For it to be effective, you need to make the dark frame for
subtraction in-camera as close to the time of exposure as possible in
order to obtain the sensor's state at that moment. Sensor state
varies as a function of temperature, power levels, electrical flux in
the camera, etc. Ideally, you'd want to take the dark frame at the
same moment as the actual exposure... which of course isn't possible.
The only benefit I can see obtaining from doing the dark frame
subtraction in post processing would be the ability to adjust the
subtraction algorithm.
Godfrey
On Jul 15, 2005, at 7:31 AM, Jostein wrote:
I've been wondering about the same, Bill. Haven't really pursued
the matter, but I suspect that there must be some software designed
for astrophoto that can do it.
Jostein
----- Original Message ----- From: "William Robb"
<[EMAIL PROTECTED]>
To: "Pentax Discuss" <[email protected]>
Sent: Friday, July 15, 2005 4:13 PM
Subject: Noise reduction
The lightning thread got me thinking.
In camera noise reduction is done by doing a dark field exposure,
and using that as a template for removing noise from the image
exposure.
I am wondering if anyone has tried doing this as an out of camera
operation?
If it were possible, it would remove one of the problems with in
camera noise reduction, which is the loss of camera functions
while noise reduction is being calculated.
William Robb
