From DXOMark: More pixels offsets noise3

Started May 30, 2009 | Discussions thread
bobn2 Forum Pro • Posts: 61,111
Re: Bob..

Steen Bay wrote:

bobn2 wrote:

Steen Bay wrote:

Thanks. Reading Emil's reply again, I can see that he actually did
explain it nicely (and you too, of course), but still I find it a bit
counter-intuitive, that a gaussian blur affects the visible noise in
the downsampled image, but not the visible detail. Anyway, I'll take
your word for it, that it's the best method when downsampling, also
to prevent aliasing. (And it would of course be pretty easy to check,
downsampling the 50D resolution testchart shot, with and without the
gaussian blur)

Here you are 50D downsampled to 6.7MP, this time cubic, top no blur,
bottom blur.


Interesting, thanks. Isn't the top one, with no gaussian blur, the
sharpest, with most detail and noise? Does it have any
aliasing/artifacts? ISO 3200?

Could be I've overdone the blur a tad - if I got it right it shouldn't affect sharpness. Could well be aliasing in the top one, you'd need to hunt around the fabrics.
These are all ISO3200, same CR2's as PIX used.

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