A new object based quality metric based on SIFT and SSIM

We propose a full reference visual quality metric to evaluate a semantic coding system which may not preserve exactly the position and/or the shape of objects. The metric is based on Scale-Invariant Feature Transform (SIFT) points. More specifically, Structural SIMilarity (SSIM) on windows around the SIFT points measures the compression artifacts (SSIM_SIFT). Conversely, the standard deviation of the matching distance between the SIFT points measures the geometric distortion (GEOMETRIC_SIFT). We validate our metric with subjective evaluation and reach a Spearman correlation of 0.86 for SSIM_SIFT and 0.74 for GEOMETRIC_SIFT.