Research On Color Image Watermark Algorithms

The digital watermark is regarded as the effective method to protect digital media information security, have caused people great interesting and notice in recent years . Because pictures spreading on the network are mostly color picture data, so this paper research digital watermark embedding and drawing algorithm in color picture by means of space , DCT and wavelet. We use powerful Matlab6.5 to examine algorithm unperceived and robust , which offer the algorithm that can be learned to the software and hardware digital watermark process system.This subject study the main content of color static picture of digital watermark algorithm as follows:1. Discuss the current situation of digital watermark and relevant concepts; Described the digital watermark appraisal theory and measure norm.2. Study the space color picture digital watermark algorithm.l)First, we pre-process the watermarking by means of Arnold; second, put the watermarking into the blue least significant bit(LSB). In the drawing process use the period to recover the watermarking.2)First use m-sequences expand frequence to modulate the two-value watermarking; second, put the watermarking into the blue LSB. Demodulate the signal in the drawing process.3. Study DCT land color picture digital watermark algorithm.1) First, we pre-process the watermarking by means of Arnold; second, transform the color picture from RGB space into YIQ space; third, carry, on dispersed cosine to change the luminance(Y), choose suitable coefficient to revise and imbed watermark information. In the drawing process use the period to recover the watermarking.2)As an effective watermark algorithm ,we must consider transparency and robust .That is how much watermark energy is embed into the picture. So the main problem is how to choose right signal intensity. The effective way of solving this problem is to utilize vision of the human eye shelter and use the adaptive watermark algorithm.4. Study wavelet land color picture digital watermark algorithm.1) First, transform the colored picture from RGB space into YIQ ;second wavelet luminance(Y); third expand frequence the two-value watermark ,in wavelet important coefficient imbed the watermarking.2) First, transform the color picture from RGB space into YIQ space;second wavelet luminance(Y), imbed the self-adaptation by the human vision characteristicThrough space , DCT and wavelet digital watermark, MATLAB artificial experimental indicate that the wavelet algorithm is the best in robust, which can effective to resist the attack such as JPEG compression , filter , noise pollution , sharp.