May 2011 - colorsync-users - lists.apple.com

A discussion on accurate color ...
by Wheeler, Barry 15 Jun '11

15 Jun '11

Hi - Sometime ago I asked for comments and suggestions as Michael Bennett (UConn Library) and I (Library of Congress) began working on a paper for the IS&T conference that was held last week. In reviewing some of the issues we have in obtaining accurate color as we image cultural heritage materials from our collections we decided to take direct measurements from our documents using a X-Rite 530 spectro. I got several comments from this group which were extremely helpful and now would like to share our results. Our initial expectation was to investigate if our color space specification (sRGB or occasionally AdobeRGB(98). Perhaps most frequently, unspecified RGB - all in TIFF master files, generally 8-bit although we now use 16-bit for exceptionally high value materials) was leading to inaccurate colors. We expect to take measurements from a sample of documents throughout the Library and then develop research questions for more detailed study. I have begun direct measurements, collecting Lab values generally. The measurements are so time-consuming that I only do full spectral readings on special request. So far I done 10 items from our general collection, 10 items from our Prints and Photographs collection, and 4 items from our Geography and Maps collection. The process is ongoing - I expect to finish maps and move onto our Music, Manuscripts, and Rare Books collections soon. So far we have over 700 readings of a wide variety of colors. Some initial results are interesting: 1. Of the 700+ readings, only 2 are outside the sRGB color gamut. Both of those are on coated paper on tipped in illustrations in a 1960's gem identification book. 2. Bright vivid colors of tropical birds, almost neon colors from posters, and even gold guilt are all within the sRGB gamut. 3. There are many subtle color variations within the central core of sRGB that curators are extremely interested in. Not just paper "white" but also colors of low saturation given the low reflectivity of the paper and inks in old books and documents. Using ColorThink, we overlaid the colors in the ColorChecker (original, large patch version with 18 colors and 6 step grayscale that we generally use to calibrate our cameras and the newer ColorChecker SG chart. 4. The colors of the cultural heritage materials are not very similar to the colors of the ColorChecker. 5. The more numerous colors of the ColorChecker SG are more similar and might provide a better calibration set. We have posted the following documents to the UConn repository. The complete paper: http://digitalcommons.uconn.edu/libr_pubs/37 The IS&T presentation: http://digitalcommons.uconn.edu/libr_pres/31 The current data: http://digitalcommons.uconn.edu/libr_pubs/35 The datasets will be updated as more document measurements are collected. Thanks, -Barry F. Barry Wheeler Digital Projects Coordinator Office of Strategic Initiatives The Library of Congress bwhe(a)loc.gov 202 707 8581

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RE: Color Wheels...'-}}
by tlabarbera 26 May '11

26 May '11

>>Roger Breton <graxx(a)videotron.ca>: Very nice. Very well put together -- kudo to Eizo. Thank's for posting this link. You're welcome...glad you found it interesting...I've not had a chance to more than browse through it rather quickly but I thought it looked well done also... Terrie http://tlbtlb.com/ tlbtlb(a)mail.com

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Color Wheels...'-}}
by tlabarbera 26 May '11

26 May '11

I thought everyone might find this pdf on color wheels of interest--url might wrap: http://www.eizo.com/global/products/library/resources/pdfs/EIZO_DCH_CH1.pdf Terrie http://tlbtlb.com/ tlbtlb(a)mail.com

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Mac OS 10.7
by Peter Harris 25 May '11

25 May '11

Has anyone on this list done any testing with color management on 10.7? Wondering what to expect. Peter Harris Staff Research Associate Programmer/Analyst Baskin Visual Arts Studios University of California Santa Cruz Santa Cruz, CA 95064 831-459-3107

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Re: A discussion on accurate color ...
by Mauro Boscarol 24 May '11

