June 2015 - colorsync-users

dealing with printers
by Mike Stewart 04 Jul '15

04 Jul '15

Now that we are moving to Substrate Calculated Data sets based on paper white; how on earth do we communicate this to printers. Before OBA's we had GRACoL, Fogra47 - just to name a few. We would colour manage our proofs to GRACoL or Fogra47 (or some print specification), place an Idealliance colour bar on each proof and the customer/printer could measure the colour bar to see if we were in compliance or not to the particular specification. Now we start from GRACoL Uncoated 2013, change the Paper White values, create a new Data Set and proof to the new data set. Our colour bar on each proof now becomes useless as it will never match to the original GRACoL Uncoated 2013. How do we communicate this to a printer in Asia. How can they now trust our proofs. Do we give them a small single row Press Type Colour Bar that prints within the job itself and also give the printer the specs. for that colour bar. If so, what are the specs. of that colour bar (C,M,Y,K,R,G,B, grey balance swatches, etc). Data for that file would have to be colorimetric and not solid ink and dot gain values I'm guessing. Thanks Mike Stewart

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Fwd: dealing with printers
by Hanno Hoffstadt 18 Jun '15

18 Jun '15

I'd say that standard reference data still are the basis for substrate calculated data. The only extra information needed is the assumed substrate white (CIELAB). So my vision is to print that LAB along with the control strip of the proof, and anyone can check the proof control strip after entering these Lab numbers. One could even imagine that this user interaction is not needed: The paper white simulation which is measured could be compared against the standard, and if different enough, could directly be used to substrate-correct the aim values for the whole strip. Maybe informing the user that a custom white has been detected, OK to proceed? E.g. ISO 12647-2:2013 usually has a tolerance of 2 b* units for the PS (= printing substrate) categories, and explicitly states in the preamble that the standard can be applied to substrates outside if one uses a substrate correction method like the informative one given in Annex B and other standards. (A minor detail is the black XYZ needed in the formula, but this could be derived starting from the 100 K value given in the standard.) Hanno ------------------------------ Message: 3 Date: Wed, 17 Jun 2015 12:19:37 -0500 From: Mike Stewart <mstewart(a)embassygraphics.com<mailto:mstewart@embassygraphics.com>> To: colorsync-users <colorsync-users(a)lists.apple.com<mailto:colorsync-users@lists.apple.com>> Subject: dealing with printers Message-ID: <CAFB95os3sXyi6gH9+ZXKvJxUcnchKLpP8GfVE=dAHAi2spFySA(a)mail.gmail.com<mailto:CAFB95os3sXyi6gH9+ZXKvJxUcnchKLpP8GfVE=dAHAi2spFySA@mail.gmail.com>> Content-Type: text/plain; charset=UTF-8 Now that we are moving to Substrate Calculated Data sets based on paper white; how on earth do we communicate this to printers. Before OBA's we had GRACoL, Fogra47 - just to name a few. We would colour manage our proofs to GRACoL or Fogra47 (or some print specification), place an Idealliance colour bar on each proof and the customer/printer could measure the colour bar to see if we were in compliance or not to the particular specification. Now we start from GRACoL Uncoated 2013, change the Paper White values, create a new Data Set and proof to the new data set. Our colour bar on each proof now becomes useless as it will never match to the original GRACoL Uncoated 2013. How do we communicate this to a printer in Asia. How can they now trust our proofs. Do we give them a small single row Press Type Colour Bar that prints within the job itself and also give the printer the specs. for that colour bar. If so, what are the specs. of that colour bar (C,M,Y,K,R,G,B, grey balance swatches, etc). Data for that file would have to be colorimetric and not solid ink and dot gain values I'm guessing. Thanks Mike Stewart

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Re: OBA's yet again
by Hanno Hoffstadt 18 Jun '15

