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Thread: EFI proof optimization white point settings

  1. #1
    PRC Member lessbones is on a distinguished road
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    EFI proof optimization white point settings

    I wonder if anyone has any experience with this-- I expect this is a bug that has been in EFI for a long time now.

    When running an optimization on a profile one is given 3 options for the paper white:

    absolute colorimetric: altering the paper white by laying down a flat tone under the print

    "suppress paper white": where efi claims "This setting applies the rendering intent Absolute colorimetric to the media profile but without paper white simulation in the proof"

    and finally "keep current paper white (no change): which is defined "With this setting, paper white is excluded from the optimization. However, the absolute colorimetric rendering intent is still applied."


    By simply reading the descriptions of the last two I could not understand the difference. The real problem however, is that no matter which option is chosen, the printer still lays down a solid tone under the image unless one switches the simulation profile rendering intent to Relative Colorimetric on EVERY iteration!

    I have a situation in which I am making SWOP proofs on a much cooler white paper, and I wish to have the paper white ignored or excluded. REALLY, I just want the simulation to be in Rel Col. In my testing I have had the best results selecting "suppress paper white" then switching to relative colorimetric for the sim profile on every round. However this is quite an arduous process and very prone to failure (on my part, in forgetting to switch) also It bothers me that these two extra options seem to have no effect on the appearance of the print-- I would think that at least one, if not both of them should NOT be simulating the paper white, yet both still seem to do so.

    I realize that it is not accurate to proof on a stock that has a very different white point, but my clients simply do not care for the most part, and it is extremely rare that we need to make verified proofs.

    Mostly I'm wondering if someone could more clearly define these two white point options, and maybe if anyone has any better ideas on how to do these optimizations (although with my current hack-method I get relatively accurate results, which would pass verification, except for the whites, but it still feels odd)

  2. #2
    Donor T. Schruda is on a distinguished road
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    hi lessbones.. just read your thread and i just recently had the following happening:

    i was using a DTP 70 for the profiling. and got anoid that the EFI charts are way big. an iti87.4 taking 3 A4 sheets which of course aren nested on a roll but printed under each other! great!

    so i decided to just build an own swatch with colorport where i can fit all 1617 patches on a 17inch roll 22cm wide...

    there i realized that already when building the profile.. first the deviceLink swatch is printed.. all good saying CM off on the print- but after that when i print my ICC swatch, it says - of course - CM active using the devicelink. but also on the print it says it is using some already existing paper profile... hmmm. ? hopefully just saying so

    but now to your point.. the paper around the swatch is tinted. !!

    afterwards i tried to use the original pdf chart and wasted those 3 pages.. THERE the paper stays unprinted..

    and with those i just built a profile and did 4 iterations surpressing white point.. and it never put down ink.. whitepoint stayed at dE 1.5

  3. #3
    PRC Member lessbones is on a distinguished road
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    Quote Originally Posted by T. Schruda View Post

    and with those i just built a profile and did 4 iterations surpressing white point.. and it never put down ink.. whitepoint stayed at dE 1.5
    THAT is interesting-- I have a feeling that all these issues are unsolved bugs--

    I used to have to manually switch the optimization 3cc by putting it into the "my profiles" folder from the "working" folder every time i ran an iteration.... maybe there just isn't any real science behind these flubs

  4. #4
    Donor T. Schruda is on a distinguished road
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    You know what also struck me..

    I did 5 iterations... And the last was supposingly the best. Avg .7 and max 5.. cuz in the dark saturated greens my profile didnt cover isocoated (wtf??).. anyway. When i loaded the .it8 of this iteration in the verifyer it should the same values avg and max like during iteration. Turned out yellow was off 4 tho. So i decided to use it2.. where yellow was said 2.6 and avg .8... Used this .3cc to print a test with fogra 2.2 wedge. Messured it.. and there! The yellow had 1.4.. ? I dout that my dtp70 is that unprecise... Maybe the printer? Or.. is is efi..

  5. #5
    Donor Apa_Cska is on a distinguished road
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    optimizations...

    Be very careful with optimizations! More than 2-3 steps cause rough posterization sometimes, always check with gradients!

    Ap

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