G7
Custom Printers is proud to be a G7 certified master printer. The G7 standard was developed to take into consideration advancements in technology and puts a higher importance on Lab color space (read more below) and gray values compared to SWOP, which emphasizes Density and Dot Gain. We are measuring color…. not ink thickness. What this means to our clients is a closer match from proof to press.
Technically speaking, G7 embraces a new specification known as GRACoL. ( General Requirements for Applications in Commercial Offset Lithography ) This essentially employs the use of process controls that were not available when the SWOP Specifications were established. Spectrophotometry was not yet a reality and plates were still created with film. The advances in technology have allowed the industry to use tighter tolerances when it comes to creating proofs, as well as measuring press sheets. We use ISO compliant inks throughout, as well as Lab values to more closely monitor our press to proof match. Gone are the days when ink density and dot gain are the primary objectives on a press run. These are still useful tools but we now employ gray balance for 3 color gray and black as the primary control for color. The G7 specification is valid across all platforms from Sheetfed, to Web, Digital and Inkjet.
We also offer Monitor calibration at your site so that what you see on your screen at the design stage… represents more accurately what comes off of our presses in the end. We have a Certified G7 Expert on hand to answer any questions you may have regarding this process and how it can help you bring your ideas to reality.
Advantages of Lab
Unlike the RGB andCMYK color models, Lab color is designed to approximate human vision. It aspires to perceptual uniformity, and its L component closely matches human perception of lightness. It can thus be used to make accurate color balance corrections by modifying output curves in the a and b components, or to adjust the lightness contrast using the L component. In RGB or CMYK spaces, which model the output of physical devices rather than human visual perception, these transformations can only be done with the help of appropriate blend models in the editing application.
Because Lab space is much larger than the gamut of computer displays, printers, or even human vision, a bitmap image represented as Lab requires more data per pixel to obtain the same precision as an RGB or CMYK bitmap. In the 1990s, when computer hardware and software was mostly limited to storing and manipulating 8 bit/channel bitmaps, converting an RGB image to Lab and back was a lossy operation. With 16 bit/channel support now common, this is no longer such a problem.
Additionally, many of the "colors" within Lab space fall outside the gamut of human vision, and are therefore purely imaginary; these "colors" cannot be reproduced in the physical world. Though color management software, such as that built in to image editing applications, will pick the closest in-gamut approximation, changing lightness, colorfulness, and sometimes hue in the process.
Benefits
- Color accuracy to original art
- Color predictability during file processing stage
- Color consistency from sheet to sheet
- Color repeatability on reprint orders
