Visual Quality Improvement of Color-Embedded Gray Images for a Reversible Color-to-Gray Algorithm

In this paper, we propose a method to improve the visual quality of color-embedded gray images for a reversible color-to-gray algorithm. The reversible color-to-gray algorithm is an effective technique that considers several perspectives such as running cost, data quantity, and security in practical applications. Many reversible color-to-gray algorithms have been proposed, but most of these studies have only evaluated already-recovered color images. Although the visual quality of color-embedded gray images is also important, there has not been much assessment in this area. In this paper, we present a Fourier-based reversible color-to-gray algorithm to realize an improved visual quality of color-embedded gray images while maintaining the quality of the recovered color image. We also construct a color image recovery system from a printed gray image captured by a monochrome camera. Experimental results show that the proposed algorithm can improve the visual quality of both the color-embedded gray image and the recovered image in the closed-computer world, but the algorithm does not perform well for a printed gray images.