IW-SSIM: Information Content Weighted Structural Similarity Index for Image Quality Assessment

Zhou Wang


Information content weighted structural similarity measure (IW-SSIM) is an extension of the structural similarity (SSIM) index by incorporating the idea of information content weighted pooling. The same idea can also be applied to peak signal-to-noise ratio (PSNR), leading to an information content weighted PSNR (IW-PSNR). More information is provided in the following paper:

-          Zhou Wang and Qiang Li, "Information Content Weighting for Perceptual Image Quality Assessment," IEEE Transactions on Image Processing, vol. 20, no. 5, pp. 1185–1198, May 2011.


Source Code and Test Results

Five algorithms (PSNR, IW-PSNR, SSIM, MS-SSIM, and IW-SSIM) are tested with six publicly available subject-rated independent image databases (LIVE database, Cornell A57 database, IVC database, Toyama database, TID2008 database, and CSIQ database). In all databases, only the distorted images are included in our tests (reference images excluded). When the images are in RGB color, a Matlab function “rgb2gray” is used to convert the images to gray scale. The Matlab source code and test results (in Matlab .mat format) are provided here for future comparisons:

Model

Source Code

LIVE

Cornell-A57

IVC

Toyama

TID2008

CSIQ

PSNR

Code

Result

Result

Result

Result

Result

Result

IW-PSNR

Code

Result

Result

Result

Result

Result

Result

SSIM

Code

Result

Result

Result

Result

Result

Result

MS-SSIM

Code

Result

Result

Result

Result

Result

Result

IW-SSIM

Code

Result

Result

Result

Result

Result

Result

Our evaluations based on Spearman’s rank correlation coefficient (SRCC) and Kendall’s rank correlation coefficient (KRCC) are as follows. The “Average” values were computed as the direct average of 6 databases. The “Weighted-Average” computation takes into account the sizes of the 6 databases, i.e., a weighted average based on the number of images in each database (779, 54, 185, 168, 1700, and 866 for the 6 databases, respectively).

SRCC Results

Model

LIVE

Cornell-A57

IVC

Toyama

TID2008

CSIQ

Average

Weighted-Average

PSNR

0.8756

0.6189

0.6884

0.6132

0.5531

0.8058

0.6925

0.6887

IW-PSNR

0.9328

0.8759

0.8998

0.8475

0.6823

0.8311

0.8449

0.7896

SSIM

0.9479

0.8066

0.9018

0.8794

0.7749

0.8756

0.8644

0.8455

MS-SSIM

0.9513

0.8414

0.8980

0.8874

0.8542

0.9133

0.8909

0.8914

IW-SSIM

0.9567

0.8709

0.9125

0.9202

0.8559

0.9213

0.9063

0.8978

 

KRCC Results

 

Model

LIVE

Cornell-A57

IVC

Toyama

TID2008

CSIQ

Average

Weighted-Average

PSNR

0.6865

0.4309

0.5218

0.4443

0.4027

0.6084

0.5158

0.5172

IW-PSNR

0.7800

0.6967

0.7165

0.6508

0.5255

0.6592

0.6715

0.6267

SSIM

0.7963

0.6058

0.7223

0.6939

0.5768

0.6907

0.6810

0.6615

MS-SSIM

0.8044

0.6478

0.7203

0.7029

0.6568

0.7393

0.7119

0.7116

IW-SSIM

0.8175

0.6842

0.7339

0.7537

0.6636

0.7529

0.7343

0.7240

 


Zhou Wang's Homepage

Created Jan. 14, 2010

Last updated June 8, 2011