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@loc.gov 202 707 8581