24 May '11

On 24 May 2011, at 19:51 , Eric Chan wrote: > boosting Exposure to +1, for example, means doubling the linear scene-referred values Exposure +1, what value exactly doubles? Perhaps L value of HSL (from RIMM)? Thank you. Mauro Boscarol

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Ideal gamma curve
by Roger Breton 23 May '11

23 May '11

If such thing does exist? But my question is more a question of implementation than what's best. I'm doing some programming of my own, having fun with my new colorimeter, and finally having the means of driving it to my heart's content from my computer. I am wondering what I should set its gamma response to, numerically? I don't have grand ambition (for the moment). I'd be happy just to set it along the lines of 2.2. I have measured my monitor "native" gamma curve, obtained from merely selecting 2.2 from the OSD gamma option. (Samsung 2693HM monitor). Excel file with the result is available here : http://cid-6ad0d45125f0fb40.office.live.com/browse.aspx/Shared?Bsrc=EMSHOO&B pub=SN.Notifications My question is how "low" do I actually let its luminance fall at the dark end of the "spectrum", sort of speak? I mean what should the black point be? I know there are important issues in physically mapping the black point, and that's why sRGB (I'm trying to find documentation) has a special treatment for the 0 to 32 ish RGB values range, in terms of luminance, for good visual reasons. There is also the issue of leaving black fall as dark as possible, to maximize dynamic range, but there is also the issue of selecting a black point that creates the most neutral blacks, at the expense of some dynamic range. The better monitor calibration package have that option... All help is appreciated. Let me know if you find my method of sharing documents conducive for you. Before you ask, this instrument is capable of good dark measurements. / Roger Breton

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Re: Barbieri LFP
by Dan Reid 23 May '11

23 May '11

Once you try one you may never go back….. Much, much, stronger light source than the DTP41T. No faulty/screwy measurements from patch recognition failing on the DTP41T. Polarizer filter (reflective). Someone finally listened to me…… 2.0, 6.0, 8.0mm aperture. Cake, pie, ice cream!!! Direct support by most RIPS (Onyx, GMG, Caldera, EFI) - today. Cons: ICC profiling can be not so fun in MonacoProfiler/ProfileMaker/iProfiler. Have to use clunky Barbierie (colorport) software to export data in CGATS. Not sexy, not fun, but doable. - Dan On May 19, 2011, at 5:03 AM, colorsync-users-request(a)lists.apple.com wrote: > From: Terence Wyse <wyseconsul(a)mac.com> > Date: May 18, 2011 2:20:53 PM MST > To: "'colorsync-users?lists.apple.com' List" <colorsync-users(a)lists.apple.com> > Subject: Re: Any comments or feedback on i!Publish? (Lou Dina) > > > > On May 18, 2011, at 3:43 PM, Roger Breton wrote: > >> Speaking of good instruments, anyone has anything good to say about the >> Barbieri LFP? > > I've heard that it's the tits for measuring backlit material....I'd love to try one some day. > > tw -- Dan Reid RPimaging, INC Color Communication Experts http://www.rpimaging.com | dreid(a)rpimaging.com Toll Free: (866) RGB-CMYK CONFIDENTIALITY NOTICE This message (including any attachments) contains information that may be confidential. Unless you are the intended recipient (or authorized to receive for the intended recipient), you may not read, print, retain, use, copy, distribute or disclose to anyone the message or any information contained in the message. If you have received the message in error, please advise the sender by reply e-mail, and destroy all copies of the original message (including any attachments.

