MUG: A Parameterless No-Reference JPEG Quality Evaluator Robust to Block Size and Misalignment
This work addresses the need for simple, robust quality assessment in image processing, though it appears incremental as it builds on existing gradient-based approaches.
The paper tackles the problem of no-reference image quality assessment for JPEG compressed images by proposing a parameterless metric called MUG, which is robust to block size and cropping, and shows comparable performance to state-of-the-art methods on multiple benchmark datasets.
In this letter, a very simple no-reference image quality assessment (NR-IQA) model for JPEG compressed images is proposed. The proposed metric called median of unique gradients (MUG) is based on the very simple facts of unique gradient magnitudes of JPEG compressed images. MUG is a parameterless metric and does not need training. Unlike other NR-IQAs, MUG is independent to block size and cropping. A more stable index called MUG+ is also introduced. The experimental results on six benchmark datasets of natural images and a benchmark dataset of synthetic images show that MUG is comparable to the state-of-the-art indices in literature. In addition, its performance remains unchanged for the case of the cropped images in which block boundaries are not known. The MATLAB source code of the proposed metrics is available at https://dl.dropboxusercontent.com/u/74505502/MUG.m and https://dl.dropboxusercontent.com/u/74505502/MUGplus.m.