United States Patent im
Ngai
[54] COLOR CONTROL FOR ON-SCREEN DISPLAY IN DIGITAL VIDEO
[75] Inventor: Chuck Hong Ngai. Endwell, N.Y.
[73] Assignee: International Business Machines
Corporation. Armonk. N.Y.
[21] Appl. No.: 643,651
[22] Filed: May 6, 1996
[51] IntCl.6 G09G5/06
[52] U.S. CI 345/199; 345/203; 345/153;
345/509
[58] Field of Search 345/112-115. 150-155.
345/507. 186. 509, 199. 203
[56] References Cited
U.S. PATENT DOCUMENTS
4,683,466 7/1987 Holtey et a! 345/510
4,692,757 9/1987 Tsuhara et al 345/116
4,757,470 7/1988 Bruce et al 345/435
4,771,275 9/1988 Sanders 345/186
5,043,917 8/1991 Okamoto 345/515
5,201,027 4/1993 Casini 395/107
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US005784055A
[ii] Patent Number: 5,784,055 [45] Date of Patent: Jul. 21, 1998
5,258,747 11/1993 Oda et al 345/153
5,270,688 12/1993 Dawson et al 345/150
5,291,188 3/1994 Mclntyre 345/509
5,430,465 7/1995 Sabella et al 345/199
5,502,462 3/1996 Mical et al 345/507
5,572,235 11/1996 Mical et al 345/150
5,596,693 1/1997 Needle et al 345/474
5,684,895 11/1997 Harrington 345/199
Primary Examiner—Matthew M. Kim
Assistant Examiner—U. Chauhan
Attorney, Agent, or Firm—Richard M. Goldman; John R.
Pivnichny
[57] ABSTRACT
A method of performing color control in a digital video decoder while minimizing memory bandwidth. A decoded color image bit map is stored in a RAM in lines corresponding to horizontal lines of pixels. Each line also has dedicated bytes for a corresponding color look up table comprising a control field and color address fields. Entries in separate preloaded color component tables are addressed by the color address fields. A transparency bit in the control field is used to select modifiers to the data in the address fields for transparency mode.
10 Claims, 5 Drawing Sheets
