Wavelet-based foveated image quality measurement for region of interest image coding
Region of interest (ROI) image and video compression techniques have been widely used in visual communication applications in an effort to deliver good quality images and videos at limited bandwidths. Most image quality metrics have been developed for uniform resolution images. These metrics are not appropriate for the assessment of ROI coded images, where space-variant resolution is necessary. The spatial resolution of the human visual system (HVS) is highest around the point of fixation and decreases rapidly with increasing eccentricity. Since the ROIs are usually the regions "fixated" by human eyes, the foveation property of the HVS supplies a natural approach for guiding the design of ROI image quality measurement algorithms. We have developed an objective quality metric for ROI coded images in the wavelet transform domain. This metric can serve to mediate the compression and enhancement of ROI coded images and videos. We show its effectiveness by applying it to an embedded foveated image coding system.