Archived posting to the Leica Users Group, 2004/07/01

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Subject: [Leica] Fungus in camera
From: abridge at gmail.com (Adam Bridge)
Date: Thu Jul 1 23:36:36 2004
References: <3.0.6.32.20040701084902.007d8810@pop.mail.yahoo.ca>

It seems very odd to me that Leica is trying to eliminate the
anit-aliasing filter. I distinctly remember my digital signal
processing courses that state that before you sample an analog signal
you have to limit the bandwidth with a filter to at least half the
sampling frequence (and that would be if you had a perfect low-pass
filter, you have to go lower for real-world filters.) Moire patterns
would be the result because artifacts would be generated by digital
sampling. I had a real-world example of this where we were measuring
ion-acoustic waves in very low-density argon plasmas and got results
that were really exciting - until the experimentalist realized he
hadn't built-in the low-pass filter. When the filter was installed the
"exciting" results vanished and things approached theory. Oh darn. But
that wasn't with optical systems and maybe someone who's won the
galactic institude prize for extreme cleverness has figured out how to
avoid the artifacts.

I sorta hope so....but I'm wary of free lunches.

Adam

On Thu, 01 Jul 2004 08:49:02 -0400, Dan C <bladman99@yahoo.ca> wrote:
> The other article concerns the digital back for the R8/R9.  They are aiming
> for a December launch, but they seem to be having problems getting the
> internal image processing software ready.  Leica isn't happy with it.   An
> "anti-aliasing" filter isn't be used, and they appear to be having problems
> solving the resultand moir? patterns visible is some images.   But they are
> also confident these problems will be solved.   No sample images yet.
> 
> -dan c.


Replies: Reply from dorysrus at mindspring.com (Don Dory) ([Leica] Fungus now filters)
In reply to: Message from bladman99 at yahoo.ca (Dan C) ([Leica] Fungus in camera)