[Insight-developers] DICOM & JPEG update : Tcon topic

[Luis Ibanez]

Here is a suggested topic for friday's tcon.

Among the limitation of the current DICOM classes
in ITK we have the following:

   1) Do not manage JPEG compressed images.
   2) Do not provide writing.

In order to deal with (2), Mathieu Malaterre
contributed ImageIO classes for interfacing
with gdcm, an open source library developed
by the Creatis team at INSA-Lyon, France.

http://www.creatis.insa-lyon.fr/Public/Gdcm/

It will be convenient to add gdcm to the
Utilities directory and distribute it along
with ITK. The Creatis team has already updated
the license of gdcm in order to match the style
of the ITK license.

http://www.creatis.insa-lyon.fr/Public/Gdcm/License.html

-------------------------------------------------

Here are some of the issues involved:

The current source code of ITK takes 124 Mbytes.

The source code of gdcm takes 7 Mbytes.

4 Mbytes out of those 7 are for the JPEG libraries
that gdcm distributes in the same way that we
distribute jpeg, png, zlib in ITK's Utilities
subdirectory.

The current jpeg library in ITK takes 1.3Mbytes,
but has a number of limitations regarding the
functionalities of the JPEG standard.



The proposal is therfore to do the following:

1) replace the current jpeg libraries in ITK
    with the jpeg libraries used in gdcm.

    That is:  "ijg"   http://www.ijg.org/


2) Patch this library with a couple of known
    bug fixes.


3) Add gdcm to Insight/Utilities by removing
    its own distribution of jpeg, so there will
    be no duplication of jpeg code.



This process will require a number of adjustments,
but can probably be done in time for ITK release 2.0
in February 2005.




    Luis