We have followed a new strategy of watermarking based on histogram specification. Our objective was first to extend the histogram specification method proposed by Coltuc to chromatic (2D) histogram and next to color (3D) histogram.This paper proposes a method to embed a watermark signal into a color image from the xy chromatic plane. The aims of this scheme are to resist to space deformation (e.g. rotation and scale change) and to cropping. We will explain firstly how the pattern used to modify the chromatic distribution of the image is defined and generated by a secret key, next how chromatic values belonging to the pattern are changed to insert watermark.To improve imperceptibility of watermark color distances corresponding to color changes are computed in the L*a*b* color space, so that we can evaluate the degradation of the image.Watermark detection is fast and blind, i.e. only the watermarked image and keys are needed, and not the original image. One part of this paper is devoted to 2D watermark patterns meanwhile the following part is devoted to 3D watermark patterns. Experiment done showed that our new watermark strategy is resistant against scale change or cropping and that 3D pattern improves the process.
Gaël Chareyron, Benoit Macq, Alain Tremeau, "Watermarking of color images based on segmentation of the xyz color space" in Proc. IS&T CGIV 2004 Second European Conf. on Colour in Graphics, Imaging, and Vision, 2004, pp 178 - 182, https://doi.org/10.2352/CGIV.2004.2.1.art00037