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The rise of RGB
September 11, 2007

For years, RGB has been treated as a pariah color space by most printers and prepress people. The expression was usually spoken of as a low-brow method for imaging, and not of the class that we elite printing professionals needed for our presses. Even today, Adobe InDesign will flag documents with embedded RGB images as having “errors.”

With the rise of electronic publishing, and publishing in multiple media – print on sheet-fed, print on newsprint, PDF, etc. – it has become more common to see documents created in RGB, and converted to CMYK only when going to press. This makes sense.

Digital cameras and scanners generate RGB files with a large color gamut. We use these digital color images in almost every document today, and should be taking advantage of the extraordinary color qualities of the images. And, as a larger number of documents are published electronically, we should be thinking in terms of leaving color in its original space for those documents that are made into PDF without first being converted into CMYK. Such documents look and print better on desktop printers than the same with images converted to CMYK.

There is another compelling reason for using RGB images in documents destined for print: converting to CMYK should be done with the specific press/paper/ink combination in mind. So, keeping color in its original space until the time of platesetting makes great sense. Then – and only then – choose an ICC profile that is fine-tuned to the printing parameters of the job.

Then, as is often the case, if the paper changes, or the job needs to be reprinted on another press, the only thing that need be changed is the output profile at the time of platesetting.

Many printers think that SWOP is an appropriate profile for sheet-fed printing (and Adobe sets SWOP as the default CMYK profile in its Creative Suite applications). It most definitely is not, and there are several much better profiles provided with the Creative Suite that are better-suited to sheet-fed printing. SWOP is a compromise for sheet-fed printers, and those who use it are short-changing their customers of some of the best color available on their presses (and in images printed thereon). When imaging plates for sheet-fed printing, it is much better to choose an appropriate sheet-fed profile that allows for the best qualities of sheet-fed printing to show.

Caveat coloro
But leaving the images in a publication in their original color space only works if the page layout person acknowledges the embedded profiles that are in most images today. All consumer digital cameras are factory-set to use the sRGB color space, while nicer cameras allow the photographer to change the color space to a larger gamut (like Adobe RGB 1998). When these digital cameras write images to the memory card, they automatically embed the profile into those images, establishing a color pedigree. If everyone who touches the images in the reproduction chain is respectful of the embedded profiles, then output to CMYK is certain to be better than any generic (usually wrong) conversion of color into CMYK.

Making device-specific PDF
Once a document is complete, the operator can make a PDF of it, applying the correct ICC profile as the PDF is generated. This makes it relatively easy to prepare files for print or electronic delivery with changes made in the output profile applied to the PDF. If a document is headed to the web for electronic delivery, then an RGB profile should be applied to the PDF; if the job is headed to a printing press, then the correct ICC profile for CMYK can be applied when creating the PDF.

Heresy?
Just about now, some printers shout “Heresy!” I promise – it’s a good idea to adopt an RGB work flow (where source images are provided in RGB color) and then deliver CMYK or RGB color finished work according to the output intent. This is the new era of document delivery, and we must be flexible to survive and prosper.

Posted by Brian Lawler on September 11, 2007 | Comments (0)