OMD with more MP?

Started May 6, 2014 | Questions thread
Anders W Forum Pro • Posts: 21,468
Re: all your megapixels are fake

Great Bustard wrote:

Alex Notpro wrote:

Great Bustard wrote:

Alex Notpro wrote:

FYI all 16MP cameras use a Bayer CFA sensor, which means they're really 4MP interpolated to fake 16MP.

Actually, they're 16 MP monochrome pixels interpolated into 16 MP full color pixels.

OK but they're not even "full monochrome". Two thirds of the light and color information is discarded in each pixel. You need 4 of these partially blind monochrome pixels to make 1 real full color pixel.

This is true.

I'd like a real 16MP camera please.

It would be matched by a 32 MP sensor covered with a Bayer CFA and outperformed by a 64 MP sensor covered with a Bayer CFA.

You are probably right (based on your track record)...

Might wanna rethink that.

...but I find it counter-intuitive that the equivalence ratio would be 2x rather than 4x.

I'm not sure of the details, but I'm pretty sure it's because detail information comes primarily from the green channel, and there are two green filters in an RGGB CFA. Thus, the 2x factor between Bayer and Foveon is simply an average. If, for example, you were taking a pic of a scene that was dominated by a color far from green (for example, a tightly framed photo of a red rose), then it would be closed to 4x -- say 3x.

We are better at perceiving luminance than color detail, and luminance is primarily based on green, yes, for reasons explained here:

I would think that holds even if the object is strongly colored like your rose, when distinguishing bright from dark red.

Are you fully considering "information content" of each pixel? Is there an additional layer of information interpolation lurking in there?

There's spatial information and color information. From what I've seen, the 2x approximation for Bayer vs Foveon seems about right. For example, that means that the current 15 MP Foveon sensors should resolve as well, on average, as current 36 MP Bayer sensors, lens permitting, of course.

Should perhaps, but do they? Here are a set of crops from (aka Lenstip when translated to English) showing the 36 MP Bayer D800 versus all three 15 MP Foveon Sigma DP Merrills. The images were processed (by from RAW by means of DCRAW (no sharpening, no NR). The crops from the Merrills were upsampled (by me) in PSE 2.0 to roughly the same size as that from the D800. Does it really look like even-steven resolution-wise to you?

Note: Click on the image to view it properly.

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