ugogan@ecsvax.UUCP (Jim Gogan) (10/09/87)
Am passing along the following request for a colleague. Please mail
any info to me and Ill forward it to the requester. Thanks!
Does anyone know of a frame grabber (screen snap-shot)
that takes full advantage of the EGA 256K graphics?
Should do 512 squared frame with all 256 shades of each
color. Any sources for further investigation will also be apreciated.
Thanks in advance.
Send info to:
Jim Gogan (ugogan@ecsvax)
University of North Carolina at Chapel Hill
--
Jim Gogan mail:ugogan@ecsvax (UUCP/BITNET)
Microcomputing Support Center
University of North Carolina at Chapel Hill
Chapel Hill, NC 27514jru@etn-rad.UUCP (John Unekis) (10/12/87)
In article <4010@ecsvax.UUCP> ugogan@ecsvax.UUCP (Jim Gogan) writes: >Does anyone know of a frame grabber (screen snap-shot) >that takes full advantage of the EGA 256K graphics? >Should do 512 squared frame with all 256 shades of each >color. Any sources for further investigation will also be apreciated. .... Sorry to disappoint you, but it cant be done. If you are talking about a frame grabber(video digitizer) that would simply use the EGA memory as a buffer for images without trying to display them , it would sort of work, except that the EGA memory is organized as 32Kbyte planes that overlay each other in memory, and you must set a register to mask the one(s) that you are reading/writing to. If you mean that you would like the EGA to display a frame that is 512x512 with eight bits per pixel it is completely impossible. The EGA uses four bits per pixel, which are translated as an offset into a sixteen element lookup table. The lookup table is 6 bits wide - giving you the net effect of selecting 16 out of a possible 64 colors at any given time. The output from the lookup table is physically sent to the monitor as 2 bits per color gun, so only four shades of each color can be achieved. If you really need a better display try the new VGA, or look for some EGA compatible products to be announced at comdex.