18 Jun '15

Chroma is maybe too general (it could put a yellowish, say b*=+9, and a standard uncoated paper accidentally in the same group :-) As a rule of thumb, assume +1 a* per -4..-5 b* for a neutral paper tint. (This can be approximated from the relationship between CIELAB and CIE whiteness and tint via CIEXYZ. It depends slightly on your chosen lightness level and uses different observers, but is good enough. L* does not change much.) So I'd rather use grouping in b* with a corresponding a* tolerance band (e.g. +/- 1.5 a* units). Typical ab* values would be along: 0.0 -2 (FOGRA39, FOGRA47), 1.5 -6 (FOGRA51 candidate), 2.5 -10 (FOGRA52 candidate); see FRED15 on www.eci.org A deviation of +/- 2 b* units is maybe just acceptable. So you could set one group center at a* 2.5 b* -10, the next one at a* 3.5 b* -14 (which is already quite bluish, high fluorescence. You probably won't need another one beyond that), a previous one at a* 1.5 b* -6 etc. Unless you have distinctly reddish (or greenish) papers, there is no need for groupings away from this tint-neutral axis (in plus or minus a* direction). For the L* grouping I would agree which Terry that less than 3 units (+/- 1.5) is not necessary/reasonable. Hanno > > ------------------------------ > > Message: 4 > Date: Wed, 17 Jun 2015 14:28:58 -0400 > From: Terence Wyse <wyseconsul(a)mac.com> > To: Mike Stewart <mstewart(a)embassygraphics.com> > Cc: "'colorsync-users?lists.apple.com' List" > <colorsync-users(a)lists.apple.com> > Subject: Re: OBA's yet again > Message-ID: <1159BC75-0691-4D34-A464-B92497226BF6(a)mac.com> > Content-Type: text/plain; charset=utf-8 > > I would probably use delta L* and delta Chroma as a metric for grouping. Since we know when dealing with OBAs, your delta chroma is going to increase from near-neutral to blue in hue (yellow papers would throw a wrench in this).In my experience, you’re going to see increasingly positive a* and increasingly negative b* values as OBAs increase. > > To keep it manageable, I would say deltas of 3 on L* and chroma for groupings would be reasonable. > > Terry > > >> On Jun 17, 2015, at 1:06 PM, Mike Stewart <mstewart(a)embassygraphics.com> wrote: >> >> As I've mentioned before. we are a pre-press provider for publishers and >> printers worldwide. We use an Indigo Press as a proofer and 95% of the time >> print/proof is on the actual press stock. This paper is mostly supplied to >> us by the printer themselves. As I look into our press room I would say >> that I probably have about 150 different papers; three quarters of which >> are uncoated stocks heavily laden with OBA's. Using the i1Pro2 in M1 mode I >> have measured all the papers. >> >> I cannot possibly have 150 different colour managed Hot Folders with >> individual colour tables based on each stock we proof on. (It would be a >> nightmare to build and control). I want to group papers into groups based >> on LAB M1 measurements. Example: 94, 1.0, -9 might be one group. My colour >> managed Hot Folder would have a colour set up created from 94, 1.0, -9 and >> I'm wondering if there are any "rule of thumb" tolerances I could use for >> my groups. Say Group 1 has been set up with 94, 1.0, -9 and my tolerance is >> L+/- 2, *a +/- 1, *b+/- 2. I could now group all papers that fall within >> those specs. I realize colour would not be an exact match for each sheet; >> but should be close enough to allow a printer to "match" the proof. >> >> Has anyone done this and does anyone know if my tolerances are out of >> whack? My +/- 2 could become quite a large tolerance if .. >> >> 94, 1.0, -9 >> 92, -1.0 -7 Is this to large of a gap? >> >> Any help would be appreciated. >> Mike Stewart

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OBA's yet again
by Mike Stewart 18 Jun '15

18 Jun '15

As I've mentioned before. we are a pre-press provider for publishers and printers worldwide. We use an Indigo Press as a proofer and 95% of the time print/proof is on the actual press stock. This paper is mostly supplied to us by the printer themselves. As I look into our press room I would say that I probably have about 150 different papers; three quarters of which are uncoated stocks heavily laden with OBA's. Using the i1Pro2 in M1 mode I have measured all the papers. I cannot possibly have 150 different colour managed Hot Folders with individual colour tables based on each stock we proof on. (It would be a nightmare to build and control). I want to group papers into groups based on LAB M1 measurements. Example: 94, 1.0, -9 might be one group. My colour managed Hot Folder would have a colour set up created from 94, 1.0, -9 and I'm wondering if there are any "rule of thumb" tolerances I could use for my groups. Say Group 1 has been set up with 94, 1.0, -9 and my tolerance is L+/- 2, *a +/- 1, *b+/- 2. I could now group all papers that fall within those specs. I realize colour would not be an exact match for each sheet; but should be close enough to allow a printer to "match" the proof. Has anyone done this and does anyone know if my tolerances are out of whack? My +/- 2 could become quite a large tolerance if .. 94, 1.0, -9 92, -1.0 -7 Is this to large of a gap? Any help would be appreciated. Mike Stewart

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Agfa Sublima screening
by Miller, Steve 17 Jun '15

17 Jun '15

Does anyone have experience with Agfa Sublima screening? My main question, what is the advantage, if any, when performing a G7 calibration? [Description: Description: Description: cid:F52454D3-70DB-47D5-9BD1-66B230BBC63A] STEVE MILLER Color Management Specialist BIC Graphic North America / 1000 3rd Ave. SW, Sleepy Eye, MN 56085 Tel: (1) 507 794 8203 Email: steve.miller(a)bicgraphic.com<mailto:steve.miller@bicgraphic.com> www.bicgraphic.com / www.norwood.com CONFIDENTIALITY NOTICE This electronic message is confidential and may contain legally privileged information intended only for the use of the individual or company named above. If the reader of this message is not the intended recipient, or the employee or agent responsible to deliver it to the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communications is strictly prohibited. If you have received this communication in error please immediately notify us by telephone and return the original message to us at the address above. ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please visit http://www.symanteccloud.com ______________________________________________________________________

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