visual enhancement with common contrast source material levels off at about 60 LCD local dimming zones. Technology LED-backlit LCDs are not self-illuminating (unlike pure-LED systems). There are several methods of backlighting an LCD panel using LEDs, including the use of either white or RGB (Red, Green, and Blue) LED arrays behind the panel and edge-LED lighting (which uses white LEDs around the inside frame of the TV and a light-diffusion panel to spread the light evenly behind the LCD panel). Variations in LED backlighting offer different benefits. The first commercial full-array LED-backlit LCD TV was the Sony Qualia 005 (introduced in 2004), which used RGB LED arrays to produce a color gamut about twice that of a conventional CCFL LCD television. This was possible because red, green and blue LEDs have sharp spectral peaks which (combined with the LCD panel filters) result in significantly less bleed-through to adjacent color channels. Unwanted bleed-through channels do not "whiten" the desired color as much, resulting in a larger gamut. RGB LED technology continues to be used on Sony BRAVIA LCD models. LED backlighting using white LEDs produces a broader spectrum source feeding the individual LCD panel filters (similar to CCFL sources), resulting in a more limited display gamut than RGB LEDs at lower cost. Television sets described as "LED TVs" are LCD-based, with the LEDs dynamically controlled using the video information (dynamic backlight control or dynamic "local dimming" LED backlight, also marketed as HDR, high dynamic range television, invented by Philips researchers Douglas Stanton, Martinus Stroomer and Adrianus de Vaan The evolution of energy standards and the increasing public expectations regarding power consumption made it necessary for backlight systems to manage their power. As for other consumer electronics products (e.g., fridges or light bulbs), energy consumption categories are enforced for television sets. Standards for power ratings for TV sets have been introduced, e.g., in the US, EU, Australia, and China. A 2008 study showed that among European countries power consumption is one of the most important criteria for consumers when they choose a television, as important as the screen size. Using PWM (pulse-width modulation), a technology where the intensity of the LEDs are kept constant but the brightness adjustment is achieved by varying a time interval of flashing these constant light intensity light sources, the backlight is dimmed to the brightest color that appears on the screen while simultaneously boosting the LCD contrast