At 3:31 AM +0200 5/14/04, Listar wrote:
>From: Cyrtolite@xxxxxxx
>Date: Thu, 13 May 2004 20:20:35 EDT
>Subject: [OM] Re: Anomalies in E-1/OM Images -- Update
>
>
>Thanks for the reply, Wayne.
>You are seeing oshop's unsharp mask tool for the sharpening (500%,
>3 pixels radius, threshold anywhere from 0 to 10 levels). The spots are
>visible before sharpening and some of them are too large to be a sharpening
>artifact. Sharpening just makes some of them easier to see. I see
>no signs of dead
>pixels. I think they'd be pretty easy to see at 100-200%.
>
>I suppose clusters of dead pixels could be on the right scale but I would
>expect dead pixels to occur randomly (though differential heating or something
>like that could cause them to occur preferentially in a particular part of the
>sensor).
Columns of dead pixels are also common. It isn't totally random.
>The spots are about perfectly circular and the larger ones are
>composed of concentric rings. It's hard to imagine how this kind of
>symmetry could
>result from sharpening around random defects.
You are seeing dust on the glass cover of the sensor. The rings are
diffraction (airy) rings from the dust particles.
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