[Warner306]

tone map HDR using pixel shaders: SDR Gamma

Advantages:

• madVR has complete control over the output, especially if the calibrated gamma of the display matches the output gamma from madVR. There is no extra processing by the display;
  
• The relative SDR gamma curve makes it easy to configure the brightness to your liking by adjusting the display target nits up or down;
  
• The dynamic tone mapping used by madVR can adjust the display tone curve throughout the presentation without any interference from the display. Most HDR displays apply static tone mapping based on a single HDR10 static metadata value (MaxCLL or mastering display maximum luminance). Most often this results in a dimmer image than desired and some clipping of specular highlight detail, as the fixed curve is unable to react to the continually varying peak brightness of the video. Static metadata is also known to be wildly inaccurate in many cases.
  

Disadvantages:

• HDR to SDR is more difficult to configure than simple HDR10 passthrough to get a good result;
  
• The SDR gamma curve is relative with many choices for display gamma and the PQ EOTF is absolute, which again makes it more difficult to configure to get a good result;
  
• madVR must use the fixed gamma luminance scale to produce PQ luminance values;
  
• Both HDR and SDR share the same calibration. The result is limited by the calibrated peak brightness of the display in SDR output. If the display uses a strict 100-120 nits SDR calibration, a low dynamic range presentation (not that much different than SDR) can be the result.