Why 21mp is way better than 12mp

Started Oct 23, 2008 | Discussions thread
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Duane DeSieno
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Why 21mp is way better than 12mp
Oct 23, 2008

Always give me more pixels...
Well the conventional wisdom is more pixels equals more noise.
Now the 5DmkII has 21mp and no-one is saying it is noisier than the 12mp 5D.

So I ran this experiment. In photoshop make a 5616x3744 gray image and add 10% monochromatic gaussian noise and save the image. Then I used my SharpRaw to load that image and resize it to a 4386x2920(the 5D size I get converting a raw file) output jpg image. In resize options I set Subsample Mult to 5 so for each output pixel SharpRaw averages 25 interpolated samples to construct the output pixel. The resize takes some time since that is a lot of interpolating.

Reloading the now 12mp image I measured the standard deviation of a 51x51 patch of pixels. The results showed a 40.86% decrease in the noise...

original 5616x3744 image noise standard deviation 0.102840 (0-1.0 pixel values).
resized 4386x2920 image noise standard deviation 0.060822

So starting from a 21mp image and resizing to 12mp lowered the noise 40.86% but it also makes any raw interpolation artifacts smaller. I think that interpolation artifacts may be as important as noise.

Bottom line, I'll take more pixels any day. Then, if I want a clean High ISO image I can resize down and integrate out a lot of the noise.

So where is my 5DmkII!!!

Duane

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