Converting CHDK EXIF info to Standard EXIF - page 3 - General Discussion and Assistance - CHDK Forum

Converting CHDK EXIF info to Standard EXIF

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Offline whim

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Re: Converting CHDK EXIF info to Standard EXIF
« Reply #20 on: 04 / April / 2008, 12:20:37 »
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@Barney
@Fudgey

Quote
Originally I was hoping I could make a utility that would not only correct all ISO fields, but also allow other features. Like a quick FAT16/32 format SD card choice, Make SD Bootable, Format with CHDK Backup (it would read all CHDK folders, save them, format the SD card, and put your CHDK back like it should be).

Like a little CHDK Swiss-Army knife utlity

As I'm almost done adding Card functions (formatting, making bootable, udumper, etc) to my
Windows compiler shell, and it is programmed in AutoIt, I'm willing to add Exif-moving functionality,
which might move it a bit towards that. I'm open to suggestions...

wim

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Offline PhyrePhoX

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Re: Converting CHDK EXIF info to Standard EXIF
« Reply #21 on: 04 / April / 2008, 12:34:21 »
Quote
I'm open to suggestions...
...uhm, maybe release a linux build? :D

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Offline whim

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Re: Converting CHDK EXIF info to Standard EXIF
« Reply #22 on: 04 / April / 2008, 12:41:14 »
@PhyrePhox

I'm not sure if it goes for all AutoIt progs, but I do remember reading on their forum
that it's possible to run them under Wine ...
Don't know if you're using that, but if so maybe you could give it a try ?

wim

Re: Converting CHDK EXIF info to Standard EXIF
« Reply #23 on: 04 / April / 2008, 14:19:48 »
Deleted
« Last Edit: 22 / April / 2008, 08:28:50 by Barney Fife »
[acseven/admin commented out: please refrain from more direct offensive language to any user. FW complaints to me] I felt it imperative to withdraw my TOTAL participation. Nobody has my permission, nor the right, to reinstate MY posts. Make-do with my quoted text in others' replies only. Bye


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Offline fudgey

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Re: Converting CHDK EXIF info to Standard EXIF
« Reply #24 on: 05 / April / 2008, 12:03:27 »
I think I'm slowly starting to get the hang of all these tags, but please correct me if I'm wrong in anything :)

Barney's program overwrites some standard EXIF tag contents by values from Canon's MakerNotes data using the exiftool utility. There several good reasons to do this:

1) The standard EXIF tag values will be incorrect if CHDK has overrided ISO/Tv/Av. They show whatever would have happened if CHDK hadn't changed things instead of the real values.

2) The standard EXIF tag values are nicely rounded, "market values" everyone has gotten used to seeing in their camera's menus and photography in general (such as ISO 80 or Tv 1/60 s), while the real values may be for example ISO 75 and Tv 1/72. This means the values written to standard EXIF locations by Canon are often slightly inaccurate even when CHDK isn't running.

3) For many Canon camera models, the EXIF:ISO value may be useless if you shoot in Auto ISO mode, because it contains "Auto" instead of the ISO value chosen by the camera. This doesn't seem to be true for my A570IS, but I'm guessing it is  for other models because otherwise there wouldn't be utilities to fix EXIF:ISO...?

There's one thing I think should be looked at in Barney's program: It's mildly destructive. I mean, (if I'm not mistaken), the EXIF tags originally show the market values and whether an automatic ISO mode was enabled. That information is lost forever. I think it would be nice to know that I should set the camera to Tv 1/60 to repeat the shot later and that I used Auto ISO mode.

I was thinking the MakerNotes:CameraISO/FNumber/ExposureTime fields could be used to store what was deleted from the standard EXIF tags (effectively swapping stuff from EXIF to MakerNotes and vice versa), but then figured that running the program twice on the same file would screw things up majorly.

One solution would be to just write these to the UserComment field, so that it would read something like "SubjectDistance 0.432 m, CanonISO Auto, CanonTv 1/60 s, CanonAv 1/2.6"

Also, I think composite:iso shouldn't be written to MakerNotes:CameraISO unless it's really necessary.

