Number 197 - October 1999

Corner On Design - Color Calibration -
by Randall Rich May 1999 Sacra Blue, E-mail etype1a@jps.net
It is not enough to be a skilled operator of the hardware and software assigned to you, the computer operator. The machine and the program are your tools and you are expected to be able to maintain those tools in good working order. Simple troubleshooting skills are important in almost any skilled occupation, and especially so in the computer trades.     In the publishing industry, one area sure to give trouble is color. Contrary to popular belief, color cannot be matched, but only approximated. The reputation of a printing shop can hinge on how consistent and satisfactory its color output is.     One of our clients was featured in a national buff magazine, which extolled the virtues of the client's exclusive club. The client wished to produce a high-quality six-page brochure utilizing the magazine spread to encourage membership. To accomplish this aim, I scanned a number of full-color photographs which had been printed in the magazine at 122 lines per inch. I scanned the photos on an Agfa StudioStar scanner using FotoLook software which allowed me to descreen at the specified 122 lpi (lines per inch). In Photoshop, I applied a slight Gaussian blur to complete the descreening, then sharpened the scan. I routinely lighten the scan, using Photoshop's levels feature, and apply a small magenta color correction.     I sent the file through the Canon ColorPASS 4000+ Color Server with Fiery software (a raster image processor or RIP) to the Canon 700S Color Laser Copier, and was dismayed to see that the color was incorrect. In fact, the magenta tones were quite out of control, causing the sky to appear almost violet. Something was very wrong.	To begin, I checked the monitor's gamma settings and found these to be okay. Then I ran a test print on the Canon 700S color laser copier and found that the colors printed accurately. Therefore, the problem lay with the Agfa StudioStar scanner or the Canon ColorPASS 4000+. While checking the documentation for the Canon 700S color laser copier, I chanced to discover that the copier could also function as a scanner! I could get 400 dpi of full CMYK color output from the same device that I would be using to print! Furthermore, I could use this information to either eliminate or confirm the Agfa StudioStar scanner as the culprit of my inaccurate color problem.     The Canon functioned well as a scanner, but when I printed the resulting output, I had the same problem with too much magenta. So, the Agfa StudioStar scanner was not the problem. Obviously, the RIP had to be at fault. This $12,000 component sits between the CPU and the color laser printer and converts computer language into PostScript printer language. The RIP itself boasts 1052 MB (1 GB) of RAM and it needs every bit of it to describe the complex language of PostScript to a four-color printer.     Calibrating this baby was outside of my job description. I called the tech, and he reset the RIP to its original parameters. Evidently, the job is not that difficult, though I notice that it is not covered in the documentation that is supplied with the RIP. The technical support service promises to send a tech to show me just how it is done, since the procedure should be carried out periodically, depending upon temperature variation, rate of usage, vibration, and who knows what.     In any case, at last I had beautiful color output and I put together a mockup of the six-page brochure. The salesperson presented it to the client and if we make a sale, I will have a perfect piece to add to my portfolio.
Number 197 - October 1999