Targeting a CMYK conversion for a specific printing condition can be as easy as opening Photoshop and selecting Image / Mode Convert to CMYK. Case closed and onto the next task. The problem is that creating a good CMYK conversion requires the understanding of where and how the file is going to be printed. Keep in mind that a CMYK value is not a colour but a recipe for a colour – and the colour you end up with greatly depends on the ingredients used.
Standards and specifications in the printing industry
Next month we're going to discuss how we can create a good CMYK conversion. But before we can do that, it's helpful to understand some of the known standards and specifications used in our industry. The most common term, SWOP, is considered a specification and not a standard in the formal sense. Other known specifications used in the print industry are GRACoL and SNAP.
In 1966, a graphics arts task force was formed by the Graphic Communications Association (now IDEAlliance) to develop a document containing general guidelines and recommendations that could be used as a reference source across the industry for quality color printing. Since that time, the GRACoL Committee has developed, maintained and published printing guidelines that have since become de facto standards in many pressrooms. The mission of GRACoL is to improve communications and education in the graphic arts by developing best practices that reflect the influence and impact of new technologies in the workflow of commercial offset lithography. GRACoL is a registered trademark of IDEAlliance. Learn more at http://www.gracol.org.
GRACoL has been busy conducting a series of press runs in both North America and England. They're working to develop an unambiguous description of how good commercial printing "appears" to the eye on a Number 1 sheet. The heart of this "print appearance" specification will be to develop a new, visually acceptable characterization data set to replace DTR004. The final press runs will form a body of work to be published as GRACoL 7. The primary goal of GRACoL 7 is to reduce as much as possible the basic appearance differences between different standardized processes, and thus simplify the preparation and exchange of printable files between them.
Imagine a world where you could actually predict how your file will print based on accurate ICC profiles. In our current situation, a large majority of images are targeted for SWOP even if they're being printed in a sheetfed press because it's the most widely accepted output/target choice.
Sheetfed Printing GRACoL (TR004): General Requirements for Applications in Commercial Offset Lithography
Additional Information: www.gracol.com
Web Offset SWOP (TR001): Specifications for Web Offset Publications
Additional Information: www.swop.org
Web Offset (Newsprint) SNAP: Specifications for Non Heatset Advertising Printing
Additional Information: www.gain.org
Printing across borders: While there are international printing standards in the form of ISO 12647 and related standards from ISO (International Organization for Standardization), they're not known or even implemented that well, at least in some regions.
So to address this issue, a gentleman called Olaf Dr¸mmer sent out an invitation for a meeting labeled "Printing across borders" to several hundred industry experts all over the world. Nearly fifty of these experts decided to join the meeting held on May 8th, 2005 in London.
The London meeting turned out to be a huge success, and all attendees agreed to join forces and get the necessary work and discussion started in order to achieve internationally recognized and implemented universal printing standards across all regions. For more information: www.backandforth.org
The obvious goal of creating accredited standards and printing specifications would be to have the ability to easily convert your RGB file to CMYK with a high degree of confidence that the print job was going to come fairly close to that matching your expectations. You could also set up accurate soft proofing on your calibrated monitor and go a step further and calibrate your inkjet proofer to match this new target. Ideally all proofing could work backwards from the press and not forwards from the designer, as it does today.