMYK images on a display calibrated for color correction an viewed in a proper CMYK image editor will show the issues on the display much better than the internet browsers. For internet display you have to convert the CMYK image to RGB which in most cases does not affect how it displays on the diting system however once viewed through a web browser the RGB conversion of the CMYK image will clean up, it in many cases it will have more contrast and brightness therefore displaying on screen in a web browser far better than it will actually print.

There's much more to this RGB image shown below than immediately meets the eye. Many elements in the hanging banner are seriously out of the CMYK gamut and the shadow area in the lower right behind the plant converts very poorly. What you probably won't even notice is how when you scroll down to look at the two different conversions is that your eye will will naturally migrate to the one on the right.  The human eye prefers contrast and clarity, finding images like this appealing and the eye struggles with dark images, lacking contrast, finding them unappealing.

The drape that hangs over the end of the table is much brighter in the version on the right, the cut out flowers are also more bold on the right image and the overall image is brighter and more open.  The banner is more bold looking, the chalk board is more legible and the frame around the chalk board is more open and defined. The image on the right had to have RGB conversions done to it before converting to CMYK and a few color edits using masks after it was converted to CMYK. This work was done in about 10 minutes.

The wood grain in the version on the left is too dark, so much so that the detail is getting lost and the image is in general very flat. In fact with the changes we'll see when this is printed on paper the image on left would be rejected by my clients.

There is no way to correctly put a size 10 foot into a size 5 shoe and that's exactly what we're doing when we convert wide gamut RGB images into to CMYK .  There also are no correct conversions for a color that is out of gamut for its destination space.  However there are things to recognize as more pleasing and that's the key.

There is also the knowledge of how things will change on paper, and these things happen to all images and vectors when printed, more so for uncoated papers then coated papers and significantly more for news print or anything printed on pulp papers.

The image on the left will compress on paper and become even more flat looking than it looks now.  The one on the right has had the highlights opened as well as the mid and 3/4 tone so when it compresses on paper it will remain open in appearance but the print will add just a touch more contrast.

There are certianly differences between the 2 that show that there are compromises however the end user will see an open image that is clean and clear and pleasing to the eye.

Early binding verses late binding, (more on that subject below) in short early binding converts the RGB image to CMYK and then sends the file to be printed and late biding sends an RGB image and lets the printer convert.

The display of the version on the left is in fact not nearly as bad as what you'll see when this image is printed on paper if you use late binding.  Unless you demand and pay for hard proofs and color corrections which will delay the project and add cost.  The version on the right in print will have subtle changes but still will draw the readers eye and add value to the product it's printed in.

 
 
 

If you have an interest in practical CMYK conversion and theory, continue to read.

ALL devices apply a media profile at output. Like it or not a final color conversion from what you send to the output provider to their device WILL HAPPEN!

Early binding, (converting in the design to a designated color space before output) late binding, (converting to the destination space in the output device).  

Early binding for a trained user is in my opinion best for press work, it allows the user to choose how gray colors are transitioned in the image from white to black and to limit the total ink coverage to suit the paper that will be used for print. On the color management page click the link to down load the color management books and read them, once you understand the process you'll understand that gray balance on screen and in print is everything, once you achieve it all your colors turn out properly. 

What properly means is for the designer, PERCEPTUALLY PLEASING, not point for point accuracy as this does not exist in the RGB to CMYK conversion world!  Hard proofs are a very good idea.  This type of work once mastered also allows the user to demand a higher billing rate for their work.

Late binding I find can be better for output on many wide gamut digital devices specifically ink jet units and I use it regularly for these devices. I do this because the final media profiles are device proprietary and not usable in applications and these device media profiles many times provide a wider gamut than printing presses and in some cases may even be very close to sRGB or Adobe RGB.  Late binding can also be good if you demand hard copy proofs and are willing to pay for color corrections.  For quality work your price for work using late binding is unpredictable.  Without hard copy proofs and changes when needed your work will be unpredictable and in many cases substandard.

