Semi-Invariant Reversible Mapping from Color to Gray

摘要

This paper proposes a reversible algorithm to convert color images to gray images while keeping chroma and spatial resolution. The original method of Braun and de Queiroz [Ret. 5] had theoretical problems such as deterioration in both chroma and spatial resolution. The authors describe a solution for these problems by devising a color embedding technique. A semi-invariant algorithm for chroma and spatial resolution can be realized by replacing a subband of the luminance component with the quantized high-pass luminance and chrominance signals. Experimental results show that the proposed algorithm can recover vivid color images from the textured gray images of the original color images, while keeping spatial resolution. Furthermore, the ability of color recovery from coded gray images is evaluated from the point of view of image coding using JPEG and JPEG2000.