公开(公告)号：BR9002738A

公开(公告)日：1991-08-20

申请号：BR9002738

申请日：1990-06-11

Applicant: IBM

Inventor： BAYLEY MICHAEL W R ,  YANKER PETER CORNELIUS

IPC: G06T3/00 ,  G09G5/393 ,  G06F15/62

公开(公告)号：CA2012798C

公开(公告)日：1994-11-08

申请号：CA2012798

申请日：1990-03-22

Applicant: IBM

Inventor： BAYLEY MICHAEL W R ,  YANKER PETER C

IPC: G06T3/00 ,  G09G5/393 ,  G09G5/00

Abstract: DIGITAL IMAGE OVERLAY SYSTEM AND METHOD A data processing system is described which includes, among others, three memory areas: a source memory which is addressed in planar, data unit increments and stores display data units on a bit per plane basis; a target memory for storing display data units in a manner suitable for operation of a display unit; and a window buffer for transferring display data units from the source memory to the target memory. The system includes apparatus for inhibiting certain data units from the source memory from overwriting data units already in the target memory. The method of the invention comprises first accessing a plurality of data units from the source memory and then logically determining if all bits of each accessed data unit meet a predetermined criteria. Each data unit found to meet the predetermined criteria is inhibited from altering any data unit already in the target memory.