Disable Vignetting Correction For The SX230 HS?

SX720

« on: 12 / September / 2020, 13:37:23 »

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This thread here mentioned that Canon IXUS 300HS applies vignetting correction to the RAW data but I didn't see a solution to that. https://chdk.setepontos.com/index.php?topic=6725.msg118032#msg118032 The Canon SX230 HS is doing the same thing.

When zoomed out all the way the SX230 HS seems to be applying gain to the edges of the image. Is there a way to completely disable this behavior?

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reyalp

13844

Re: Disable Vignetting Correction For The SX230 HS?

« Reply #1 on: 12 / September / 2020, 23:19:33 »

There's some discussion of the vignetting correction stuff (and a lot of other things) in this thread: https://chdk.setepontos.com/index.php?topic=8801.450

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Don't forget what the H stands for.

SX720

Re: Disable Vignetting Correction For The SX230 HS?

« Reply #2 on: 13 / September / 2020, 18:03:35 »

Thank you for the link. It looks I need to look for shading in addition to vignetting. I don't understand how srsa_4c did it, but it's exactly what I hope to achieve. I'm talking about this specific post: https://chdk.setepontos.com/index.php?topic=8801.msg103438#msg103438

I wasn't able to figure out what to do with the 0209 and 0210 values. I'm also guessing that this will all be camera specific so I don't even know if those values will work for the SX230.

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srsa_4c

4450

Re: Disable Vignetting Correction For The SX230 HS?

« Reply #3 on: 14 / September / 2020, 16:19:18 »

Quote from: SX720 on 13 / September / 2020, 18:03:35

I wasn't able to figure out what to do with the 0209 and 0210 values.

Those are not values, just the names of those two images.

Quote

I'm also guessing that this will all be camera specific

Indeed. I think I lessened correction indirectly by faking tele zoom at a few parts of Canon's image processing code. It happened a long time ago, so I don't remember all details. It's possible there are better ways.

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