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The CIECAM02 color-appearance model enjoys popularity in scientific research and industrial applications since it was recommended by the CIE in 2002. However, it has been found that computational failures can occur in certain cases such as during the image processing of cross-media color reproduction applications. Some proposals have been developed to repair the CIECAM02 model. However, all the proposals developed have the same structure as the original CIECAM02 model and solve the problems concerned at the expense of losing accuracy of predicted visual data compared with the original model. In this article, the structure of the CIECAM02 model is changed and the color and luminance adaptations to the illuminant are completed in the same space rather than in two different spaces, as in the original CIECAM02 model. It has been found that the new model (named CAM16) not only overcomes the previous problems, but also the performance in predicting the visual results is as good as if not better than that of the original CIECAM02 model. Furthermore the new CAM16 model is simpler than the original CIECAM02 model. In addition, if considering only chromatic adaptation, a new transformation, CAT16, is proposed to replace the previous CAT02 transformation. Finally, the new CAM16-UCS uniform color space is proposed to replace the previous CAM02-UCS space. A new complete solution for color-appearance prediction and color-difference evaluation can now be offered. [ABSTRACT FROM AUTHOR]

Brill [Color Res Appl 2006;31:142-145] and Brill and Süsstrunk [Color Res Appl 2008;33:424-426] found that CIECAM02 has the yellow-blue and purple problems and gave partial solutions to them. In this article we model the optimum solution to the yellow-blue and purple problems simultaneously as a constrained non-linear optimization problem. An optimum solution resulting in a new CAT02 matrix is numerically obtained. This new matrix satisfies the nesting rule and performs better than the Hunt-Pointer-Estévez (HPE) matrix in predicting both corresponding colours and colour appearance data sets. Specifically, it was found that the new and HPE matrices performed significantly different on nine (out of 21) corresponding colour data sets and on all corresponding colours data sets as a whole. © 2014 Wiley Periodicals, Inc. Col Res Appl, 40, 491-503, 2015 [ABSTRACT FROM AUTHOR]

Here, we investigated the CAT02 and HPE triangles in both x,y and u′, v′ spaces. It was found that in u′, v′ space, the HPE triangle is separated into two regions by the line 3u′ − 8v′ + 6 = 0, which is the u′, v′ image of X + Y + Z = 0 under the mapping from ( X, Y, Z) to ( u′, v′). One of these two regions admits all-positive R,G,B triplets and the other all-negative R,G,B triplets, under the case of ( X + Y + Z) > 0. The findings of this study explained the computation problems of CAT02 and provided methods for solving the Yellow-Blue and Purple problems simultaneously. © 2013 Wiley Periodicals, Inc. Col Res Appl, 40, 30-39, 2015 [ABSTRACT FROM AUTHOR]

CIECAM02 has been used to predict colour appearance under a wide range of viewing conditions, to provide a uniform colour space, and to provide a profile connection space for colour management. However, some problems have been identified with CIECAM02. CIE Technical Committee 8-11 is currently working on the methods to resolve the problems for practical applications. Part of the CIE TC8-11 work is to repair the lightness computational failure. This article incorporates most of the previous suggestions and makes some further tests. It is hoped that this article will aid the ongoing work of the CIE TC8-11 and perhaps be the starting point for repairing the CIECAM02 for colour management and for the new recommendation. © 2012 Wiley Periodicals, Inc. Col Res Appl, 39, 143-153, 2014 [ABSTRACT FROM AUTHOR]

It has been reported that for certain colour samples, the chromatic adaptation transform CAT02 imbedded in the CIECAM02 colour appearance model predicts corresponding colours with negative tristimulus values (TSVs), which can cause problems in certain applications. To overcome this problem, a mathematical approach is proposed for modifying CAT02. This approach combines a non-negativity constraint for the TSVs of corresponding colours with the minimization of the colour differences between those values for the corresponding colours obtained by visual observations and the TSVs of the corresponding colours predicted by the model, which is a constrained non-linear optimization problem. By solving the non-linear optimization problem, a new matrix is found. The performance of the CAT02 transform with various matrices including the original CAT02 matrix, and the new matrix are tested using visual datasets and the optimum colours. Test results show that the CAT02 with the new matrix predicted corresponding colours without negative TSVs for all optimum colours and the colour matching functions of the two CIE standard observers under the test illuminants considered. However, the accuracy with the new matrix for predicting the visual data is approximately 1 CIELAB colour difference unit worse compared with the original CAT02. This indicates that accuracy has to be sacrificed to achieve the non-negativity constraint for the TSVs of the corresponding colours. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2011 [ABSTRACT FROM AUTHOR]