Originally Posted by pmd918
Yes, the signals are likely treated differently by the projector. If you read up on calibration in the HTPC forum, you will probably figure it out. But it is somewhat confusing, so I'll try to clarify.
Digital video signals have a range from 0 to 255.
A computer monitor interprets 0 as black and 255 as white.
A video device (TV) interprets 16 as black and 235 as white. And there is "important" information encoded below 16 and above 235 that should be sent to the display. To understand the details, read the calibration thread in the HTPC forum.
So when you set the Ruby to "computer", the Ruby is expecting a signal where 0 is black. If your computer is using Overlay to render the video signal, in my system the computer automatically converts the video black (16) to computer black (0), and video white (235) to computer white (255). In this case, the video should display properly because the graphics card changed the signal to display properly on a computer monitor (which is what you created by setting the Ruby to "computer"). Ironically, this is not the best scenario because the projector is not receiving the "blacker-than-black" and "whiter-than-white" information. It is lost when the computer does the conversion.
Now, take the same case, except this time the computer is using VMR9 for the video rendering. In this case (which is likely your situation), the computer does not convert video black (16) to computer black (0). So with the Ruby set to "computer", the projector is expecting a level of 0 to correspond to black, when actually the computer wants 16 to be black. This is the "mismatch" that MarcusInMD was referring to. As a result, the projector displays 16 as gray. That's why your image likely looks washed out. Blacks are gray, whites are gray. The fix for this would be to re-calibrate the display, but why bother, just use the other projector setting (read next paragraph).
So, assuming that you're using VMR9, conversions are not being made. If you set the Ruby to "Video GRB", the Ruby is now expecting Black to be 16, and white to be 235, exactly what your computer is outputting. Bingo, correct picture. No re-calibration necessary. Plus, the display is receiving the blacker-than-black and whiter-than-white information, as it should. (Note: in this configuration, when your computer is displaying normal "computer stuff", the brightness/contrast will not be correct. But who cares, the video is what we're interested in. For gaming, it might be necessary to change the Ruby to the "computer" setting).
Bottom line, if you are using Overlay on the HTPC, chances are that "computer" setting on the Ruby will give you the correct video. If you are using VMR9 on the HTPC, the "video GRB" setting should give you the correct video.
This is how it works on my HTPC. YMMV
Hope this is not confusing, and hope it helps.