Visually lossless compression of digitized radiographs based on contrast sensitivity and visual masking

Damon Michael Chandler; Nathan L. Dykes; Sheila S. Hemami

doi:10.1117/12.595614

6 April 2005 Visually lossless compression of digitized radiographs based on contrast sensitivity and visual masking

Damon Michael Chandler, Nathan L. Dykes, Sheila S. Hemami

Proceedings Volume 5749, Medical Imaging 2005: Image Perception, Observer Performance, and Technology Assessment; (2005) https://doi.org/10.1117/12.595614
Event: Medical Imaging, 2005, San Diego, California, United States

Abstract

A visually lossless compression algorithm for digitized radiographs, which predicts the maximum contrast that wavelet subband quantization distortions can exhibit in the reconstructed image such that the distortions are visually undetectable, is presented. Via a psychophysical experiment, contrast thresholds were measured for the detection of 1.15-18.4 cycles/degree wavelet subband quantization distortions in five digitized radiographs; results indicate that digitized radiographs impose image- and frequency-selective effects on detection. A quantization algorithm is presented which predicts the thresholds for individual images based on a model of visual masking. When incorporated into JPEG-2000 and applied to a suite of images, results indicate that digitized radiographs can be compressed in a visually lossless manner at an average compression ratio of 6.25:1, with some images requiring visually lossless ratios as low as 4:1 and as great as 9:1. The proposed algorithm thus yields images that require the minimum bit-rate such that the reconstructed images are visually indistinguishable from the original images. The primary utility of the proposed algorithm is its ability to provide image-adaptive visually lossless compression, thereby avoiding overly conservative or overly aggressive compression.

Citation Download Citation

Damon Michael Chandler, Nathan L. Dykes, and Sheila S. Hemami "Visually lossless compression of digitized radiographs based on contrast sensitivity and visual masking", Proc. SPIE 5749, Medical Imaging 2005: Image Perception, Observer Performance, and Technology Assessment, (6 April 2005); https://doi.org/10.1117/12.595614

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