Megapixels

Hey,
when reading about Sigma cameras it says it's 15 MPx sensors are actually equivalent to 46 Mpx sensors as every pixel has 3 layers each being R, B or G.

So does this mean that for example the K3 sensor which uses classical Bayer with 24 MPx sensor creates an image that has less than 8 million "white" pixels? I'm saying below 8MPx as Bayer pattern has more G than R or B.

Cheers

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Pentax K-5 and co.

This is all highly debatable. A sensor such as used in the K-3 has 24 MP, but the sensor is overlaid by a pattern of coloured filters called a Bayer pattern. That's because sensors are black and white by nature. So, small groups of pixels are interpolated to "guess" the colour at each pixel. Then it's all assembled as a full colour image of 24MP.

The Foveon sensor has three layers, each sensitive to red, green and blue as in a colour film, stacked on top of each other with appropriate filters blocking different colours of light for the three layers. The argument is that therefore each pixel site has accurate RGB information so we can multiply the resolution by three. Also, that colour is more accurate as a result.

However, there's no visual evidence that this is actually so and personally I don't like the look of Foveon images.

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Best regards, John

wow, didn't know there is a colour filter over the sensor, always thought the light sensors were sensitive to a specific frequency of light.

So if the final image is 24 MP, then the amount of physical light sensors is somewhere around 72 million?

Cheers

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Pentax K-5 and co.

No, the final image is 24MP.

Not all those pixels are delivering all colours, it's extrapolated from those that are.

Wikipedia will have a picture that explains it I'm sure.

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Best regards, John

http://en.wikipedia.org/wiki/Bayer_filter

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Best regards, John

See here http://en.wikipedia.org/wiki/Bayer_filter for info.

That 24Mp (mono pixel) sensor eventually produces a 24Mp RGB image with the colour values being interpolated between pixel sites. So that 24Mp sensor is equivalent to anywhere between an 8Mp and 24Mp perfect RGB sensor depending on what you measure and its true performance probably lies somewhere in the middle of that range.

In reality the best thing to do is ignore the numbers and compare images from the Faveon and Bayer sensor and see which ones you prefer. The do tend to have different characteristics so it is more personal preference than technical merit one way or the other.

sorry John - didn't spot that you had posted the same link.