Re: Colorsync-users Digest, Vol 5, Issue 209
Re: Colorsync-users Digest, Vol 5, Issue 209
- Subject: Re: Colorsync-users Digest, Vol 5, Issue 209
- From: Roger Breton <email@hidden>
- Date: Sun, 15 Jun 2008 19:09:50 -0400
Brian,
As amazing as it sounds, that's the sad truth.
I've personnally witnessed this very phenomenon on press.
Start with AM plates, run a number of sheets, adjust SID. Then stop. Change
over to FM plates, start again and observe how all ink keys must be closed
down, by a sizeable amount, in order to obtain the same color.
I mentioned this puzzling fact once on the G7 Expert list and was told that
this was a very well known fact in the industry. I was even given a link to
a GATF comparative study where this behavior is documented. I followed the
link through but I shied at purchasing the article in question :
> Stochastic Printing, Printability, and Runnability Compared to Conventional
> Screens [2004]
>
> Author: John Lind
>
> Subtitle: A Research and Technology Report
>
> Stochastic printing appeals to many printers these days, with some reports
> estimating that half of all printers have experimented with the technology.
> Some of the advantages touted for stochastic include greater rendition of
> detail, less sensitivity to changes in register, less sensitivity to increased
> inking, no moiré patterns, less ink consumption, and greater color gamut
> volume.
>
> This Research and Technology Report is the result of a study conducted for the
> 2004 Tech Alert Conference that sought to validate such claims by printers and
> vendors. Specifically this study examines ink consumption, documents the tonal
> calibration process, and looks for differences in blanket piling between
> conventional screens and one stochastic algorithm for coated and uncoated
> paper. The choice of test form used in the study allowed the comparison of the
> color gamut volumes for 133 lpi, 175 lpi, and 25-micron stochastic. Use the
> conditions, properties, and print run data reported here to help you
> investigate stochastic printing or benchmark conventional screening
> conditions.
>
> Contents: Introduction Stochastic Past and Present Stochastic Pros and
> Cons Sources of Stochastic Technology Methods and Materials The Test
> Form The Calibration Process Ink Consumption and Blanket Interactions
> Color Gamut Considerations The Economics of Using Less Ink Summary and
> Conclusions Acknowledgments References Appendix A. Project Protocol
> Appendix B. Calibration Data for Coated Paper Appendix C. Calibration Data
> for SCA Uncoated Paper Appendix D. Results for the Adjusted Curves and the
> Final Print Runs, Coated Paper Appendix E. Results of the Adjusted SCA Print
> Runs
Given your comments, I think I'll reconsider...
Best regards,
Roger Breton
>
> Regarding Roger's comments...
>
> Why would switching from AM to FM result in an ink savings?
>
> You're putting down the same dot area, and that would result in
> approximately the same amount of ink being put on the paper.
>
> The only thing that changes is the formation of the tonal information:
> a clump of machine spots vs. a pseudo-random distribution of the same
> machine spots.
>
> If you were to calculate the area of paper covered by ink per cell in
> an AM halftone and compare that the area covered by ink per cell with
> an FM screen, they should be the same, or very close, otherwise the
> image would be different.
>
> I am eager to hear the explanation.
>
> Best wishes,
>
> Brian P. Lawler
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