[ImageJ-devel] Accessing metadata from C

[Curtis Rueden]

Hi Luc,

> I cannot figure out how to access metadata('Info') in a TIFF file,
> without launching ImageJ in batch mode to call getMetadata('Info')
> ...
>
> Is it possible with FreeImage or any other C library ?..

The metadata text is written out to the TIFF using custom tags 50838 and
50839.

Using libtiff's tiffinfo command line tool, you'll see something like:

  Tag 50839:
73,74,73,74,105,110,102,111,0,0,0,1,0,72,0,101,0,108,0,108,0,111,0,32,0,119,0,111,0,114,0,108,0,100,0,46,0,46,0,46,0,10,0,71,0,114,0,101,0,97,0,116,0,46

Which must then be decoded to a string.

Source code at:
https://github.com/fiji/ImageJA/blob/v1.48e/src/main/java/ij/io/TiffEncoder.java#L355
https://github.com/fiji/ImageJA/blob/v1.48e/src/main/java/ij/io/TiffDecoder.java#L43

Regards,
Curtis

P.S. Looks like someone submitted a patch to support this in Pillow, but it
is not yet merged:
https://github.com/python-imaging/Pillow/issues/291. Who knows what other
software already supports it.


On Tue, Oct 22, 2013 at 10:30 AM, Luc Deschenaux <luc at miprosoft.com> wrote:

> Hi,
>
> I cannot figure out how to access metadata('Info') in a TIFF file, without
> launching ImageJ in batch mode to call getMetadata('Info') ...
>
> Is it possible with FreeImage or any other C library ?..
>
> Regards,
>
> Luc
>
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