Arachnotron
23rd October 2004, 19:32
So, in other words, the superblack and superwhite values are already present in the broadcast itself.
To some extend they must be. A bandwidth limited analog signal will always have overshoots. If you digitize that, some samples will be below or above the 16-235 range.
It would not really matter much, since on a normal TV set superblack and white would look like normal black and white anyway. Only by messing with the brightness or sampling the signal can you make it visible.
Also, most cards use the difference between blanking level and horizontal sync to calibrate the white and blacklevels. If there is something wrong with that relation in the source, you can get out of range values too.
And, broadcast is a general term and comprises a variety of sources, processes in many different ways. There is a lot of cr*p in the airways. Not everything will be in spec.
2) Does that mean that the broadcast is displayed incorrectly on the tv? Because like I said "(...) the video is simply too dark. Details in certain (parts of) scenes are invisible because of that.". Depends on how your TV set is tuned. Almost no TV set has blacklevel set correctly out of the shop. To determine something like that, you first must calibrate your TV set using a greyscale pluge.
To some extend they must be. A bandwidth limited analog signal will always have overshoots. If you digitize that, some samples will be below or above the 16-235 range.
It would not really matter much, since on a normal TV set superblack and white would look like normal black and white anyway. Only by messing with the brightness or sampling the signal can you make it visible.
Also, most cards use the difference between blanking level and horizontal sync to calibrate the white and blacklevels. If there is something wrong with that relation in the source, you can get out of range values too.
And, broadcast is a general term and comprises a variety of sources, processes in many different ways. There is a lot of cr*p in the airways. Not everything will be in spec.
2) Does that mean that the broadcast is displayed incorrectly on the tv? Because like I said "(...) the video is simply too dark. Details in certain (parts of) scenes are invisible because of that.". Depends on how your TV set is tuned. Almost no TV set has blacklevel set correctly out of the shop. To determine something like that, you first must calibrate your TV set using a greyscale pluge.