<title>Preprocessing for improved performance in image and video coding</title>

Abstract

In previous work, we have reported on the benefits of noise reduction prior to coding of very high quality images. Perceptual transparency can be achieved with a significant improvement in compression as compared to error free codes. In this paper, we examine the benefits of pre-processing when the quality requirements are not very high, and perceptible distortion results. The use of data dependent anisotropic diffusion that maintains image structure, edges, and transitions in luminance or color is beneficial in controlling the spatial distribution of errors introduced by coding. Thus, the merit of preprocessing is for the control of coding errors. In this preliminary study, we only consider preprocessing prior to the use of the standard JPEG and MPEG coding techniques.Keywords: image coding, video coding, image processing, inhomogeneous diffusion.We study the pre-processing of images and video in two ways. First, by examining the effect of pre-processing on still image quality, as measured by a recently developed perceptually based picture quality scale (PQS). Second, we examine the effect of pre-processing on video coding performance, where noise has a more substantial effect, because the redundancy reduction sought by interframe coding is limited by the unpredictability of the noise from frame to frame. We evaluate the bit rates of encoded pre-processed and original video and compare for the same bit rate the quality of the resulting images either subjectively, using the PSNR, or objectively. We also examine briefly the benefits of post processing . We show an example of reduction of the blocking effect prevalent in DCT that is incorporated in the JPEG and MPEG standards. 22 /SPIE Vol. 2564 O-8194-1923-O/95/$6.OO Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/16/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx SPIE Vol. 2564 /27 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/16/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx

Object Shape Approximation and Contour Adaptive Depth Image Coding for Virtual View Synthesis

“…There are other pre-processing methods that attempt to improve video / image coding efficiency. The work in [22]- [25] apply filters on input videos / images to remove noise. [26] corrects the color value of multiview videos to make them consistent, and [27] evaluates the coding performance of applying a texture image guided filter on the estimated low quality depth map.…”

Quality measurement and use of pre-processing in image compression

“…The CPF is based on a mean curvature di usion algorithm where the local image properties control the di usion. It has been shown that this lter preserves important image structure while e ectively removing noise 12,4,14,13]. For compression, a standard JPEG coder 15] and the be s tperforming wavelet coder obtained from a previous study 19,3] are used.…”

“…Such pre-processing, when combined with a standard lossy or lossless coder, can also result in an improvement in overall coding performance 2, 1,4]. At lower levels of quality, the adaptive lter allows controlled image simpli cation so that the coder can compress it more e ectively.…”

<title>Quantifying coding performance for preprocessed images</title>

“…One option, that we h a ve examined in previous work, is to pre-process the image in an adaptive fashion so as to introduce imperceptible or controlled degradations to the image. 1,2 Such pre-processing, when combined with a standard coder, either lossy or error free, can result in an improvement i n o verall coding performance. 1 Measuring this performance improvement is the subject of this paper.…”

“…1,2 Such pre-processing, when combined with a standard coder, either lossy or error free, can result in an improvement i n o verall coding performance. 1 Measuring this performance improvement is the subject of this paper.…”