David Townend wrote: >> You need a >> separate calibrator module and a spectrophotometer to do your own >> linearization - or you need to find someone with the right toys to do it for >> you. > > Why is this ?
Essentially linearization is all about making sure the output you get is approximately the same as what you send to the machine. If you send a black 30% tint to the machine you want a black 30% tint out > When one is judging greyscale wedges/tiles in order to > ascertain the optimum printer setting before outputting a test target (to > then make a profile from) it is judged by eye ? Unless you have a densitometer or a spectrophotometer. > Why can't the same procedure > be applied when outputting via a RIP ? Essentially you need to linearize all inks (including light cyan, light Magenta and light black) which includes making sure that the amount of light colours are proportional to the dark inks. So suppose I want to print a 40% magenta tint, this needs a certain density of light ink and a certain density of dark ink. I'd hate to have to judge that by eye. Laso it will visually be very hard to tell a 90% Yellow from a 95% yellow. Most people would be unable to actually perform a satisfactory linearization by eye, which is why only a few RIP producers have bothered making a manual linearization. Epson Grey balancer (for use with 2100, 7600 etc. is an exception - sort of as it's for the RGB driver - Properly used it will give you slightly more accurate profiles though). When you evaluate a wedge as mentioned above prior to profiling you are looking for the paper setting with the optimum tonality for grey - not neutrality, and not for each individual colour. Obviously if you are able to linearize you printer prior to printing the patches you can get a better result, possibly with more black and cleaner blacks, better neutrality along the grey axis, and certainly a more straight gamut and a more predictable output. Profiling a linear device can yield accurate results with only about 80 patches. Profiling one with crossover curves here and there and a huge cast may require thousands and thousands of patches for accuracy - and most probably accuracy in this case will cost some posterization. There is an old saying (ok maybe not that old): You can never have enough gadgets or spend enough time on linearization. With sensible software, I tend to spend about 3 hours making a good linearization for a printer with ultrachrome inks on a single substrate. And it takes a LOT of printing, measuring, adjusting and printing, measuring adjusting etc... Best Regards Thomas Holm / Pixl ApS - Photographer & Colour Management Consultant - Adobe Certified Training Provider in Photoshop� - Apple Solutions Expert - Colour Management - Imacon Authorized Scanner Training Facility - Remote Profiling Service (Output ICC profiles) - Seminars speaker and tutor on CM and Digital Imaging etc. - Home Page: www.pixl.dk � Email: th[AT]pixl.dk -- =============================================================== GO TO http://www.prodig.org for ~ GUIDELINES ~ un/SUBSCRIBING ~ ITEMS for SALE
