"by the way YCM stands for Yellow, Cyan and Magenta a special dye tranfer that yield the best film prints for restoration."
More specifically:
DYE TRANSFER
A NEW OPTIMISM
Mention “dye transfer” to most anyone in the publishing industry and they’ll tell you it’s obsolete. Ask commercial printers about it and they’ll declare it passé. Raise the subject with a group of fine-art photographers and printers—even Hollywood filmmakers—and you’re likely to get a different opinion.
At least that was the conclusion at an autumn weekend retreat in Vermont hosted by fine art photographer Luke Powell. Over 30 past and present dye printers and photographers from all over North America, Germany and Australia took Powell up on his invitation. A typical conversation-starter was, “Where were you when you heard…?” The question concerned Kodak’s abrupt decision in 1993 to pull the plug on the manufacture of dye transfer products, leaving some 500 photographers and technicians without a source of the materials they depended on for their livelihood.
That decision is still keenly felt among practitioners. The intensity of their response is remarkable, even more so considering the investment dye transfer requires—and not just in terms of money. The process, also known as dye imbibition, starts by creating tricolor separation negatives from a transparency. Exposing each negative onto a specially-coated film creates three bas-relief images called matrices, the degree of relief proportional to the exposure they receive. The matrices are soaked in complementary acidic dye baths and rolled in register onto special photographic paper secured to a pin-register board. The pH difference between the dye and the paper aids the transfer of the dye. It’s a painstaking process that takes years to master.
So why, in this age of instant gratification, would anyone cling to this technology? For one thing, it gives enormous control over color density and balance. And it yields an archival print of spectacular richness and longevity. Bob Pace, a respected authority on color print processes for two generations of photography professionals, is a fervent believer: “I have made over 25,000 dye transfer prints and nothing I have seen in all this time has shaken my feelings about this process.” And Kodak’s dye transfer guru Frank McLaughlin, who taught the process over the phone to generations of image-makers until his retirement in 1986, states simply, “The dye transfer product is the most manageable, most color-pure, most true-to-life photographic product ever invented.
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Dye transfer printers are elated at recent indications that Technicolor—the cinematic version of dye transfer—is returning to the big screen. The re-release of Giant in 1996, the first American-printed Technicolor feature film in 21 years, has heightened interest in its revival within the film industry.
Technicolor is also called IB printing (for “imbibition”, after the photographic term “dye imbibition”). Technicolor, Inc., ended IB printing in the U.S. in 1974. Technicolor London closed its operation in 1977, but not until they’d made five IB prints of Star Wars for George Lucas.
The restoration of the Star Wars trilogy brought IB printing back to the forefront. According to Leon Briggs, who worked with Lucasfilm on the restoration for over two years, the original negatives had faded only 5 - 15%, well within normal range. But he explained that George Lucas wanted the original color in the restored version. Lucasfilms technicians were able to accomplish this goal for Star Wars, but only because they had an IB print to use for color reference.
Yes......I am a geek. 
(Although I find the "color reference" to be a bit laughable, seeing as how much it helped in the final colors of the official DVD.) 
