ARM was in the i-Zone showing off its HDR-to-SDR conversion technology. This is technology that was acquired via Arm’s purchase of Apical exactly one year ago. The technology is being aimed at HDR device and set top box makers so they can consider sending out a HDR signal as the main feed and have the STB down convert if the home owner does not have an HDR display. Their core IP can be easily loaded into a SoC chip set.
The company explained that many algorithms to down convert from HDR to SDR use a global tone mapping curve which is likely to lower to overall luminance and may not preserve mid tones very well.
With their approach, they do a pixel by pixel analysis of the surround pixels and apply a tone curve based upon the region. This local tone mapping focus should allow for better preservation of the highlights, midtones and shadow details.
The two images below tell the story. In the top photo, the tone curve is adjusted to bring out more high light details in the clouds. The bottom image shows how a different tone curve can bring out shadow details. The software can also use the light sensor data from an HDR device to adjust the SDR image based upon the local ambient illumination. – CC
