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本帖最后由 bluebay999 于 2018-7-31 15:44 编辑
哈哈,才在刚发的那帖里看到,原文:
ABL
Another of the often overlooked potential issues with HDR has to do with the (legal) need to limit the power requirement of the display, as obviously extreme brightness causes excessive power consumption. That in itself is a cause for concern, based both on the power costs, and potential environmental issues. Hopefully, both those can be overcome with more efficient display back-lighting technologies.
However, in an attempt to overcome extreme power requirements, just about all HDR displays use one form or another of ABL (Auto Brightness Limiting - often called Power Limiting in HDR terminology). In very simple terms ABL reduces the power to the screen dependant on the percentage screen area that goes over a predetermined brightness level, so reducing the overall brightness of the scene. The PQ HDR specification defines what is known as MaxCLL (Maximum Content Light Level) and MaxFALL (Maximum Frame-Average Light Level) which are intended to be part of the HDR mastering meta-data, from which the viewing display will calculate how to show the image, limiting potentially high power requirements.
Obviously, this causes the same image to be viewed differently on different displays, with different shots of the same scene, with different framing, to also be seen differently on the same display as the average picture brightness level will be different depending on the shot framing, potentially causing different power limiting to be applied by the display in an almost perceptually random way.
Such variations cause serious issues with accurate display calibration and image playback(这种变化导致精确的显示校准和图像回放的严重问题).
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