PowerShot SX230 HS bad pixels - RAW Shooting and Processing - CHDK Forum
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PowerShot SX230 HS bad pixels

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Offline curlyhead

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PowerShot SX230 HS bad pixels
« on: 06 / March / 2012, 15:36:08 »
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Hi,

I couldn't find anything about this already on the forum. I've been trying to shoot raw using my SX230 HS, firmware version 1.01a. I've managed to get .dng files, which I'm delighted with, except they have huge numbers of bad pixels.

If I zoom in on any part of an image I can see loads of little groups of 5-10 pixels that are usually blue, cyan, magenta or black but can be other colours too. These are not present on the corresponding .jpg files and I'm wondering what I have to do to get rid of them.

Obviously I have created the badpixel.bin file as it is necessary for shooting DNGs. I read in the user guide that I should also create a file called badpixel. I tried to do this using the show_bad program but it didn't recognise the raw file that I gave it.

Has anybody else had this problem?

Thanks a million in advance,
Curly
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Offline pjstout

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Re: PowerShot SX230 HS bad pixels
« Reply #1 on: 20 / April / 2014, 03:19:49 »
OK I am having the exact same problem is there a fix for this??
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Offline blackhole

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Re: PowerShot SX230 HS bad pixels
« Reply #2 on: 20 / April / 2014, 08:43:44 »
In the RAW menu, you must select a DNG version 1.1
DNG 1.3 works only with Adobe products and do not use badpixel.bin file.
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Offline reyalp

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Re: PowerShot SX230 HS bad pixels
« Reply #3 on: 20 / April / 2014, 20:37:44 »
Note that some cameras do not have enough free memory to operate reliably when DNG 1.1 is selected.

In raw therapee, the "hot/dead pixel filter" can give pretty good results with DNG 1.3. It doesn't seem to handle more than 1 bad pixel together though, which is common on some cameras.

While it's not very user friendly, you can also use chdkptp to fix badpixels in version 1.3 DNGs, or generate badpixels lists for use with other programs. I've added some documentation here https://www.assembla.com/spaces/chdkptp/wiki/DNG_Processing
« Last Edit: 20 / April / 2014, 22:01:55 by reyalp »
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Offline El Pistoffo

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Re: PowerShot SX230 HS bad pixels
« Reply #4 on: 12 / June / 2014, 16:58:43 »
I've had no luck creating a bad pixel file with my ELPH 300HS.  In camera creation fails and every PC based  bad pixel app I've tried fails to load my DNG or CRW dark frame pics.

On a side note, is there software to batch process dark frame subtraction on a bunch of RAW images (hundreds) and output to RAW?  No stacking of images.
« Last Edit: 12 / June / 2014, 17:08:12 by El Pistoffo »
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Offline reyalp

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Re: PowerShot SX230 HS bad pixels
« Reply #5 on: 15 / June / 2014, 20:48:30 »
Quote from: El Pistoffo on 12 / June / 2014, 16:58:43
I've had no luck creating a bad pixel file with my ELPH 300HS.  In camera creation fails and every PC based  bad pixel app I've tried fails to load my DNG or CRW dark frame pics.
If you shoot DNG 1.3, do the files contain an image, or do some (or all) of them contain random garbage?

Many recent cameras have trouble saving valid raw in AUTO mode. If you haven't already, try generating the badpixel file in P mode.

Quote
On a side note, is there software to batch process dark frame subtraction on a bunch of RAW images (hundreds) and output to RAW?  No stacking of images.
Generally, you wouldn't modify the raw, you would use it when producing some other file. Raw therapee can use dark frames in a batch, but the output would be a jpeg, png or tiff, not another raw.
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