Extracting binary exif chunk without thumbnail

[Archive]

[Originally posted by nafai on 2008-01-20 01:43:50-08]

I am considering using ExifTool for my own online photo gallery
(http://nafai.org/photos" target="_blank">http://nafai.org/photos), but I am missing one feature. I would like to
extract raw EXIF data (excluding the thumbnail) to a file and then later
use that as input when generating the tags to be displayed. Actually I
am planning to store the exif data in a database together with other image info.

I thought I could write like this:

Code:

ExifTool -Exif --ThumbnailImage -b DSCF0001.jpg > DSCF0001.exif

but that doesn't seem to work. Anyone have any ideas?

thanks

[Archive]

[Originally posted by bogdan on 2008-01-20 08:02:29-08]

If I understand correctly: you just wish to extract exif data into some external file, which can be later reused (for examining, writing back to image, etc.)?

If so, then I suggest you use MIE file:

exiftool -o exif.mie -exif:all --makernotes photo.jpg

-this will create exif.mie file, which will contain (only) all exif info from photo.jpg file. Think of mie file as being jpg (or any image file) without containing any image. So, you can read/edit mie using exiftool and even write it back into another image file.

Greetings,

Bogdan

[Archive]

[Originally posted by nafai on 2008-01-20 09:41:59-08]

Thank you very much for the reply! This was exactly what I was looking for.
I actually wanted to keep the makernote information in the output file so I just used it like this:

Code:

exiftool -o photo.mie -exif:all photo.jpg

All the information could then easily be extracted from the mie file again by simply writing:

Code:

exiftool photo.mie

The information was identical except for one field,

Code:

Y Cb Cr Positioning             : Co-sited

which became

Code:

Y Cb Cr Positioning             : Centered

when I ran ExifTool on the mie file. I wonder why.

[Archive]

[Originally posted by exiftool on 2008-01-20 15:10:16-08]

Thanks Bogdan.

The YCbCrPositioning tag is considered "unsafe" to copy because it
may affect the way the image is rendered.  These "unsafe" tags are
listed in the tag name documentation, and must be specified
explicitly if you want them copied.

YCbCrPositioning is unique in that as well as being "unsafe", it is
also a required tag according to the EXIF specification.  Currently
ExifTool sets this to "Centered" by default if not specified.  This is
why you get a different value for this tag.

Perhaps in a future release I will come up with a better way to
handle this.

- Phil