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Friday, March 23, 2012, 02:37 pm PT (05:37 pm ET)

Tech behind new iPad's color quality attributed to 30% increase in power usage

A study released on Thursday estimates that the technology used in the iPad's Retina Display consumes 20-30 percent more power to attain Apple's claimed 44 percent improvement in color saturation over the iPad 2.

According to results from a series of tests conducted by display-centric blog dot color, the new Retina Display iPad utilizes advanced filters to improve color reproduction, which forced Apple to bump the output of the tablet's backlight LEDs to maintain a brightness comparable to previous models.

A problem with all LCD displays is unwanted light leakage which translates to inaccurate color reproduction and lower saturation. To solve the problem and improve an LCD screen's range of color, or color gamut, display makers can either boost the performance of backlight LEDs or implement higher quality filters. In both cases the goal is to represent the primary colors, red, green and blue, as purely as possible since these three hues are mixed to create a display's color spectrum.

Based on the test's measurements, Apple chose to concentrate on upgrading the filters used in the Retina Display to more accurately reproduce the primary colors. The new technology resulted in a spike in power consumption, however, because the improved filters let less light through than inefficient versions. This is to be expected, as high quality filters are narrower by design in order to block out unwanted light bands.

The spectrum graph below was taken from a white screen on both the iPad 2 and third-generation iPad in which all primary color are switched on. Reading the results show that the Retina Display features a significant peak at the 450 nanometer wavelength without much change in shape, meaning that the brightness of the color blue has been boosted.

iPad 3 Color

Source| dot color


When the same spectrum measurements are taken with only blue sub-pixels open, the same peak can be seen, however there is also a slight bump at around 540 nanometers. This small peak means that iPad displays leaks a certain amount of green light when displaying "blue" colors.

iPad 3 Color 2

Source: dot color


What can be seen from this blue-pixel-only chart is that the new iPad allows less green light to pass through the filter which translates into a purer blue.

iPad 3 Color Blue

The iPad 2's display (left) shows a slightly aqua tinge when compared to the new iPad's Retina Display (right) | Source: dot color


As a result of the enhanced color, less light is getting through the improved filters and thus more LEDs or more powerful units are needed to compensate. By dot color estimates, this relates to a 20-30 percent increase in power consumption which is most likely one of the main reasons why the new iPad sports a massive 42.5-watt-hour battery.