Frequently Asked Questions

• Does HDR-VDP-2 report differences in color?

No. However, color information is used to correctly compute photopic (daylight) and scotopic (night vision) luminance, i.e. Purkinje shift.

• Does HDR-VDP-2 work with ordinary (LDR) images?

Yes. You need to specify 'sRGB-display' as the color_encoding parameter and pass an RGB image in which the values range from 0 to 1. This color encoding assumes that the peak luminance of the display is 100 <math>cd/m^2</math>. Note that the matlab function imread will return a matrix of uint8 or unit16, which needs to be converted to the normalized floating point matrix: single(img)/2^8 or single(img)/2^16.

• <math>Q_{MOS}</math> predictions do not match my assessment of quality.

<math>Q_{MOS}</math> predictions were optimized for a range of distortions, including image compression, blocky artifacts, noise and blur. The full list can be found in the Calibration reports. This predictor is likely to be much less accurate for other type of distortions that were not considered. In such situation, the predictor <math>Q</math> could be a better choice.

This section is under construction.