Geometrical methods for lightness adjustment in YCC color spaces

Ramin Samadani; Guo Li

doi:10.1117/12.640874

16 January 2006 Geometrical methods for lightness adjustment in YCC color spaces

Ramin Samadani, Guo Li

Proceedings Volume 6058, Color Imaging XI: Processing, Hardcopy, and Applications; 605809 (2006) https://doi.org/10.1117/12.640874
Event: Electronic Imaging 2006, 2006, San Jose, California, United States

Abstract

Lightening or darkening an image is a fundamental adjustment used to improve aesthetics or correct exposure. This paper describes new geometrical algorithms for lightness adjustment, implementing fast traversal of colors along lightness-saturation curves, applicable when the data starts naturally in YCC space (JPEG images or MPEG videos). Here, YCC refers generically to color spaces with one luminance and two color difference channels, including linear YCC spaces and CIELAB. Our first solution uses a class of curves that allows closed-form computation. Further assuming that saturation is a separable function of luminance and curve parameter simplifies the computations. This approach reduces clipping and better adjusts lightness together with saturation. Preliminary evaluation with 96 images finds good subjective results, and clipping is reduced to about 5% of a prior approach.

Citation Download Citation

Ramin Samadani and Guo Li "Geometrical methods for lightness adjustment in YCC color spaces", Proc. SPIE 6058, Color Imaging XI: Processing, Hardcopy, and Applications, 605809 (16 January 2006); https://doi.org/10.1117/12.640874

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