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OT-Looking for production partners in Oakland/San Ramon area
by Barry Rudick 23 May '11

23 May '11

Off topic here. We are looking for production partners with color-managed workflow for printing on white Dibond panels up to 40x60 inches. This project will be up to hundreds of panels. Please contact me if anyone is interested. Cheers, Barry Rudick Houston, TX

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About Averaging
by Marc Levine 23 May '11

23 May '11

Ernst (et al), I wanted to point out a key point about averaging: it’s more about capturing variability in the print than in the instrument. If a printer was “perfect” you would really only need to collect 1 measurement per color patch. However, printers are not perfect. They make color by applying some kind of liquid, paste or powdered colorant, that is either shot out of a nozzle that is flying across a motorized rail, or is dribbled through a maze of rollers, or squeezed through a screen, or absorbed into a metal honeycomb and then transferred onto a plate, which is then transferred onto a substrate. Without even getting in either the variability related to curing, or the substrate consistency, speed, and transport alignment, you probably get the point that it’s not easy to print the same exact color twice, no matter what the technology (some more challenging than others). Even aqueous inkjet, which is now very mature and very repeatable, will demonstrate some variation. In my experience, variation is less likely to appear in adjacent dots of ink (where the same ink heads for the same inks are on or off). Variation is more noticeable when the inkjet heads need to stop, and then print again, somewhere else, on a different part of the media, or on a different piece of media. By printing/measuring/averaging 2 (or more) sheets, you are collecting data that better illustrates that variability of your process. Do you need absolutely need to average multiple samples? Of course not. Especially n the case of inkjet, the difference might be futile. That being said, for proofing at least, it’s all about the futile differences and averaging might get you an extra .1 or .15 dE. So, in response to your comment (reworded) "is the multi-sampling that instruments do a reasonable replacement for averaging multiple sheets?”.... I would say no. While it does help the instrument getter a better picture of the patch your measuring (and help it pick out one patch from another). Averaging multiple sheets is more about capturing the variation between that patch and the next time or place that it is printed. Marc On May 22, 2011, at 3:03 PM, colorsync-users-request(a)lists.apple.com wrote: > Send Colorsync-users mailing list submissions to > colorsync-users(a)lists.apple.com > > To subscribe or unsubscribe via the World Wide Web, visit > http://lists.apple.com/mailman/listinfo/colorsync-users > or, via email, send a message with subject or body 'help' to > colorsync-users-request(a)lists.apple.com > > You can reach the person managing the list at > colorsync-users-owner(a)lists.apple.com > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Colorsync-users digest..." > > > Today's Topics: > > 1. Re: iSis was Re: Any comments or feedback on i!Publish? (Lou > Dina) (Ernst Dinkla) > 2. Re: iSis was Re: Any comments or feedback on i!Publish? (Lou > Dina) (dpascale) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Sun, 22 May 2011 14:07:19 +0200 > From: Ernst Dinkla <info(a)pigment-print.com> > Subject: Re: iSis was Re: Any comments or feedback on i!Publish? (Lou > Dina) > To: "colorsync-users(a)lists.apple.com >> ColorSync Users Mailing List" > <colorsync-users(a)lists.apple.com> > Message-ID: <4DD8FC77.2010406(a)pigment-print.com> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > > On 05/18/2011 09:22 PM, Tyler Boley wrote: >> regarding the iSis, I'm finding with inkjet coated fine art papers, the >> usual suspects, that the rubber drive washers pick up (well dried) black >> ink from the black start bar and proceed to put it down in slight >> amounts on the lower color patches. With very light colors this clearly >> taints the result, with repeated measurement for averaging it's clearly >> seen, the later measurements differing from the 1st, progressively >> worse. Anyone find this problematic? I doubt my averaged data is more >> reliable than the first pass in the light patches. >> This leads me to my second question. If these instruments make multiple >> samples per patch and average them on the fly, other than some gross >> alignment error what is the point of multiple chart measurement for >> averaging if there has been significant averaging with one pass anyway? >> Tyler > > I thought that the HP Z spectrometer design was based on the iSis in > some aspects. In calibration just after printing the targets the Z > models will start with scanning the last printed patches first. So no > patch is touched by a pinch roller before being measured. The pinch > rollers of paper transport do not affect the print surface either but > when I observed that reversed scan order first I thought someone paid > attention to that aspect too. > > Averaging within one patch helps already but given the trend to increase > patch numbers and related to that smaller patch sizes I wonder whether > that is enough. It does not compensate on spectrometer temperature > deviations, not on differences in printing directions or paper texture > directions (HM Sugarcane), not on hysterises in spectrometers etc. In > strip readings the boundary detection takes its toll too. > > For quite simple custom greyscale targets to be measured on a HP Z3200, > 17 patches for