Hooking Functions - page 2 - General Discussion and Assistance - CHDK Forum  
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Hooking Functions

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Offline reyalp

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Re: Hooking Functions
« Reply #10 on: 01 / November / 2009, 15:20:43 »
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Quote from: barberofcivil on 01 / November / 2009, 12:11:45
However, the image size overrides have no effect, they remain at the 1200x1600 size.  I would like to see if it is possible or not to override this and use larger image sizes or if it's inherent to the whole mode itself.
I believe the high ISO mode on newer cameras is accomplished with something like pixel binning http://www.ccd.com/ccd103.html (how exactly they do this with a bayer pattern is unclear, but that's sure what it looks like)
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Offline barberofcivil

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Re: Hooking Functions
« Reply #11 on: 01 / November / 2009, 18:52:30 »
Quote from: RaduP on 01 / November / 2009, 12:53:53
On many cameras, ISO 1600 is not different in what the sensor gets than ISO 800. The only difference is that the camera is brightening it in software. So don't waste your time with ISO 3200, just shoot raw an adjust the exposure in your raw processing program.

It's not so much the ISO3200, it's the high speed capture.  In ISO 3200 mode it's something like 4fps, whereas in other modes it's much slower.  In ISO3200 mode, the image size is limited to M3 (1200x1600).  I would like to find out if I can harness the speed but use a full image size or if M3 size is part of the high speed function for some reason. As I said, the ISO speed is overridable (as well as aperture and shutter) however, trying to override the image size at the same point as the other overrides has no effect.  I wanted to see if I could find out where in the mode it sets the image size to use.
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Offline reyalp

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Re: Hooking Functions
« Reply #12 on: 01 / November / 2009, 19:01:40 »
I believe the high speed is a directly result of the lower resolution. That's why I assume it is something like binning, that reduces the resolution very early in the process.

Note that other lower resolution settings are generally not much faster than full size. Not coincidentally, their raws are full sized. If you set 640x480 in the menu, a CHDK raw is still full sensor resolution, and maximum shooting rate isn't dramatically faster than shooting at much higher res. AFAIK, some of the lower resolutions are actually slower on some cameras.
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Offline barberofcivil

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Re: Hooking Functions
« Reply #13 on: 01 / November / 2009, 20:27:29 »
Quote from: reyalp on 01 / November / 2009, 19:01:40
I believe the high speed is a directly result of the lower resolution. That's why I assume it is something like binning, that reduces the resolution very early in the process.

Note that other lower resolution settings are generally not much faster than full size. Not coincidentally, their raws are full sized. If you set 640x480 in the menu, a CHDK raw is still full sensor resolution, and maximum shooting rate isn't dramatically faster than shooting at much higher res. AFAIK, some of the lower resolutions are actually slower on some cameras.
Reading about it, that seems likely.  Was hoping that there was some potential to add a bit of speed to larger images, at least CHDK allows the other overrides to work, I'm just stuck with smaller images for now.
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Offline RaduP

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Re: Hooking Functions
« Reply #14 on: 01 / November / 2009, 20:35:23 »
Keep in mind that pixel binning on most sensors will dramatically degrade the quality. In theory, it sounds all good, but in practice there are issues with it.
So a pixel binned photo will not look as good as a downsampled full sensor photo.
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Offline reyalp

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Re: Hooking Functions
« Reply #15 on: 01 / November / 2009, 21:11:25 »
Quote from: barberofcivil on 01 / November / 2009, 20:27:29
Reading about it, that seems likely.  Was hoping that there was some potential to add a bit of speed to larger images, at least CHDK allows the other overrides to work, I'm just stuck with smaller images for now.
Shot to shot delay is a major point of comparison in reviews. If canon could dramatically decrease decrease it, on their existing hardware, without loss of quality, they would.

Even if you buy the idea that canon deliberately cripples their low end cameras performance in software (which isn't really born out by the evidence) they wouldn't do it on their mid to upper segment cameras like the SX10.
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Offline yvesson

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Re: Hooking Functions
« Reply #16 on: 02 / November / 2009, 05:50:29 »
Hej,
Yeah I don't think it can happen in that department.
The limited fastest shutter speeds is something I don't get, it is limited deliberatly by canon (like 1/1250s at F2.6 on our A540, can't see a reason to not be able to use 1/2000s).

Morevover they explain the lack of HD video with the speed of the sensor, not only canon, so I guess original burst mode is just the best one can have out of the cam for the same reason.
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Offline fe50

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Re: Hooking Functions
« Reply #17 on: 02 / November / 2009, 07:33:09 »
FWIW - on the SX10 the RAW buffer size in ISO3200 mode is much lower...

Quote from: ewavr on 24 / March / 2009, 06:11:57
Quote from: emmanuel on 24 / March / 2009, 02:51:31
However the very strong iso3200 noise reduction appears to be applied anyway, which gives a picture almost as bad as real iso3200. am i doing something wrong?

BTW, RAW resolution in ISO3200 mode is only 1248x938 (1.1MP), but it still 12-bit  :D.

Maybe Canon's 1600x1200 is interpolated.
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