Accurate reversible color-to-gray mapping algorithm without distortion conditions

• Published in: Pattern recognition letters Vol. 31; no. 15; pp. 2405 - 2414
• Main Authors: Horiuchi, Takahiko, Nohara, Fuminori, Tominaga, Shoji
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.11.2010; Elsevier
• Subjects: Applied sciences; Color embedding; Color-to-gray; Exact sciences and technology; Image hiding; Information, signal and communications theory; Miscellaneous; Reversible color mapping; Signal processing; Telecommunications and information theory; Color-to-gray; Reversible color mapping; Color embedding; Image hiding; Image texture; Subband decomposition; Mapping; Algorithm; Color image; Accuracy; Wavelet transformation; Signal processing; Haar transforms; Image transmission; Spatial resolution
• ISSN: 0167-8655; 1872-7344
• DOI: 10.1016/j.patrec.2010.07.014

This paper proposes an accurate reversible algorithm without any distortion conditions such as a print-san process for converting full color images to gray images while preserving the chroma and spatial resolution of the images. In our previous study, we proposed a reversible color-to-gray algorithm using a second-level Haar wavelet transform with a packet assignment technique. We have improved this algorithm by devising a color embedding technique. The proposed algorithm distributes color information effectively in the one-level wavelet subbands for preserving the chroma and spatial resolution. Experimental results show that the proposed algorithm can achieve a higher accuracy of recovering color images from the textured gray images of the original color images. We also present a practical application of the proposed algorithm to a color-hiding image transmission; this application permits color recovery only to a specific user with a key.