Can you explain just how many levels should be visible in each square in the clipping levels screen?
If you are talking about the pattern called clipping, then all of them.
I know people are using this pattern to set contrast, that was not its original intention. It was designed to show the bug in the Silicon Image HDMI transmitter/recievers. The way the pattern works is like this:
1. If white is clipped and RGB is not, this is the HDMI bug. This works because the white values are above 235 in Y. The RGBs will not clip because they are all within 16-235 in Y'CbCr. They only fall outside of 16-235 when converted to RGB.
2. If the RGB are clipped and white is not, this is often caused by:
-a. Color set incorrectly. usually too high.
-b. Could also be caused by RGB gain controls being set too high.
3. If they are all clipped, it can be caused by contrast set too high or conversion to PC levels. e.g. 16-235 is expanded to 0-255.
4. If green is clipped, but white, red and blue are not, this is usually caused by incorrectly using the 601 matrix instead of the 709 matrix when converting to RGB. Here is an example of that: