Originally Posted by 5150Joker
When i run the black clipping pattern through media player classic on my PC via HDMI to the 500M, I can never see the full spectrum of flashing bars even if I turn up the brightness to full.
Generally this is to be expected, because you're using a computer.COMPUTER AND VIDEO LEVELS
Computers and video use different ranges for black to white. With computer levels black is expected at 0 and white at 255, and sometimes computer levels are called Full or 0-255. On the other hand with video black is at 16 and white at 235, video also allows for 1-15 below black and 236-254 above white information that isn't necessarily expected to be displayed, and sometimes video levels are called Limited or 16-235. Blu-ray or DVD use video levels, so the Black Clipping Pattern shows levels from 1-25 with 16 being black.
By default most computers will decode video and expand it to match the Full range, so 16 from the video goes to 0 and 235 ends up at 255 and the information outside the 16-235 range is lost. What this means for the Black Clipping Pattern is that 17-25 are the only bars that are able to flash if video is expanded to computer levels. Even if video is expanded to computer levels the Black Clipping Pattern can still be used to set brightness on the TV, just set brightness to the lowest setting where the bar marked 17 just barely flashes.
If it is a problem with the ATi settings, does anyone know a way to remedy this so I can do a proper calibration?
If 17-25 flash on the Black Clipping pattern, you can set the brightness control on the display. One complication can be that by default most TVs expect a Limited or video input, rather than a computer input. If you are sending computer levels to your TV you might need to change a setting on the display to expect a Full range. At least that's how my Sony works, by default it expects a video input and it's best to set the TV to Full if the input uses computer levels.
In the ATI control panel the Avivo Video area is generally the place that controls video expansion. There is another set of brightness and contrast controls in the ATI panel under the "color" heading, but I would suggest leaving those controls at their default settings. On my card if I set the Avivo Video brightness to 16 and the Avivo Video contrast to 86 then the whole video range seems to be passed to the TV and Limited can be used at the display. I've read that FFdshow can also be used in the same way to retain the whole Limited range in a computer output, but the complication with either option is that then black for video doesn't match black for general computer use. On the other hand if you leave the Avivo Video brightness at 0 while setting the Avivo Video contrast to the high 90s it's possible to retain some above white from the video (CRT appears to display some above white), while leaving black at the same level for video and computer use.
Anyway I just tried to touch on a few main points:
- Video and computers use different ranges for black and white
- By default computers generally expand video levels to computer levels, which cuts off the 1-15 information shown on the Black Clipping Pattern
- You may need to set the display to expect a Full output from a computer
- There may be different ways for how you can deal with how your computer outputs video if you wish to change the default behavior