linearising it, I made a descending and ascending range > twice. Large patches anyway on that machine and the spectrometer keeps > some distance from the patches. I wonder sometimes whether random > distribution of patches actually dampens spectrometer hysterises if > there is not extra check in the distribution of the patches on that issue. > A target print page + patch distribution that can be scanned in two > directions would be an improvement to reduce more effects. > > If more sampling is done it would be nice to throw the two most extreme > readings in the bin and average the remaining ones, more samples usually > increases the spread of the results too. > > -- > Met vriendelijke groeten, Ernst > > Try: http://tech.groups.yahoo.com/group/Wide_Inkjet_Printers/ > > | Dinkla Grafische Techniek | > | www.pigment-print.com | > | ( unvollendet ) | > > > > ------------------------------ > > Message: 2 > Date: Sun, 22 May 2011 11:35:34 -0400 > From: dpascale <dpascale(a)babelcolor.com> > Subject: Re: iSis was Re: Any comments or feedback on i!Publish? (Lou > Dina) > To: Ernst Dinkla <info(a)pigment-print.com>, > colorsync-users(a)lists.apple.com > Message-ID: <5054DCE3A5634391AFB6DE8FEE8FB7EA@noel2003> > Content-Type: text/plain; format=flowed; charset=iso-8859-1; > reply-type=response > > Hello Ernst, > >> If more sampling is done it would be nice to throw the two most extreme >> readings in the bin and average the remaining ones, more samples usually >> increases the spread of the results too. >> > > This is where a "weighted average", such as done in MeasureTool and > PatchTool, can help. > For at least 3 readings, and somewhere less than 20, a weighted average > first takes the standard average and then recomputes the average based on > each reading vs the standard average. The farther a reading is from the > average, the less it is considered in the average. The effect of "oddball" > readings is thus minimized. As you increase the number of readings, the > weighted average tends to be equal to the standard average. The effect is > most beneficial when doing averages on less than 10 series of measures. At > 15-20 readings there is usually no practical differences. In my view, > because of the time required to get all the data, an average made on between > 3 and 5 series of measurements is optimal. > > Danny > > www.babelcolor.com > > > ----- Original Message ----- > From: "Ernst Dinkla" <info(a)pigment-print.com> > To: <colorsync-users(a)lists.apple.com> > Sent: Sunday, May 22, 2011 8:07 AM > Subject: Re: iSis was Re: Any comments or feedback on i!Publish? (Lou Dina) > > >> >> On 05/18/2011 09:22 PM, Tyler Boley wrote: >>> regarding the iSis, I'm finding with inkjet coated fine art papers, the >>> usual suspects, that the rubber drive washers pick up (well dried) black >>> ink from the black start bar and proceed to put it down in slight >>> amounts on the lower color patches. With very light colors this clearly >>> taints the result, with repeated measurement for averaging it's clearly >>> seen, the later measurements differing from the 1st, progressively >>> worse. Anyone find this problematic? I doubt my averaged data is more >>> reliable than the first pass in the light patches. >>> This leads me to my second question. If these instruments make multiple >>> samples per patch and average them on the fly, other than some gross >>> alignment error what is the point of multiple chart measurement for >>> averaging if there has been significant averaging with one pass anyway? >>> Tyler >> >> I thought that the HP Z spectrometer design was based on the iSis in >> some aspects. In calibration just after printing the targets the Z >> models will start with scanning the last printed patches first. So no >> patch is touched by a pinch roller before being measured. The pinch >> rollers of paper transport do not affect the print surface either but >> when I observed that reversed scan order first I thought someone paid >> attention to that aspect too. >> >> Averaging within one patch helps already but given the trend to increase >> patch numbers and related to that smaller patch sizes I wonder whether >> that is enough. It does not compensate on spectrometer temperature >> deviations, not on differences in printing directions or paper texture >> directions (HM Sugarcane), not on hysterises in spectrometers etc. In >> strip readings the boundary detection takes its toll too. >> >> For quite simple custom greyscale targets to be measured on a HP Z3200, >> 17 patches for linearising it, I made a descending and ascending range >> twice. Large patches anyway on that machine and the spectrometer keeps >> some distance from the patches. I wonder sometimes whether random >> distribution of patches actually dampens spectrometer hysterises if >> there is not extra check in the distribution of the patches on that issue. >> A target print page + patch distribution that can be scanned in two >> directions would be an improvement to reduce more effects. >> >> If more sampling is done it would be nice to throw the two most extreme >> readings in the bin and average the remaining ones, more samples usually >> increases the spread of the results too. >> >> -- >> Met vriendelijke groeten, Ernst >> >> Try: http://tech.groups.yahoo.com/group/Wide_Inkjet_Printers/ >> >> | Dinkla Grafische Techniek | >> | www.pigment-print.com | >> | ( unvollendet ) | >> > > > > ------------------------------ > > _______________________________________________ > Colorsync-users mailing list > Colorsync-users(a)lists.apple.com > http://lists.apple.com/mailman/listinfo/colorsync-users > > End of Colorsync-users Digest, Vol 8, Issue 131 > ***********************************************

