Why 21mp is way better than 12mp

Started Oct 23, 2008 | Discussions thread
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Duane DeSieno Regular Member • Posts: 483
Why 21mp is way better than 12mp

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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