Kwan L Wong

US Patent:

40329780, Jun 28, 1977

Filed:

Jan 20, 1975

Appl. No.:

5/542530

Inventors:

Kwan Y. Wong - San Jose CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

H04N 140
H04N 122

US Classification:

358283

Abstract:

Gray scale levels are converted to pseudo halftone print by a pseudo halftone generator which reduces Moire effects. The generator includes a comparator and an incrementing cyclic counting mechanism to compare the gray scale level to the cyclicly generated reference count for each print position in a print line to generate a print signal upon the level being greater than the count. The cyclicly generated count is incremented by a preselected number N for each print position and recycles at the square of that number (N. sup. 2). The square value may also be selected as the maximum level of the gray scale range. N adjacent print lines may be grouped together to form a series of (N. times. N) matrices. The reference or lowest count value for each of the lines in a matrix is different and they range from zero to N-1.

US Patent:

41504003, Apr 17, 1979

Filed:

Mar 31, 1977

Appl. No.:

5/783374

Inventors:

Kwan Y. Wong - San Jose CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

H04N 712
H04N 100

US Classification:

358260

Abstract:

A coarse scanning device produces analog signals that are encoded and compressed to distinguish between and represent the white background and potentially the all black elements of the character by run length codes and at least the edge of the black character by grey level values. The grey level information is decoded to activate a fine print device where the numer of print dots in a matrix is equal to the grey level values. The placement of the print dots are biased according to pattern matrices designed to bias the dots toward the character. The pattern matrices are acquired by determining the sums of the grey level values of various groups of picture elements peripheral to the picture element being decoded.