Image analysis – Image compression or coding – Gray level to binary coding
Patent
1997-02-21
1999-09-14
Coles, Edward L.
Image analysis
Image compression or coding
Gray level to binary coding
382270, 382252, 358457, 358466, H04N 1405, G06K 938
Patent
active
059534591
ABSTRACT:
A plurality of uniform density pixel matrices Di are prepared so that each matrix Di will have all pixels of a uniform density i. First, in S110, the pixels of one uniform density pixel matrix Di are converted into binary values (0 or 1) while performing an error diffusion operation. Thus obtained binary value pixel matrix Fi is stored in the working memory 14. Then, while the uniform density value i is repeatedly incremented, the above-described converting-and-storing processes are repeated. Afterward, binary values throughout all the binary value pixel matrices are summed at each pixel position. Thus, in S150, an accumulated value matrix M1 is produced to have a corresponding element constructed from the total value. Next, threshold values of a dither matrix DM are determined based on the elements of the matrix M1. That is, the threshold values are determined one by one using the elements of the matrix M1 from its element having the lowest value. Thus obtained threshold values are stored in the dither matrix storage memory 16 in S170.
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Komiya Ryohei
Ueda Masashi
Brother Kogyo Kabushiki Kaisha
Coles Edward L.
Davis Joe
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