June 2011 - colorsync-users

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: i1Profiler optimize from ColorPort data?
by Walker Blackwell 14 Jun '11

14 Jun '11

I was using CMRK as well. Were you using large color tables or medium? I was using16bit/large and optim. was throwing me an error and failing. May be an OS X 10.6 thing. I can file a bug report with xrite. Walker On Jun 14, 2011, at 1:01 PM, Terence Wyse wrote: > > On Jun 14, 2011, at 12:30 PM, Walker Blackwell wrote: > >> It doesn't allow optimization on 16bit/High Quality profiles. > > > Hmmm.....not sure if that's right...I've optimized a few profiles and I know that I always use 16bit "Optimize Quality" settings. Were these RGB or CMYK profiles? (I'm using CMYK profiles). > > Terry > > > > ______________________________________ > Terence Wyse, WyseConsul > Color Management Consulting > G7 Certified Expert > FIRST Level II Implementation Specialist > > > > > > Walker Blackwell 802.821.4451 www.walkerblackwell.com aim: greendirtblues

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i1Profiler optimize from ColorPort data?
by Walker Blackwell 14 Jun '11

14 Jun '11

Hey everyone. I got to try out i1Profiler a few days ago but my time was limited and I didn't get to test everything. As the software doesn't support DTP70s but does support exporting of cXF data and importing of CGATS I was wondering the following. If I build a patch set in i1P and import that data to ColorPort, print and read with a DTP70 and then export/import that data to i1P via CGATS, will i1P let me build out an optimization patch-set? I didn't validate this when I had my hands on the software. All the best, Walker Blackwell ps: I also found a few bugs in the software. It doesn't allow optimization on 16bit/High Quality profiles. But all in all, I thought the software was pretty freaking good. I built an optimized Eye One 1258 patch profile on top of a StudioPrint/SP9800 linearized environment and the neutral axis and color were superb.

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Mark Muse/HFC/NPS is out of the office.
by Mark_Muse＠nps.gov 11 Jun '11

11 Jun '11

I will be out of the office starting 06/10/2011 and will not return until 06/21/2011. I will respond to your message when I return. If this is urgent you may contact my supervisor Melissa Cronyn by email at melissa_cronyn(a)nps.gov for assistance.

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Good monitors in $400 - $500 Range
by Richard Booth 09 Jun '11

09 Jun '11

Our IT department needs to provide the art directors with some monitors to replace the mix of things they currently have (Imacs, Dells, old Cinemas). Their budget is in probably $500 tops, although something less than that would be welcome. I manage the prepress, where we have NEC 2490wuxis for color critical work. These are, of course, beyond their budget. They have asked me for recommendations. Is there something in that $400 - $500 price range with color uniformity, ability to set black level, contrast, brightness and RGB space independently? There is a fairly large range of work station environments (ambient lighting). I don't see them using calibration hardware or software. What is more likely is that I will help them get to their desired "look" (which will vary from one AD to the next) with the hardware controls on the monitors. Thanks -- Richard Booth Prepress Supervisor The Taunton Press 63 S. Main St. Newtown, CT 06470 203 304-3807 rbooth(a)taunton.com

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Accurate color follow up ...
by Wheeler, Barry 06 Jun '11

