The histogram shape-based digital watermarking

which has the characteristics of low distortion

strong robustness

and etc

has become a hot topic in information hiding fields. Upon the basic properties of the existing histogram shape-based digital watermarking

a modified histogram shape-based 2Bin M-ary digital watermarking algorithm is designed firstly

and then

a concret ternary digital watermarking as an example of the M-ary system is further implemented. In the designed algorithm

the embedding threshold is adjusted according to the embedded watermark information capacity and the size of the carrier image. Under the condition of maintaining the high or low shape of the adjacent 2Bin histogram unchanged

the modified pixel number and the block strategy are determined to realize the embedding and extraction of watermark information. Experimental results show that this method is able to balance the relationship between image quality and watermark capacity intelligently

and that it greatly improves embedding capacity and image quality compared to these existing algorithms

meanwhile equips with the ability to resist the traditional geometric attacks and common image processing operations.