基于小波域数字水印的图像质量评价方法

Image Quality Assessment Based on Digital Watermarking in Wavelet Domain

为了进一步提高部分参考型图像质量评价方法的准确性和水印隐藏性,提出了一种基于小波域数字水印的图像质量评价方法.首先结合人类视觉系统的特性检测原始图像的纹理丰富区域,获得水印嵌入指示图;然后将原始图像进行3层小波分解,根据水印嵌入指示图,在每个小波系数块内嵌入自定义水印,运用量化参数自动调节系统确保数字水印的隐藏性;最后通过失真图像的水印复原率实现对图像的客观质量评价.与传统的图像客观质量评价方法(PSNR)和部分参考型图像质量评价方法(RRIQA)的对比实验表明,文中提出的方法在预测精确性上分别高出8.5%和4.4%,单调性上分别高出5.4%和2.2%,一致性上分别高出5.7%和3.4%.

In order to improve the precision and the watermarking invisibility of the reduced-reference image quality assessment method,a new image quality assessment method based on digital watermarking in wavelet domain is propsed.In this method,first,the texture-rich region of the original image is detected according to the characteristics of human visual system,and a watermark-embedded map is obtained.Next,a 3-level wavelet decomposition of the original image is performed.Then,a self-defined digital watermark is embedded in each wavelet coefficient block according to the watermark-embedded map,and the adaptive adjustments of quantization parameter are adopted to ensure the invisibility of watermark.Finally,the image quality is objectively assessed according to the watermark-recovering rate of the distortion image.Experimental results indicate that,as compared with the conventional image quality assessment method based on PSNR and with the reduced-reference image quality assessment（RRIQA） method,the precision,monotonicity and consistency of the proposed method are respectively 8.5% and 4.4%,5.4% and 2.2%,5.7% and 3.4% higher.