Stephen Marsh wrote:
Jeff Smith wrote in reply to Darrin Jenkins:
We've seen press proofs on three variations -
using traditional CMYK inks, standard screening at 175 line, hexachrome CMYK only with stochastic screening, and true hexachrome CMYKOG with stochastic screening. <<
HI Jeff, interesting stuff indeed!
So from the expected intended viewing distance for this work, how does the #175 and the stochastic compare - does the naked eye see any difference in dots or does it all just look contone? Does one look 'better' than the other, and if so in what ways?
The piece we're developing is a brochure - viewing distance is normal reading distance. Stochastic screening looks noticeably sharper for most types of images we're using. This isn't really a surprise. We've been using stochastic on a number of higher end catalogs for a sporting goods company over the past year and a half or so. Images with lots of detail really sing with stochastic. In the past, flesh tones and smooth gradients were problematic - taking on a mottled appearance in the worst cases. In fact, one customer pulled a project, and had the plates reimaged using traditional screening for this reason.
So, please do tell - what were the separation aimpoints for each of the three methods? Were the seps optimised for each condition or just a basic conversion to hex? Was the CMYK aimpoint specific or more general? Was the four colour HexCMYK ink job separated for standard four colour and run with hex process inks, or was this a custom sep taking into account the difference of the hex process inks? Then there is the true hex job as well...
I understand that you are not involved in the prepress so I might be asking too much here.
I can't speak to the specific aim points used for the separations, but the CMYK seps were produced to the same specs that we've refined over the past several years (this job has been printed by the same printing house for many years. That's why they've been willing to go the extra mile in finding a way to get a little closer on these difficult colrs.
The HexCMYK seps were optimized for the differences in the Hex colors, I believe. As for the true Hexachrome seps (CMYKOG) they were setup using a custom setup that the printer has been refining for a while on a continuing series of notecards produced for a very discriminating photographer.
We've found that we are needing to tweak the color here and there to get the separated files to match the actual color swatches of vinyl materials.
Adding orange and green should not dramatically add that much difference to the richness of blues, but I have no personal separation experience with hex seps and ink hue differences over regular process etc. Where blues/greens/reds are critical, spot colour bump plates are often made to mix into the CMYK.
We experimented with adding touchplates for the yellow and red flourescent colors to standard CMYK. The results were not particularly close to the actual colors, or as pleasing as the hexachrome. (color looked a little forced)
As you may expect, the most difficult part of this whole project has been proofing the work. The printer, with whom I've had an ongoing relationship of over twenty years, suggested press proofing. It is the first time in many years (over 15) that we've been able to work with press proofs, with the exception of packaging projects that were printed off shore.
I understand that Kodak is just releasing a true Hexachrome proofer - or at least a proofer capable of proofing hexachrome colors. We're waiting anxiously.
Hex or bump plate printing makes regular CMYK look like a reliable, consistent process that is a cake walk with no problems.
That's been our experience, so far.
Enter the wonderful
world of hex at your own risk, prepare for major problems but also prepare for a big smile if/when it all works as planned.
I'd add - enter it only with a printer/prepress service you trust, and with whom you've worked closely for a while, and who knows your expectations and whose capabilities you understand.
This is the ultimate learning experience.
I wouldn't go into it any other way. But We're hoping for that big smile...
-- Jeff Smith
Smith/Walker Design and Photography
P. O. Box 58630 Seattle, WA 98138 ph: 206-575-3233 fx: 206-575-3960
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