Recently, image communications are becoming increasingly popular, and there is a growing need for consumers to be provided with high-quality services. Although the image communication services already exist over third-generation wireless networks, there are still obstacles that prevent high-quality image communications because of limited bandwidth. Thus, more research is required to overcome the limited bandwidth of current communications systems and achieve high-quality image reconstruction in real applications. From the point of view of image processing, core technologies for high-quality image reconstruction are face hallucination and compression artifact reduction. The main interests of consumers are facial regions and several compression artifacts inevitably occur by compression; these two technologies are closely related to inverse problems in image processing. We review recent studies on face hallucination and compression artifact reduction, and provide an outline of current research. Furthermore, we discuss practical considerations and possible solutions to implement these two technologies in real mobile applications.
Image quality and depth perception rates in three-dimensional television (3-D TV) are undesirably decreased by coding due to the loss of high-frequency components caused by a block-based discrete cosine transform transform. Representative coding artifacts are blocking artifacts that seriously degrade the picture quality and depth perception rates. We propose a new blocking artifact reduction method in 3-D TV using an overcomplete 3-D dictionary. We first generate the overcomplete 3-D dictionary from natural and depth images using the k-singular value decomposition algorithm. Then, we perform deblocking using the 3-D dictionary after estimating an error threshold of the objective function by the third-order polynomial fitting. Experimental results demonstrate that the proposed method can effectively reduce annoying blocking artifacts in compressed 3-D images, i.e., video-plus-depth, and generate high-quality 3-D stereoscopic views.
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