[Insight-users] Tiff Tag Warning on image load

[Luis Ibanez]

Hi Michael,

I'm browsing through the TIFF code looking
for a place where such a callback could be
inserted.

So, far I have not found a clear place where
this could be done, but there are many hints
that lead to think that it is indeed possible to
do it.

Let me list what I have found so far, in the
hope that other people can follow the trail
or find additional hits.

---

Here are some functions and variables in
the TIFF library that seem to be related to
a potential management of custom tags:


A) tif->tif_nfields :  number of known tags

if we could insert the id of that custom tag
in the structure for which nfields counts,
then it could be accepted during the initial
parsing in line 283 of tif_dirread.c


B) TIFFTagValue: struct in tif_dir.c

   In particular, its appearances in lines
   526-543 give us some hope:

   namely:

             /*
             * Grow the custom list if the entry was not found.
             */
            if( tv == NULL )
            {
    TIFFTagValue  *new_customValues;

    td->td_customValueCount++;
    new_customValues = (TIFFTagValue *)
      _TIFFrealloc(td->td_customValues,
             sizeof(TIFFTagValue) * td->td_customValueCount);
    if (!new_customValues) {
      TIFFError(module,
    "%s: Failed to allocate space for list of custom values",
          tif->tif_name);
      status = 0;
      goto end;
    }


-----


Once we figure out how to do this at the
level of the TIFF library, we will be able
to expose that functionality at the level
of the TIFFImageIO class.


    Regards,


          Luis



----------------------------------------------------------
On Thu, Sep 30, 2010 at 2:07 PM, Michael Jackson <
mike.jackson at bluequartz.net> wrote:

> I get the following warning when I open some of my Tiff files:
>
> TIFFReadDirectory: Warning, 7001.tif: unknown field with tag 34681 (0x8779)
> encountered.
>
> I know what the field is and I know how to parse it. Are there any
> facilities for setting a callback function or anything like that to the Tiff
> file reader?
>
> Thanks
> ___________________________________________________________
> Mike Jackson                      www.bluequartz.net
> Principal Software Engineer       mike.jackson at bluequartz.net
> BlueQuartz Software               Dayton, Ohio
>
>
>
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