Adaptive Selection Of Threshold Matrix Size For Pseudo-Gray Rendition Of Images

Matthias F. Carlsohn; Philipp W. Besslich

doi:10.1117/12.944877

4 December 1984 Adaptive Selection Of Threshold Matrix Size For Pseudo-Gray Rendition Of Images

Matthias F. Carlsohn, Philipp W. Besslich

Proceedings Volume 0504, Applications of Digital Image Processing VII; (1984) https://doi.org/10.1117/12.944877
Event: 28th Annual Technical Symposium, 1984, San Diego, United States

Abstract

Dither rendition of images is a well-known method to produce pseudo-gray scale images using bi-level output devices. Moreover, it reduces the data to 1 bit/pixel. For fixed sub-picture (matrix) size there is, however, a contradiction between resolution and the dynamic range of the gray scale. In this paper we show how this conflict may be overcome using variable resolution. For this purpose we introduce a detail-dependent segmentation of the image into variable-size subpictures. We describe first the construction of suitable dither matrices of size 2mx2m, with m = 2,3,4. The next section deals with adaptation criteria to obtain the appropriate pseudo-pixel size. A major aspect of the paper is the fast in-place computer method to break the full picture up into subpictures of appropriate size. This sub-picture size depends adaptively on the local "activity" of the picture. The method is demonstrated using 8-bit test pictures and shows good gray scale rendition and sufficient de-tail resolution.

Citation Download Citation

Matthias F. Carlsohn and Philipp W. Besslich "Adaptive Selection Of Threshold Matrix Size For Pseudo-Gray Rendition Of Images", Proc. SPIE 0504, Applications of Digital Image Processing VII, (4 December 1984); https://doi.org/10.1117/12.944877

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