- Written by Staff
- Published on 10 January 2008
My first stop at this yearâ€™s CES was at the Dolby booth where they are now trying to transform the quality of video displays in the same way that they have improved the audio side of AV. Dolbyâ€™s new technology improves the brightness and contrast ratio of LCD flat panel displays. Dolby calls this technology High Dynamic Range or HDR. Dolbyâ€™s HDR is based on local dimming of an array of more than 1000 LEDs that are used to backlight the LCD panel. Local dimming allows the LEDs associated with a bright area of the display to be brighter than those associated with darker areas of the display. In the past, the whole LCD panel would be equally backlighted by a uniform light source. Local Dimming can potentially extend the dynamic contrast ratio of a display device well beyond the native contrast ratio of the LCD panels. In this respect, it is very similar in concept to the use of an iris or lamp dimming in projector technology, with the important distinction that with projectors, the iris dims the whole display, whereas with local dimming only the darker areas are dimmed. Local dimming therefore can improve the contrast ratio within a frame as well as the on/off contrast ratio .
Dolby had two otherwise identical LCD displays, one with an un-modulated light source for the backlighting, and one using local dimming. The difference in the two images was dramatic, with the HDR display appearing to have a much higher gamma, with brighter highlights and darker blacks in the same image. It seemed a bit overdone, but very suggestive how much punch such technology could add to a display.
Toshiba had a very similar technology display, two LCD displays, one with LED backlighting and local dimming the other without. In this case, with the enhanced image looking much more realistic with obviously deeper blacks.
Toshiba also had a poster explaining the local dimming technology.
LG was also displaying an LCD display with local dimming (above) as was Sharp and Samsung.
Panasonic featiured an LED backlighted LCD display, noting that LEDs allowed two times the light output with the same amount of power consumption or as shown about the same brightness with half the power.