The Moto X’ Clear Pixel camera could feature a RGBW sensor

July 9, 2013
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The upcoming Moto X is rumored to feature a Clear Pixel camera that would supposedly allow for better pictures in low light conditions. The description fits one technology in particular – RGBW sensors.

Moto X ad

According to Taylor Wimberley, the founder of Android and Me and a person that leaked stuff from Google’s kitchen before, the upcoming Moto X will feature a Clear Pixel camera. Wimberley revealed the info on Google Plus, and, when asked what Clear Pixel actually is, he said “It means ‘dark, blurry pics and lack of details’ will be things of the past…”

That certainly sounds exciting. Low light photography has always been the Achilles’ heel of smartphone cameras, a weakness that HTC tried to mitigate on the One by making pixels larger, so they capture more light. But UltraPixels have the drawback of being… well, large, which means HTC was only able to equip the One with a 4MP (or UP, if you prefer) sensor. In other words, the Taiwanese company sacrificed detail for low-light performance.

So, how could Motorola deliver better low-light performance without making pixels larger? The solution may be, according to Brian Klug of AnandTech, a RGBW sensor.

Let’s back up a little. Regular smartphone camera sensors use a RGB (red, green, blue) filter to form the digital image. Each pixel on the sensor is covered by an array of red, green, and blue “specks”, for lack of a better term. Each speck lets only light of certain wavelengths pass through and reach the pixel. Using an algorithm, the imaging chip then converts the light intensity and wavelength from each pixel into a color, and then all the pixels are put together to form the final digital image.

The problem is that some of the light is lost when it passes through the colored RGB filters, which isn’t an issue in bright light, but causes blurry, noisy images when light is insufficient.

To solve this problem, Eastman Kodak created a RGBW filter, which is similar to RGB, but also includes white specks in the filter pattern. The white specks let through light of all wavelengths, as opposed to colored filters, which ignore much of the light that hits them. As a result, RGBW sensors fare much better in low-light, because the white filters let them make the most of the available light.

Sony RGBW

Sony RGBW sensor demo

Last year, Sony announced that it planned to include an RGBW filter in the Exmor RS sensor that equips devices like the Xperia Z. However, in autumn Sony cancelled the RGBW sensor because “it was found not to meet certain conditions of Sony’s image quality standards”. In other words, they couldn’t get the technology to work in time to ship in Exmor RS.

Will the Moto X come with a Sony-made RGBW sensor? We can only speculate, but as Brian Klug (who is an optical engineer by formation) puts it, the description of Clear Pixel does sound a lot like RGBW.

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