After reviewing The Sappi Standard #5, I checked out the Sappi website and found another booklet entitled The Sappi Standard #2, Managing Color. I thought this would contain useful information, so I ordered the print book, and I wanted to share it with you.
Although the book addresses ways to extend the color gamut with touch plates, ink substitution, and hybrid 6-color printing, I think it’s most useful information pertains to controlling color from the monitor to the inkjet proofer or laser printer to the final offset printed copy.
Without color management, you will have no idea whether what you see on your monitor will match what you see on press. That’s scary, given the high cost of mistakes in custom printing. The goal, as the Sappi book notes, is to coordinate the color profiles (ways color is defined on each piece of equipment in the design and printing chain) and map these to each other and to an objective standard, so that a job printed anywhere in the world will match the same job printed anywhere else.
That is, not only should the soft proof on the designer’s computer monitor (rendered in the RGB color space) match the output of the commercial printing vendor’s inkjet proofing device, but the printer’s inkjet proofer should also be “fingerprinted” to his offset press. But color management should go even further. The printer’s press should be calibrated to an objective standard (such as G7). Presumably, all G7-certified print shops will come up with visually identical (in terms of perceptible color information) print products regardless of the press equipment they use.
The Sappi promotional print book, Standard #2, Managing Color, could easily be 500 pages of dense technical material. (The book is actually very short, but there’s that much information in this area of prepress.) That said, here are a few concepts to get you started in your own research into color management.
RGB vs CMYK
Images rendered on a monitor use red, green, and blue light to produce a given hue. In contrast, images produced on a laser printer, inkjet printer, or offset press employ the process colors (cyan, magenta, yellow, and black) to create a given color. Since the RGB color gamut is larger than the CMYK gamut (more reproducible colors), software must adjust “out-of-gamut” colors, mapping them to the next closest reproducible CMYK build when converting from the initial on-screen image to the file that your commercial printing supplier will print on his offset press. By doing this, the color mapping software must compress the color gamut (from the larger RGB color space to the smaller, press-ready CMYK color space).
Color Management
Color management software can measure, in numeric form, the perceived colors visible on a scanner, monitor, proofing device, or printer. This data file, called an ICC device profile, describes the behavior of color on that specific scanner, monitor, proofer, or press. These profiles can then be compared and adjusted to ensure consistency from one device to another.
What Is G7?
G7 is a standard, a protocol of sorts, that allows commercial printing suppliers across the world to match the output from their proofing and custom printing devices. According to the Sappi color management book, they do this by “defining the gray balance and neutral print density curves.” That is, they reference the cyan, magenta, yellow, and black halftone dot area used to produce a neutral gray color on a device.
It’s All Up to You
All of this becomes either very abstract or very scary. Eventually, you, the designer, must take responsibility for the color on your computer and monitor to ensure that the color you see will be the color you get in your final printed product.
The Sappi Standard #2, Managing Color gives you a list of what you need to do:
- Request your offset or digital printer’s ICC color profile. Your goal will be to match this offset or digital press characterization to your own system.
- Use off the shelf software and hardware to measure and characterize (or profile) the elements of your design system (particularly your monitor and inkjet printer).
- Do this every two weeks (or at least calibrate your monitor and inkjet printer once a month).
- Remember that monitors will change their ability to render colors as they age, and each device will have a different color profile (even monitors of the same make and model).
- Keep the area surrounding your design workstation visually neutral (gray or muted colors in the background) so as not to affect your perception of on-screen color.
- Remember that ambient light in your design studio, such as sunlight, will affect your perception of color as well as contrast.
- Paper weight and quality will affect color rendition. The more ink the paper can hold, the more faithful the color will be.
My Personal Advice
Color management is difficult to master. Personally, I’d always request a hard-copy proof for a color critical job. Make sure the proofing device is fingerprinted to the press (your commercial printing supplier will know what this means). You want to make sure your printer can match the proof you see to the final offset printed product.
If you don’t like the proof, just be happy that you caught the problem before your job went to press. Consider the cost of a proof an investment in the success of the job rather than an expense.
If the color on the proof is wrong (or the image has a color cast), adjust the original files, and then request another hard-copy proof. When the proof meets your standards, then and only then give your custom printing vendor the approval to go to press.
This entry was posted
on Monday, May 28th, 2012 at 9:04 pm and is filed under Offset Printing, Prepress, Printing, Proofing.
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