Driver based postscript and non postscript devices. 

Color critical work is very difficult and will not be possible with driver based non postscript devices. Ok output is the best you'll get.  For output to non-postscript devices all file content after you select print is rasterized to RGB. Non color managed non postscript processes all assume sRGB. Some devices allow the uses of specific source and destination profiles but they all suffer from the rasterization to an RGB space at the beginning.  The sRGB choice is limiting as many CMYK colors exist outside the sRGB color space.

Driver based postscript devices can have better color management but it still lags far behind digital front end processing. Driver based postscript devices do not suffer from the rasterization to RGB process at the beginning, they can rasterize to the native color space, some simply straight to CMYK, however they lack the sophistication in their color conversion processes of a RIP based digital front end.

 THE PROPER WAY for printing presses, in my opinion.

ALL (no matter where in the world you are) RIP based plate or film setters use an ink limit, linearization, dot gain curve that is applied to the final data that is imaged to the plate or film.

This, can in some cases can be an ICC profile, however in many cases it is not an ICC color profile but it does have a (TIC) total ink coverage limit which is key for the designer. It is used to linearize the press output and compress the input data to the ink limit of the press. So the reality is that there is always a final conversion but the process if handled properly is a minimal to zero compression. YOU'RE in control!

The RIP processing software has a base set of, RGB, grayscale and CMYK ICC profiles used as source and destination profiles for conversions of non CMYK data before being sent to the plate or film setter. This software also has specific look up tables to convert spot colors to CMYK.

HERE'S THE KEY PROCESS! Why early binding is better for presses. All CMYK data tagged with an ICC profile or untagged is handled as UNTAGGED, simply passing the CMYK color numbers along to the final data curve unaltered.

HERE'S the key for quality for the designer.  As long as you use in your application a CMYK profile that is equal to or less than the TIC of the press you CAN USE any CMYK profile you like, because the process simply passes CMYK number to the film or plate setter. Download my books from the color management page and you'll find instructions there to figure out what the true TIC is for each and every CMYK profile.

WHY do we want to do this? If you really want to know, use Photo-PAINT or some other image editor capable of displaying document color managed images, set the application to use the images embedded profile for viewing. Demonstrate this to yourself.  Pick a complicated wide gamut RGB image, save as and rename the file before each conversion and convert the same RGB image to US SWOP coated, ISO V2, GRACO 2006 and any other profile you want to test.

Now open each image allowing Photo-PAINT to view each image in its color space and view them simultaneously and you'll see the differences. Those differences are because of the profile TIC, BUT MAINLY because of how the profile handles gray balance. That gray balance process is what makes some CMYK profiles, look better than others. That gray balance is passed along through to the plate or film setter, so YOU CONTROL the look of your CMYK images. Late binding takes that control away from you.  

The PEAK of RIP based CMYK quality in my opinion.

I've been doing this since before the beginning of the digital technology.  In my experience 98% of all CMYK images require some color editing after CMYK conversion. You really have no choice if you want to demand quality in your output.

What that means is that those using late binding 98% of the time could have done better. How much better is the question? in my opinion 10% to 20% better for the average complex image. As images become more complex and the quality of the paper and print process increases that percentage changes to 100%.

What is a complex image and what is a quality output process? A quality output process is a coated paper #100 LB text US, 400 line AM screening or FM screened. A complex image has been demonstrated at the top of this page, in its RGB form it has many out of CMYK gamut colors.

A complex image may start as an RGB image from a carnival, having bright neon colors with prophoto gamut.  However most likely it will be like the image above a prophoto gamut image with multiple dark transitions in browns, greens, blues and grays.

These images are extremely difficult to reproduce in CMYK with a high degree of color definition, 100% of all these types of images will need manual conversion. You'll see these in high end country club brochures, architectural brochures and financial institutional work and in this case a brochure for a retail establishment.