When using an HDMI transmitter, it is important to make the sure that the Y1Y0 data in the AV infoframes matches the color space of the video being transmitted. The following shows actual examples of what happens when video is transmitted with the correct/incorrect color space info.
RGB444 Designated/Decoded as RGB444:
RGB444 Designated/Decoded as YCbCr444:
RGB444 Designated/Decoded as YCbCr422:
YCbCr444 Designated/Decoded as RGB444:
YCbCr444 Designated/Decoded as YCbCr444:
YCbCr444 Designated/Decoded as YCbCr422:
YCbCr422 Designated/Decoded as RGB444:
YCbCr422 Designated/Decoded as YCbCr444:
YCbCr422 Designated/Decoded as YCbCr422:
As you can see, it is very important to make sure color space info is correct!