Research On Invertible Color-to-Grayscale Image Conversion Algorithm

Invertible color-to-grayscale image conversion is a new technology,and the basic idea of this technology is to convert a color image into a grayscale image with color information embedded inside such that we can reconstruct the color version,which is close to the original afterward.At present,there are many issues to be solved.Therefore,this paper researches invertible color-tograyscale conversion technology,and proposes two algorithms:(1)An invertible color-to-grayscale conversion algorithm based on revertible watermarking and clustering.We propose an efficient method by using K-means clustering to generate a color palette and its corresponding grayscale image,and further making use of a reversible watermarking technique to embed the color palette into the grayscale image.For the purpose of integrality authentication,the grayscale image is hashed as part of the embedded information before the embedding.In the process of reconstructing the color image,the color palette can be extracted correctly and the grayscale image can be recovered without any loss.Experimental results have shown that the proposed scheme with both clustering and reversible watermarking techniques can achieve better performance.(2)An invertible color-to-grayscale conversion algorithm based on lossy compression and highcapacity data hiding.The chromaticity and grayscale planes are orthogonal in the proposed method so that they can be processed efficiently without mutual influence.By using an efficient lossy compression operation,we can save the chromatic information as much as possible.By using two high-capacity data hiding techniques(reversible watermarking(RW)and least significant bit(LSB)substitution),we can embed the compressed chromatic information into the grayscale plane perfectly.Experimental results show that the best quality of reconstructed color images can be achieved by using RW,but the quality of the synthesized grayscale drops sharply.By LSB substitution,we can obtain high-quality synthesized grayscale and reconstructed color images simultaneously.Furthermore,we compared the proposed LSB-based scheme with several recently reported state-of-the-art methods and extensive experiments have validated the superiority of the proposed approach.The proposed algorithms have provided innovative invertible color-to-grayscale conversion ideas and dealt with some drawbacks of existing schemes.Extensive experiments have validated the effectiveness of the proposed algorithm.