Spatially variant filtering algorithm with adaptive gray-scale quantizer

Mohsen Ghaderi

doi:10.1117/12.58342

19 May 1992 Spatially variant filtering algorithm with adaptive gray-scale quantizer

Mohsen Ghaderi

Proceedings Volume 1657, Image Processing Algorithms and Techniques III; (1992) https://doi.org/10.1117/12.58342
Event: SPIE/IS&T 1992 Symposium on Electronic Imaging: Science and Technology, 1992, San Jose, CA, United States

Abstract

This paper describes an algorithm for enhancing very low-contrast and degraded images. This problem is solved by applying an adaptive image enhancement algorithm to improve the quality and readability of degraded documents. The algorithm is a combination of an adaptive spatial filter and an adaptive gray-scale quantizer. The adaptive spatial variant filter sharpens the image information while suppressing the background noise. It does this in two steps; first, it classifies each image pixel as either signal, background, or noise by using moment estimates in windows of various sizes. The algorithm uses this classification to choose either a high-pass or low-pass filter to filter the image region. The adaptive quantizer is implemented by estimating the average background and foreground levels of the signal and adjusting the quantizer appropriately. The algorithm has been simulated on a wide variety of scanned imagery with significant improvements in image sharpness and contrast, and text legibility. Examples are included.

Citation Download Citation

Mohsen Ghaderi "Spatially variant filtering algorithm with adaptive gray-scale quantizer", Proc. SPIE 1657, Image Processing Algorithms and Techniques III, (19 May 1992); https://doi.org/10.1117/12.58342

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