Flat Field Correction

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Flat Field Correction

Postby NN8900311 » Wed Jan 11, 2012 7:55 am

I recently came across the following question and do not know the answer.

In reference to a setup consisting of a PhaseOne P30+, Mamiya 645 body, 80mm macro and CP1

Does your camera and/or Capture 1 have any sort of "flat field" correction to compensate for minor differences in the sensitivity of individual pixels?


Could anyone advise regarding an answer to the above question?

Thanks in advance :)
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Re: Flat Field Correction

Postby Drew » Wed Jan 11, 2012 9:56 am

Can you provide context for this question?
A "Flat Field Correction" exists to some degree (to the best of my knowledge) in every digital capture device. It is simply a way to reference the presence of a calibration to ensure uniform behavior in the chip so that one pixel reacts the same as another in response to analog input.
Drew
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Re: Flat Field Correction

Postby NN8900311 » Wed Jan 11, 2012 11:01 pm

Thanks Drew,

Your response answered my question:

The fellow who answered your question was on exactly the right track. As I wrote earlier, the radial streaking pattern in Dave's stack result looks like what one would get if the images had a little bit of pixel-to-pixel variation that is fixed in position rather than varying randomly from frame to frame like ordinary noise. This is what you'd see if the "calibration to ensure uniform behavior" had been done improperly or not at all. So what I'm wondering is if that calibration is exposed to the user and might have gotten turned off or messed up somehow.

We were attempting to troubleshoot a possible anomaly in a macro focus stacking exercise.


Another question:
So what I'm wondering is if that calibration is exposed to the user and might have gotten turned off or messed up somehow.

Is it possible for this 'calibration' to be turned off by the user or 'messed' up in some way, either via the digital back or CP1?

Craig
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Re: Flat Field Correction

Postby Drew » Thu Jan 12, 2012 10:11 am

NN8900311 wrote:Is it possible for this 'calibration' to be turned off by the user or 'messed' up in some way, either via the digital back or CP1


No, this is not possible. If the Calibration were not present, it would not be a subtle variation that would be overlooked, it would be quite clear. I would suggest that you create a support case and provide the files that are referenced in the anomaly so we can have a closer look and provide some more insight on what might be occurring.
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