If I'm not mistaken, for my A570IS

- EXIF:ISO contains Canon's "market" ISO value (chosen from menus or selected by Auto ISO mode) and is incorrect if CHDK overrides have been used and for some ISO settings it's also slightly inaccurate as it's a rounded "standard" value,
- MakerNotes:CameraISO contains the name of the camera ISO setting (such as Auto or 200), and
- composite:iso is a value calculated by exiftool from the Canon MakerNotes values CameraISO, BaseISO and AutoISO.
It is an accurate ISO value which we can trust unless the camera isn't capable of the overrided value set using CHDK.

Similarly, MakerNotes:FNumber is the real aperture value and EXIF:FNumber is a market value and the same goes for MakerNotes:ExposureTime and EXIF:ExposureTime.

I think the above is the same whether CHDK was running or not at the time of shooting (for example an old pic shot at Auto ISO without CHDK gets me composite iso of 75).

Is this not true for the S3IS or other models? I mean, I got the impression that Canon didn't use EXIF:ISO at all, but I think my camera does? Not that this matters much, since CHDK overrides make tag manipulation necessary.

If other models have different usage of the tags, maybe they need to be treated differently (the model can be tested from exif:model)?


Re: Converting CHDK EXIF info to Standard EXIF
« Reply #25 on: 05 / April / 2008, 17:00:25 »
Deleted
« Last Edit: 22 / April / 2008, 08:29:26 by Barney Fife »
[acseven/admin commented out: please refrain from more direct offensive language to any user. FW complaints to me] I felt it imperative to withdraw my TOTAL participation. Nobody has my permission, nor the right, to reinstate MY posts. Make-do with my quoted text in others' replies only. Bye

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Offline fudgey

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Re: Converting CHDK EXIF info to Standard EXIF
« Reply #26 on: 06 / April / 2008, 17:07:15 »
Thanks Barney. Apparently there can't be a single correct way to manipulate EXIF from our cameras, whether we run CHDK or not. People just have to check how things work with the applications they need their tags to be correct and manipulate EXIF accordingly.

Here's the sh script I came up with. It's probably not much use for Windows users unless you use a cygwin sort of an environment and get perl and exiftool to run properly under it.

It first backs up EXIF:ISO, EXIF:ExposureTime, EXIF:FNumber to the EXIF:UserComment tag along with MakerNotes:FocusDistanceUpper. If even one of these four tags does not exist, OR if the UserComment tag is not empty, OR if EXIF:Make tag is not "Canon", the script will skip the file totally because it thinks the file has either already been processed or that it is incompatible.

It doesn't overwrite any MakerNotes tags. So if there is some application that is being smart and digs the ISO for your Canon camera from MakerNotes instead of EXIF:ISO, it may possibly find an incorrect ISO if you overrided it with CHDK. I'm not quite sure about this, though.

See the script for details.

A standard disclaimer obviously applies, don't blame me if using it turns your dog purple. I would like to be informed if that happens, though :haha



Re: Converting CHDK EXIF info to Standard EXIF
« Reply #27 on: 07 / April / 2008, 01:33:52 »
Deleted
« Last Edit: 22 / April / 2008, 08:29:51 by Barney Fife »
[acseven/admin commented out: please refrain from more direct offensive language to any user. FW complaints to me] I felt it imperative to withdraw my TOTAL participation. Nobody has my permission, nor the right, to reinstate MY posts. Make-do with my quoted text in others' replies only. Bye


Re: Converting CHDK EXIF info to Standard EXIF
« Reply #28 on: 17 / May / 2008, 14:37:48 »
Rats!  I discovered this thread by following a link from the FAQ - CHDK Wiki, where it indicated that I could find the "Auto CHDK to EXIF v1.2.zip" file.  This discussion ran from December 2007 to April 2008, at which point apparently "Barney Fife" (the apparent creator of the program) took umbrage at some editing and removed all his posts. 

This means that all we see is talk ABOUT the program, but we have no way to reach the program itself, let alone "Barney"s extensive remarks about its use.

Where can it be found, and are there any extant usage instructions for it?  Could the CHDK wiki be updated to point to a more persistent location?

Thanks!

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Offline fbalb

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Re: Converting CHDK EXIF info to Standard EXIF
« Reply #29 on: 18 / May / 2008, 08:15:23 »
I'm also looking for "Auto CHDK to EXIF v1.2.zip"

I've found another program ExifAuto  but not test completly yet
ExifAuto
Thanks a lot all devellopers

 

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