Originally Posted by DERG
I guess where I'm confused is, what portions of the White Clipping Pattern should be flashing or not flashing?
Ideally all the bars in the pattern would flash like hwjohn commented, and at minimum at least 233-234 should always flash. Don't expect this pattern to tell you where to generally set your contrast control like with the brightness pattern. Your colorimeter is a far better tool for determining where to set contrast, and this pattern is simply a tool to quickly show what's happening with the above white grayscale.
If the range from 235-254 should be flashing, then I basically have my contrast just above center.
Ideally this would be what would be expected to be seen, because commercial video appears to contain information in this range.
The flashing area has a reddish cast to it as well.
The pattern is gray, so the cast should vary depending upon your grayscale controls. Lowering contrast further might also affect how much color shift there is across the portion of the grayscale displayed in the pattern.
If the range from 235-254 should NOT be flashing, then I basically have my contrast nearly all the way up which washes (clips?) the flashing out.
This sort of clipping or crushing levels with a higher contrast is expected because the display only has a certain amount of available contrast (some displays will not allow this behavior).
In an ideal world the display would have an infinite available contrast, it would increase in brightness from 16 to 254 along a certain gamma, there would never be any color shift through any of the grayscale, and that would mean 233-253 would be gray and always flash with this pattern. In the real world though a display only has a certain amount of available contrast, the gamma might vary depending on where the contrast control is set, there might be more color shift in the grayscale if the contrast is set high, and some people are going to prefer to clip some of the range from 235-254 to get a brighter white (235 is defined as white) even though that means losing some information contained on the disk. Different display types will vary to some extent for what happens for the grayscale (any color shift) and gamma, so that along with personal preference is why I cannot say where to set contrast based on this pattern. You have a colorimeter so you can get a better idea of what is happening with grayscale and gamma depending on different contrast settings, and this pattern can simply show how much information is being crushed near the high end of the grayscale depending upon the setting.
To put things simply, when setting contrast you want to look at things like:
1) The light output for white - illuminance or luminance measurement for white
2) Gamma - how light measurements change across the grayscale
3) Color of the grayscale, including any shifts in color across the grayscale
4) If there's any crush or clip happening, especially below 235 (purpose of the discussed pattern)