At 3:05 PM +0000 9/22/03, olympus-digest wrote:
>Date: Mon, 22 Sep 2003 21:26:43 +0800
>From: "C.H.Ling" <chling@xxxxxxxxxxxxx>
>Subject: Re: [OM] New E-1 (noise reduction)
>
>I think you have missed the point, it was talking about compare camera noise
>of different camera especially by checking the data on the DC test web site.
>Since all DC process data differently it is hard to make a direct
>comparision by the standard deviation data posted. Some camera is very
>agressive in sharpening like C5050 and some are not like S1/2 Pro if the
>tests were performed at the camera's "normal" setting it won't tell too
>much.
Oh. About the stuff on the DC test web site, I have no opinion, not having
looked there. From your comments, they don't appear to be using the approach I
described, but I'll look. What's the URL?
>- ----- Original Message -----
>From: "Joe Gwinn" <joegwinn@xxxxxxxxxxx>
>
> >
> > I don't think it's impossible to test such cameras, even if the internal
>raw A/D counts are not available. One test occurs to me right off: With
>camera on a tripod, take multiple picutures of the same scene. Align the
>images (if needed) and subtract them, pixel by pixel. What's left is twice
>the noise power in the individual images. Do this with a collection of
>scene types, including ones with large flat areas. This is a classic
>black-box test, is directly relevant to practical use, and cannot be evaded,
>no matter what the camera manufacturer does.
> >
[snip]
One can always apply this kind of test. If the camera uses aggressive
sharpening, the test will show lots of noise (because sharpening emphasizes
high frequencies, such as white noise), but this is correct, as one will see
that same increased noise in one's photos. So, even if the DC test site tests
are not quite right, there are tests that do work.
Joe Gwinn
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