CompuServe Thread

#3DS R3 Gamma Values

3 messages in this thread
#66910From: GEORGE MENDOZANov 17, 1993 12:14 AM
I have a ATI Mach 32 Ultra Pro and a Targa + 64 Frame buffer in my PC . What I would like to know is how to calibrate my Targa + 64 per the instructions on pages 74-77 in the 3ds r3 installation guide. I've tried to disable my Targa + 64 Gamma correction, per the instructions in my Targa + reference guide pg 1-15. I ran Targa + configuration program and set the Gamma correction to 0 .1. Then I executed the Targa + 64 bat file before running 3DS R3 and still had Gamma compensation values close to 1. Also, I don't see any differences in NTSC video renderings at different values.
#66938From: Don LandisNov 17, 1993 9:02 AM
You might want to extract old threads on this subject about a month ago such as "GAMMA-GAMMA" We all discovered a problem with the Gamma calibration in 3DS and the targa+ boards. Gary Yost is away for the month so he will have to address the issue later. John Ellis and I did some considerable testing and found that the best thing to do was to use Tmode 11 to install your targa+ then set the gamma in 3DS for 2.2 for the framebuffer as well as 2.2 for file input. Don't worry about the gray boxes. John Ellis found the gray boxes to match if you were using an RGB out from the targa+ but most of us use NTSC or Y/C out and in this case the gray boxes don't work. This might be the only "bug" in 3DSr3 found to to date. Note: the gamma seems to work fine for VGA monitor with settings reported by forum members between 1.5-2.0 depending on the different monitors being used.
#67003From: David RhotenNov 17, 1993 4:33 PM
Just to supplement Don's statement, you must either use TMODE 11 to initialize the Targa, not a batch file created by TCONFIG. (You can use the TCONFIG batch file if you follow it with TARGEDIT lutBypass 1). The reason is that TCONFIG automatically turns on the Targa's internal Gamma correction. The reason the boxes _still_ won't align right visaully is because of definitions inherent in the NTSC standard. I'm going to gather the GAMMA thread and upload it tonight. Dave