06 Jun '11

Hi - THANKS to those of you who have responded to my earlier message. I am interested in continuing the discussion directly with others who are interested. In particular, I am interested in exploring camera profiles and the set of colors used to improve the accurate of specific cameras. I must admit that I have not actaully done the math when I mentioned that the colors of the ColorChecker were not close to the colors commonly found in our documents. My immediate interest is in working with the Library and contractor staff who are directly involved in imaging our collection materials. So I simply import a color set (as Lab values) into ColorThink and display the colors, a gamut boundry, and the ColorChecker colors. Thus, by "distant" I am referring to the visual distance between color points in the ColorThink plots. I find this presentation is immediately comprehended - and usable! - by the staff. Unfortunately, almost any use of math and deltas tends to turn them off. The Library has an extremely large "production" conversion operation going. The Internet Archive currently has a ongoing "mass" conversion effort focused on materials from our general collection. They apparently operate on a "good enough" imaging model and considering they produce millions of images a year, the results are quite good and usable. Down the hill, the National Gallery of Art does almost "one-of-a-kind" imaging of their valuable artwork. We are in the middle. We still use scanners for large objects such as maps and posters, but most frequently we use PhaseOne P65+ backs and even two new Aptus II (80 mp) backs with production rates of a few dozen an hour from each camera. I am looking for a simple way to improve color accuracy without reducing production - or increasing costs! So I would like references, documentation, best practices, even hints and suggestions that will help me select color sets for profiling, determine what are reasonable expectations for improved color, and design experiments to test color sets against expectations. Thanks, -barry F. Barry Wheeler, Digital Projects Coordinator, Office of Strategic Initiatives, The Library of Congress Washington, DC 20540 bwhe(a)loc.gov 202 707 8581

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Re: / Re: Color management in web browsers
by Jacob Rus 02 Jun '11

02 Jun '11

Tom Lianza: >> Mark, that is not the reason the problem is not addressed. It was NEVER >> part of the Web specification, that is the reason it is not addressed. >> My own feeling is that color management “on the web” will not be handled by >> a browser, but by a web application. There are solutions to this, but they >> won’t be free. Jan-Peter Homann: > So far as I know, several W3C specifications reference, that untagged > data (images and graphic content) should be handled as sRGB in the > document to monitor chain. [...] > > In think, it is the most important task of the ICC today to develop > recommendations how the different levels of colormanagement should interact: > - application level > - OS level > - device level > > I will start also a task about this, at the internal ICC Graphic Arts > Special interest Group and give some feedback to the Colorsync > Mailinglist if something relevant happens there... Tom Lianza's statement is, as Jan-Peter says, incorrect. Both the CSS and SVG specifications address this question. In the "color" section of SVG, http://www.w3.org/TR/SVG/color.html > All SVG colors are specified in the sRGB color space [SRGB]. At a > minimum, SVG user agents shall conform to the color behavior > requirements specified in the color units section and the minimal > gamma correction rules defined in the CSS2 specification. In CSS, http://www.w3.org/TR/2008/REC-CSS2-20080411/syndata.html#color-units > All RGB colors are specified in the sRGB color space (see [SRGB]). > User agents may vary in the fidelity with which they represent these > colors, but using sRGB provides an unambiguous and objectively > measurable definition of what the color should be, which can be related > to international standards (see [COLORIMETRY]). Unfortunately, the HTML 5 canvas specification does not include any * * * I and others have been pressuring browser vendors to do proper color management of CSS colors for years now, without tremendous progress. Some useful links include: http://regex.info/blog/photo-tech/color-spaces-page3 http://www.webkit.org/blog/73/color-spaces/ https://bugzilla.mozilla.org/show_bug.cgi?id=16769 https://bugs.webkit.org/show_bug.cgi?id=9567 http://code.google.com/p/chromium/issues/detail?id=2602 My (possibly incorrect) recollection of the current state of browsers is: * Firefox has color management for CSS colors and untagged images (i.e. can assume they are sRGB), but it is turned off by default, leaving colors in the display's color space. I don’t know whether images tagged with a color profile are treated properly when that setting is off. They might be. * Safari has color management for images with embedded profiles, but not for untagged images or CSS/SVG/etc. colors. The excuse given in 2006 (!) was that because Adobe Flash colors were not color managed, other colors could not be either without causing a mismatch which would break the color coordination of web pages. * Chrome (inexcusably; one of the dozens of deal-breaker compatibility problems with that browser) does not support any kind of color management. * Opera also (and also inexcusably) does no color management. I don’t know what the story is for Internet Explorer, for Adobe Flash, or for mobile devices like Android phones or iPads, but I wouldn’t have high expectations for any of them. Essentially every browser currently violates the W3C specifications w/r/t color management, which is extremely frustrating for anyone who cares about both color and the web. Cheers, Jacob Rus

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