Details:
Summary:
In the 2006 IPA (The Association of Graphic Solutions Providers) proofing roundup, a group of judges scored the degree of match between press sheets and the proofs printed to simulate these sheets. In addition, colorimetric measurements were made of test targets printed on those same press sheets and similarly printed proofs. This data, objective and subjective, provides an excellent opportunity to investigate the correlation between objective and subjective evaluations of images. The first step in evaluating the data was to check how well the judges agreed amongst themselves. Obviously if their agreement is poor, it is fruitless to even consider predicting the visual assessment. The delta E color differences were computed for each of the 1,617 patches in the test targets for each of the 22 proofing systems. Various techniques were used to distill these color differences down to a single objective quality number for each of the proofing systems, including standard descriptive statistics, averages of various collections of patches. Each of these various distillations of delta Eab values was then correlated against the judges' scorings.