DP Quattro: Sigma official announcement

Started Feb 10, 2014 | Discussions thread
webrunner5 Senior Member • Posts: 1,306
Re: Not exactly gone...

DMillier wrote:

Sorry, not sure I follow this. Let me speak aloud...

A simple monochrome sensor with say 20 million photosites arranged in a single layer will sample luminance only at 20 million locations and colour not at all. Result = true 20 MP mono image

A 20 million pixel Foveon X3 sensor would have 60 million photosites arrange in three layers such that it measures luminance and wavelength at 20 million spatial locations. Result = true 20MP full colour image.

A 20 million pixel Bayer sensor has 20 million photosites arranged in a single layer with filters over the photosites such that 10 million measure green channel, 5 million red channel and 5 million blue channel. None of these photosites are arranged at the same spatial location, so it is not possible to directly measure colour at a particular location. Instead the information about the wavelength and brightness of the light at each photosite has to be used to algorithmically compute the colour at 20 million spatial locations from information gathered from nearby locations. Effectively, spatial resolution is given up in order to work out colour. Result = < 20MP of full colour resolution.

The quattro chip has 20 million photosites arrange unequally in three layers 20 + 5 + 5. How are these photosites used and what does this mean for spatial and colour resolution compared to old Foveon X3 and Bayer CFA approaches?

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The web site is claiming Color Photo Detectors Total Pixels: Approx.33MP, Effective Pixels: Approx.29MP

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