Introduction

GSM (Gradient Similarity based Metric) index is presented by Liu et al. 2012 [1].

Source Code

Source code is provided by the creators at https://1drv.ms/u/s!Ag8dxliAh_DPgVvk_xjw63DnGVFZ?e=3tjM7c

Usage Notes

1. Do not change the default parameter settings.

2. imRef = rgb2gray(imRef);
    imDis = rgb2gray(imDis);
    metricValue = GSM(double(imRef),double(imDis));

Evaluation Results

The results (in Matlab .mat format) are provided here. Each result file contains a n by 2 matrix, where n denotes the number of distorted images in the database. The first column is the IFC values, and the second column is the mos/dmos values provided by the database. For example, you can use the following matlab code to calculate the SROCC and KROCC values for GSM values obtained on the TID2008 database:

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matData = load('GSMOnTID.mat');
GSMOnTID= matData.GSMOnTID;
GSM_TID_SROCC = corr(GSMOnTID(:,1), GSMOnTID(:,2), 'type', 'spearman');
GSM_TID_KROCC = corr(GSMOnTID(:,1), GSMOnTID(:,2), 'type', 'kendall');

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The source codes to calculate the PLCC and RMSE are also provided for each database. This needs a nonlinear regression procedure which is dependant on the initialization of the parameters. We try to adjust the parameters to get a high PLCC value. For different databases, the parameter initialization may be different. The nonlinear fitting function is of the form as described in [2].

Evaluation results of GSM on seven databases are given below. Besides, for each evaluation metric, we present its weighted-average value over all the testing datasets; and the weight for each database is set as the number of distorted images in that dataset.

Reference                

[1] A. Liu, W. Lin, and M. Narwaria, "Image quality assessment based on gradient similarity," IEEE Trans. Image Process., vol. 21, no. 4, pp. 1500-1512, 2012.

[2] H.R. Sheikh, M.F. Sabir, and A.C. Bovik, "A statistical evaluation of recent full reference image quality assessment algorithms," IEEE Trans. on Image Processing, vol. 15, no. 11, pp. 3440-3451, 2006.

Created on: Dec. 04, 2013

Last update: Dec. 04, 2013