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Conversion of Image Resolution

IP.com Disclosure Number: IPCOM000034849D
Original Publication Date: 1989-Apr-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 2 page(s) / 65K

Publishing Venue

IBM

Related People

Asano, H: AUTHOR [+3]

Abstract

This article describes an algorithm for converting a resolution of an original image by comparing the gray levels of picture elements (pels) of the original image with the plural dither matrices to generate binary data which result from the comparison and determining the number of black and white pels in the converted image. Fig. 1 shows an original image 1, dither matrices 2, 3 and 4, resultant binary data 5, 6 and 7, and a converted image 8. The values in the original image 1 and the dither matrices 2, 3, and 4 are represented by hexadecimal notation (X). For example, the value X'65' at a pel position (2, 2) in the original image 1 means the binary value '01100101'. As shown in Fig. 2, gray levels between a real white level and a real black level are divided into 256 levels. Fig.

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Conversion of Image Resolution

This article describes an algorithm for converting a resolution of an original image by comparing the gray levels of picture elements (pels) of the original image with the plural dither matrices to generate binary data which result from the comparison and determining the number of black and white pels in the converted image. Fig. 1 shows an original image 1, dither matrices 2, 3 and 4, resultant binary data 5, 6 and 7, and a converted image 8. The values in the original image 1 and the dither matrices 2, 3, and 4 are represented by hexadecimal notation (X). For example, the value X'65' at a pel position (2, 2) in the original image 1 means the binary value '01100101'. As shown in Fig. 2, gray levels between a real white level and a real black level are divided into 256 levels. Fig. 2 also shows the ranges covered by the dither matrices 2, 3 and 4.

(Image Omitted)

It is assumed that 4x4 pels of the original image, as surrounded by a thick line, are being processed to generate the converted or double resolution image 8. The gray level values of the pels in the original image 1 are compared with the threshold values of the dither matrices 2, 3 and 4 to generate the binary values 5, 6 and 7, respectively. For example, the gray value X'10' at the pel position (1, 1) of the original image 1 is sequentially compared with the threshold values X'CO' of the dither matrix 2, X'CO' of the dither matrix 3 and X'EO' of the dither matrix 4, whereby the binary data 1, 1 and 1 are generated, as shown by circles in Fig. l. In the comparison,...