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Dark Frame Subtraction

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Dark Frame Subtraction
« on: 07 / January / 2013, 10:11:07 »
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I notice on my S95 that the canon dark frame noise reduction (I assume it is this) can not be switched off, the following represents my observations:

* take a 15 sec canon RAW exposure and the camera sits there with a busy message for another 15 sec.
* take a 15 sec canon JPEG only and the same occurs, ie 15 + 15 sec

I have CHDK dark frame switched off, but this doesn't. Seem to do anything.

Can someone throw any light on this and whether the S95 dark frame taking, which I assume occurs on exposure over 1 sec, can be switched off fully.

I am interested in solving this as I take a lot of brackets and I would like to speed things up.

Cheers

Garry

Re: Dark Frame Subtraction
« Reply #1 on: 07 / January / 2013, 12:04:59 »
I have CHDK dark frame switched off, but this doesn't. Seem to do anything.

If so,  then that's a bug in the S95 port.   FWIW .. its usually better to post this sort of camera specific question directly in the porting thread for that camera.   
Ported :   A1200    SD940   G10    Powershot N    G16

Re: Dark Frame Subtraction
« Reply #2 on: 07 / January / 2013, 13:19:50 »
Sorry I didn't know there was such an area and can't seem to find it.

Cheers

Garry

Re: Dark Frame Subtraction
« Reply #3 on: 07 / January / 2013, 14:42:54 »
Sorry I didn't know there was such an area and can't seem to find it.

S95 Porting Thread

Looks like this has been noticed before :

http://chdk.setepontos.com/index.php?topic=5641.msg65735;topicseen#msg65735
Ported :   A1200    SD940   G10    Powershot N    G16


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Offline whim

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Re: Dark Frame Subtraction
« Reply #4 on: 07 / January / 2013, 15:05:55 »
@pigeonhill

Can you try with CHDK RAW (instead of CANON RAW) ? AFAIK this feature only works with CHDK RAW enabled.

wim

Re: Dark Frame Subtraction
« Reply #5 on: 07 / January / 2013, 15:16:36 »
Wim

I can confirm the I see the same whether I have Canon JPEG set with or without CHDK RAW enabled and with or without subtract enabled.

Cheers

Garry

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Offline philmoz

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Re: Dark Frame Subtraction
« Reply #6 on: 07 / January / 2013, 16:33:03 »
Sorry I didn't know there was such an area and can't seem to find it.

S95 Porting Thread

Looks like this has been noticed before :

http://chdk.setepontos.com/index.php?topic=5641.msg65735;topicseen#msg65735

The address used for 'nrflag' in capt_seq.c for the S95 does not match the address found by finsig_dryos (reported in stubs_entry.S). The sig finder also suggests that '#define NR_AUTO (0)' needs to be added to capt_seq.c for this camera.

If no-one beats me to it I'll build a test version tonight using the sig finder address.

Phil.
CHDK ports:
  sx30is (1.00c, 1.00h, 1.00l, 1.00n & 1.00p)
  g12 (1.00c, 1.00e, 1.00f & 1.00g)
  sx130is (1.01d & 1.01f)
  ixus310hs (1.00a & 1.01a)
  sx40hs (1.00d, 1.00g & 1.00i)
  g1x (1.00e, 1.00f & 1.00g)
  g5x (1.00c, 1.01a, 1.01b)

Re: Dark Frame Subtraction
« Reply #7 on: 07 / January / 2013, 17:44:45 »
AFAIK this feature only works with CHDK RAW enabled.
I'm pretty sure it that you can use this to disable dark frame for JPG's even if RAW is not enabled.

Update :  tested on my G10.  Works without RAW enabled to disable dark frame correct.
« Last Edit: 07 / January / 2013, 18:41:03 by waterwingz »
Ported :   A1200    SD940   G10    Powershot N    G16


Re: Dark Frame Subtraction
« Reply #8 on: 07 / January / 2013, 19:19:17 »
Also works on my G11..

As said by philmoz looks like the S95 code is broken.

Cheers

Garry

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Offline philmoz

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Re: Dark Frame Subtraction
« Reply #9 on: 08 / January / 2013, 02:48:36 »
CHDK ports:
  sx30is (1.00c, 1.00h, 1.00l, 1.00n & 1.00p)
  g12 (1.00c, 1.00e, 1.00f & 1.00g)
  sx130is (1.01d & 1.01f)
  ixus310hs (1.00a & 1.01a)
  sx40hs (1.00d, 1.00g & 1.00i)
  g1x (1.00e, 1.00f & 1.00g)
  g5x (1.00c, 1.01a, 1.01b)

 

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