Canon Line Offset Noise

Started Oct 20, 2009 | Discussions thread
JimH Forum Pro • Posts: 12,911
Re: The question I've got is...

John Sheehy wrote:

This could be automated to operate on batches of files (say, everything in a directory). So it'd be an easy thing to apply to all of our shots to remove this problem.

Yes, but it would be nice if the camera calibrated itself, and this was all done before the RAW is written. 14 bits should be enough for doing the necessary corrections, but a mediocre 16-bit ADC with 13 bits of real precision (3 for dither - better to use noisy bits in an ADC than to "add" dithering noise) should be sufficient for the calculations, without causing histogram shifts.

As far as the other main issue, gain, is concerned, the 7D is already compressing the original RAW histogram, so just changing the factors to equalize the channels would add no further problems.

I guess my main point here was that given what we do have from Canon right now, and given that nothing we say here seems to ever have any effect on their cameras, it would be nice to develop a little program that photographers could use to reduce the vertical banding (and maybe other problems as well).

The program could easily store different calibrations for different ISOs, and it wouldn't take much effort on the part of the photographer to shoot a group of black frames to "feed" into the program to get it calibrated for their camera.

The EXIF from the files could be read by the program so it'd recognize the serial number of the camera and the ISO. Perhaps some other parameters could be used, too (shutter speed?).

So a photographer could then pre-process his or her shots with this program to clean them up prior to feeding them into their favorite RAW converter.

Let's not think of Canon's apathy as a bad thing. Let's think of it as an opportunity. An opportunity for some clever programmers (ahem) to make some money off of it all

I'll bet that even the Canon apologists might be our customers here (wink wink, nudge nudge).

If it was set up to work for any Canon DSLR, and became a hugely popular program, selling very well, maybe that would get Canon's attention. Then again, maybe not!

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Jim H.

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