[Warner306]

tone map HDR using pixel shaders: output video in HDR format

Advantages:

• This can work with the existing HDR tone curve of the display that may already be fairly well-optimized and most often tracks the 0-100 nits SDR range 1:1 with the PQ EOTF;
  
• You have less control over the brightness, but it is easier to select a real display peak nits because you are only doing some processing for the display and not all of it;
  
• The output can still take advantage of the extra peak brightness offered by the display's HDR mode to maintain a higher APL and provide the specular highlights with greater brightness and impact. It can also complement a display that uses dynamic tone mapping that should react to the precise brightness of the remapped RGB values rather than have to interpret the static metadata output by madVR;
  
• madVR uses some extra processing to make compressed parts of the image sharper than the display should be able to produce, and possibly more accurate gamut mapping.
  

Disadvantages:

• Double processing can be an issue. madVR may only have partial control over the tone mapping. A second tone curve could be applied if the display uses a fixed tone curve for all HDR sources. This may result in inaccurate colors and some clipping if the processing of the display doesn't match well with madVR;
  
• There is less control over the brightness of the display curve;
  
• It is more difficult for madVR's dynamic tone mapping to work when the display uses static tone mapping (one curve for the whole movie). madVR will still dynamically compress the brightest highlights for the display as they appear, but the display may further compress the image to some extent with a static tone curve;
  
• It is difficult to predict how the display will react to the metadata output by madVR making it difficult to estimate the best value for the real display peak nits. Certain changes to the metadata may result in a very different selection of tone curves by the display (or in an ideal scenario, no tone mapping curve may be used by some displays).