Pioneer on Sunday said it is working on technology that will deliver plasma displays with black levels to deliver more effervescent colours.

Concept 50-inch Plasma displays being tested by Pioneer stop idle luminance in a TV, filling the screen will black levels that will allow the company's future plasma displays to offer a deeper spectrum of colours, said Russ Johnston, executive vice president of marketing and product planning.u

The announcement was made during a press conference at the Consumer Electronics Show being held in Las Vegas from January 7 to 10.

Contrast ratio of a display is measured by the ratio of the brightest light, which is white, to the darkest colour, which is black. In a pitch dark room, light emitted by a TV deteriorates image quality, diluting black and other colours, Johnston said. As the cells are black on Pioneer's concept plasma displays, it will dramatically reduce the measurement of the contrast ratio, Johnston said.

The higher the contrast ratio, the better a display performs, though there is some debate surrounding the measurement of contrast ratios. However, there is no debate that black is the more important colour on the display, Johnston said. As cells are black, the plasma TV seems invisible when entering a pitch-dark room, Johnston said.

Using what it calls "extreme contrast," the company incorporated new panels, filters and video processors in the 50-inch plasma screens to enable the technology, Johnston said. It is part of Project Kuro, which the company started two years ago.

Plasma TVs based on that concept won't be brought to market in 2008, Johnston said. Pioneer representatives declined comment on future plans.

The concept plasma displays also are small, measuring 9 millimeters (0.354 inches) in size, compared to current plasma displays, which are 3.5 inches (228 mm) thick, Pioneer said.