Optical EngineeringObjective measurements of video quality using the wavelet transform
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We propose a new method for objective measurement of video quality using the wavelet transform. We exploit the fact that the sensitivity of the human visual system varies over spatiotemporal frequencies. First, in order to compute spatial-frequency components, the wavelet transform is applied to each frame of source and processed videos. Then, the difference (squared error) of the wavelet coefficients in each subband is computed and summed, producing a difference vector for each frame. By repeating this procedure for all the frames of a video, we obtain a sequence of difference vectors, and then the average vector is computed. Each component of this average vector represents a difference in a certain spatial frequency. In order to take into account the temporal frequencies, we also propose a modified 3-D wavelet transform. In either case, a single vector represents the difference between the source and the processed video. From this vector, a number is computed as a weighted sum of its elements and is used as an objective score. In order to find the optimal weight vector, an optimization procedure is proposed. Experimental results show that the proposed method compares favorably with the current objective methods for video quality measurement.