1 April 1997 Improving the visual quality of JPEG-encoded images via companding
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A companding procedure designed to improve the visual quality of monochrome images encoded with the baseline Joint Photographic Experts Group (JPEG) image compression algorithm is described. The companding procedure consists of two pointwise nonlinearities applied to the image, one before and one after the JPEG encoding. In a series of two-alternative forced-choice experiments designed to measure human visual threshold response to these images, it was determined that the average bitrate at the just-noticeable- difference (JND) point for the companded images is less than that for the uncompanded images. In a suprathreshold experiment, the subjects selected the companded images as being less distorted than the uncompanded images in more than 80% of the trials, for image bitrates ranging from 0.4 to 1.0 bpp.
Manish Bakshi, Manish Bakshi, Daniel R. Fuhrmann, Daniel R. Fuhrmann, } "Improving the visual quality of JPEG-encoded images via companding," Journal of Electronic Imaging 6(2), (1 April 1997). https://doi.org/10.1117/12.266868 . Submission:

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