Improvements on the Embedding Method of Digital Watermarking in Still Color Images by Using Masking Effects

摘要

This note is a continuation of the previous result [7] of R. Takai and the second author K. Nagasaka. The total structure of image processing is identical with that in [7]. The above image processing makes use of the block correlation of DCT coefficients, instead of the Fourier transformation, as in [6] of Onishi and Matsui.rnThe main improvements of this note consist of the 98 possible embedding bits as digital watermarking for one cycle, and 4 times iterations are possible, so that the maximum possible embedding bits may reach to 392 bits. Usually, 392 bits for digital watermarking are not always necessary, hence we select 200 bits, say, according to the values of fluctuations, which signify the usage of the masking effects, [3], which is the second improvement. The last improvement is as follows. When we find the appearance of block noises after embedding digital watermarking, them we weaken digital watermarking to those embedded pixels according to the values of fluctuations.rnThese above three improvements result in keeping higher thernquality of still color images after embedding digitalrnwatermarks.