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Exif in RAW mode

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Offline LjL

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Re: Exif in RAW mode
« Reply #10 on: 10 / July / 2008, 08:53:11 »
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Excuse me, but, do we really need to extract the EXIF information from the JPEG?
Can't we create them all ourselves using CHDK-provided functions?

I see the following EXIF (and/or other) information in Windows:
* width and height - shouldn't even be needed, but procase 24 (DIGIC II) or 218 (III) should provide it
* horizontal and vertical resolution - I think it's pretty arbitrary somehow (I'm always seeing 180 dpi), but it can be calculated if desired
* bit depth - I doubt it would be anything but 24
* frames count - uh, one...?
* brand - Canon, I guess
* model - I can't see a function to obtain it in CHDK, but it can certainly be added, since you build for a specific model
* color representation - sRGB, I guess
* shutter speed - some platforms provide a shooting_get_tv_str() function; it should be ported to all
* aperture - same, shooting_get_av_str()
* flash mode - seems to always be empty for me, but there is shooting_get_flash_mode() if that's what the tag is intended to contain
* focal distance - either get_focal_length(lens_get_zoom_point()) or get_effective_focal_length(something)
* F-number - seems to be the same as "aperture"
* exposure - is shutter speed, but can differ slightly from the "shutter speed" tag (1/202s vs 1/200s for instance; "exposure" seems to be the one that's actually shown in the camera when shooting, perhaps "shutter speed" is really the accurate one)
* ISO speed - shooting_get_iso_str() should be extended to all architectures
* "adjustment mode" - seems to always/often be "pattern" here (not sure how to translate and what is meant here, should check with an English system)
* exposure compensation - propcase 207 in DIGIC III, not sure about DIGIC II
* date - trivial

And of course, this approach would have the advantage of saving the real parameters when using CHDK overrides (at least if we're careful what functions we use to get the data).
« Last Edit: 10 / July / 2008, 08:56:45 by LjL »

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Offline RaduP

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Re: Exif in RAW mode
« Reply #11 on: 11 / July / 2008, 16:15:37 »
That's a good point, I didn't know that all this information was avaliable.
I think the most important things are:
ISO, Aperture, Exposure time, Camera model, and that's pretty much it.

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Offline LjL

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Re: Exif in RAW mode
« Reply #12 on: 12 / July / 2008, 20:21:35 »
For anyone who cares - I'm working on this, although it will probably take some time.

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Offline fe50

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Re: Exif in RAW mode
« Reply #13 on: 13 / July / 2008, 08:06:00 »
Hi LjL,

i think it would be nice to write the data also in a text file corresponding to the JPEG/RAW file name (with an menu option to enable/disable this feature)...so for every photo we have a file with additional informations to it.
There could be stored informations like the CHDK settings used for the shot, the script used for it, the script settings...

If we have the base functionality for generating such a "CHDK photo data file" in the source code it can be easily used for further enhancements (e.g. pre-defined labels, for debug data/messages...).

The file's structure could be like an .ini file with sections, e.g. like
  [EXIF]
  Brand=
  ISO=
  ...
  [CHDK Settings]
  Build=
  ...

...human readable & easy to use for further processing...what do you think about this ?


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Offline LjL

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Re: Exif in RAW mode
« Reply #14 on: 13 / July / 2008, 08:09:17 »
I think I wouldn't really want that on my camera (and you most likely can provide the additional CHDK-specific information in EXIF itself), but it's easy to implement and having it as an option won't hurt anyone. It'll also help with my own debugging, so I'll do that.

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Offline fe50

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Re: Exif in RAW mode
« Reply #15 on: 13 / July / 2008, 08:36:38 »
I think I wouldn't really want that on my camera (and you most likely can provide the additional CHDK-specific information in EXIF itself), but it's easy to implement and having it as an option won't hurt anyone. It'll also help with my own debugging, so I'll do that.

GREAT  ::)

It'll be very helpful for me (perhaps for others, too) for panorama & HDR photos and for the documentation of big scripting sessions.

After a 4 hour trip "in the wild" with hundreds of pics on the card (picture groups for HDR, some freehand panorama-base pics, the resulting pics of 3 scripts with 4 different settings, some pics made for testing new features, a DoF stacking test series...) the whole mess can be transfered to the hard disc and can be classified later, no more hand written notes like "19:01 - script "xxx" with a=1, b=20 c=30"  :-X
...and i can write some small scripts to automate some steps, e.g. for renaming, for archiving...


Re: Exif in RAW mode
« Reply #16 on: 31 / July / 2008, 01:40:56 »
Just wanna chime in since I am looking into on-camera caption writing. Initially I was going to store the caption in the IPTC header, but it looks like I can do that with EXIF as well. Do you think we can add EXIF comment as a part of your library?

 

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