High Dynamic Range / Wide Color Gamut (HDR/WCG) Project
The HDR Project
What is High Dynamic Range (HDR)?
Human eyes can perceive approximately five orders of luminance magnitude at a time, but current capture and display technologies are limited to, at most, three orders of magnitude.
The aim of HDR imaging : capture and display these 5 orders of magnitude with high fidelity.
The aim of the VQEG HDR project is to develop methods for assessing the quality of HDR video.
HDR technologies aim at filling the gap between capture and display technologies and the abilities of the human visual system. This will provide a more realistic visual experience compared to current Low Dynamic Range (LDR) imaging. All of the current technologies on the market are LDR but it is felt that within the next few years HDR will be ready for commercial release and we need to be ahead of it to understand the user benefit and how to measure quality.
New (non-exhaustive) issues regarding visual quality broken into categories:
Image capture: Since almost no native HDR sensor exists, the capture step is multi-phased. Natural HDR imagery and video currently cannot be acquired. Consequently HDR content is built up by fusing multiple LDR images. Many quality issues can arise from such processing(geometric distortions, ghosting, noises, etc.).
Image display: HDR display technology is a little bit more advanced than capture, but is still comes with its issues: much higher peak luminance (which require adapting experimental conditions), backlight LEDs bleeding, etc. There are also issues related to power consumption, display life, and other items that might impact the user settings for the end technology.
Content delivery: Coding and transport of HDR content need also to be investigated since it requires much higher bit allocation than current coding standard support. We already have an explosion of traffic on networks due to standard and high definition video transport and so we need to determine moving forward how we want to address bandwidth concerns.
Lastly, HDR and LDR technologies will have to coexist for some time. HDR to LDR operations (tone mapping) and LDR to HDR operations (inverse tone-mapping) will need to be used. These operations can cause distortion on the original content and even change the original artistic intention.
All these new issues need to be studied in order to be able to provide accurate subjective assessment methodologies and objective quality metrics for HDR content.