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Re: iSis was Re: Any comments or feedback on i!Publish? (Lou Dina)
by Ernst Dinkla 23 May '11

23 May '11

On 05/18/2011 09:22 PM, Tyler Boley wrote: > regarding the iSis, I'm finding with inkjet coated fine art papers, the > usual suspects, that the rubber drive washers pick up (well dried) black > ink from the black start bar and proceed to put it down in slight > amounts on the lower color patches. With very light colors this clearly > taints the result, with repeated measurement for averaging it's clearly > seen, the later measurements differing from the 1st, progressively > worse. Anyone find this problematic? I doubt my averaged data is more > reliable than the first pass in the light patches. > This leads me to my second question. If these instruments make multiple > samples per patch and average them on the fly, other than some gross > alignment error what is the point of multiple chart measurement for > averaging if there has been significant averaging with one pass anyway? > Tyler I thought that the HP Z spectrometer design was based on the iSis in some aspects. In calibration just after printing the targets the Z models will start with scanning the last printed patches first. So no patch is touched by a pinch roller before being measured. The pinch rollers of paper transport do not affect the print surface either but when I observed that reversed scan order first I thought someone paid attention to that aspect too. Averaging within one patch helps already but given the trend to increase patch numbers and related to that smaller patch sizes I wonder whether that is enough. It does not compensate on spectrometer temperature deviations, not on differences in printing directions or paper texture directions (HM Sugarcane), not on hysterises in spectrometers etc. In strip readings the boundary detection takes its toll too. For quite simple custom greyscale targets to be measured on a HP Z3200, 17 patches for linearising it, I made a descending and ascending range twice. Large patches anyway on that machine and the spectrometer keeps some distance from the patches. I wonder sometimes whether random distribution of patches actually dampens spectrometer hysterises if there is not extra check in the distribution of the patches on that issue. A target print page + patch distribution that can be scanned in two directions would be an improvement to reduce more effects. If more sampling is done it would be nice to throw the two most extreme readings in the bin and average the remaining ones, more samples usually increases the spread of the results too. -- Met vriendelijke groeten, Ernst Try: http://tech.groups.yahoo.com/group/Wide_Inkjet_Printers/ | Dinkla Grafische Techniek | | www.pigment-print.com | | ( unvollendet ) |

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