Kwan Chun 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.

US Patent:

41248708, Nov 7, 1978

Filed:

Mar 31, 1977

Appl. No.:

5/783375

Inventors:

Bruce R. Schatz - Cambridge MA
Kwan Y. Wong - San Jose CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

H04N 712

US Classification:

358260

Abstract:

A directional biasing method enhances the print quality of coarsely scanned characters. A coarse scanning device produces analog signals that are compressed by encoding common information in a run length coding and encoding at least an edge of the character information according to a grey level indication. The data information is reproduced wherein the grey scale information is decoded to represent a finer print than the picture element scanned. The biasing and placement of the dots is set according to the grey scale of the surrounding picture elements. Eight sums are obtained of various groups of three peripheral picture elements corresponding to eight patterns located symmetrically on both sides of 4 bisecting lines, vertical, horizontal and two 45. degree. lines. A particular matrix of print dot placement is selected according to the largest pattern sum among the eight possible cases. The dots in each matrix are designed to being strongly biased toward the direction of the associated pattern.