I Have a Printer, Now What?
The goal of any proof is to provide an faithful representation of the final printed piece. The printer software included with your printer invariably does not provide a means to compensate for any variations as the printer ages, materials change, or ambient conditions that affect color rendering. Most importantly the printer software has no mechanism to validate and confirm the color accuracy of the printer.
Achieving Accurate Color Through a RIP
- Color Calibration: The default printer driver included in your printer purchase is limited in many ways. One the biggest limitations is the lack of support for a color measurement device. A color measurement device is crucial to maintaining an optimal and consistent printing. A Raster Image Process (RIP) captures data from a spectrophotometer color measurement device to create compensation curves, commonly referred as linearization or calibration curves, not unlike Photoshop curves. These simple curves can help a lot in achieving consistent color. A more advanced implementation involves 4D correction like in the GMG ColorProof product.
- Postscript: There are several printer languages available to communicate with a printer. Usually a printer manufacturer creates drivers to work with OS default printer language. However, print service providers use Adobe Postscript language for their professional printing systems. To truly get a sense of how the images, graphics, and text will look you should use the same printing language. Almost all RIPs use Postscript level III or the new Adobe PDF print engine.
- SNAP | GRACoL | SWOP | FOGRA: Target print specifications are necessary so there is some predictability and tolerance of what is achievable on print. A good RIP will allow the calibration be adjusted and refined to be measurably be within an agreed tolerance. Again RIP software and color measurement device are required to ensure proofs are within industry agreed upon tolerance. Two common industry specifications for North America are SWOP and GRACoL. SWOP is usually assumed for CMYK files unless otherwise noted. GRACoL has been such a successful succession from SWOP defining good obtainable commercial printing in the US.
Color Matching in the Right Environment
It's important to note that color proofs and reference prints/samples are reviewed in an environment without a color bias from the room color, furniture, or lighting. Light Booths allow a correct environment for color evaluation to be obtained. International Standards Organization (ISO) 3664:2009 defines exactly what the surround environment and light quality needs to be evaluate color proofs. Deviation from the recommendations might impart a bias in your color evaluation that certainly won't be represented by the next viewer in a different location. The GATF RHEM Light Indicators are an easy way to confirm if a light source is indeed D50.