Canon Line Offset Noise

Started Oct 20, 2009 | Discussions thread
OP John Sheehy Forum Pro • Posts: 22,810
Re: intreresting discussion but.....

FZ20_Alff wrote:

Hi John,

I hate to say it, but if your goal was to show how easily it could be for Canon to make this particular noise problem dissapear, then I would have to say you have not fully succeeded.

It's one thing to take a totally black test image and manipulate the noise within. It's quite another to take that knowledge and show how it would improve a real world example.

Right now as far as anyone knows your suggestion and technique was not adopted by Canon because it could ruin other qualities of the photo. There is no way to tell based on what has been presented so far.

Sorry.

The 7D is the hot topic camera, and the most recent, so that's why I used it. I don't have a 7D, and used someone else's blackframe. I haven't shown in this thread, but I have done this with real images with no negative aspects in the results. If one understands that the sensor is a linear capture device, they know that the intensity of the offsets is the same at all tonal levels. Don't forget, I am only subtracting offsets; nothing that has anything to do with signal. If one line is 0.7 ADU too high compared to it's neighbors, that is 0.7 vs 0, or 11,006.7 vs 11,006. Correcting by 0.7 ADU at 11,006 is insignificant, even if it is wrong. The only tonal levels at which the small corrections can have any effect if they are wrong, is near black.

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John

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