[Debian-med-packaging] Bug#988644: Defined Term: ISO 2022 IR 87 is not supported

[Mathieu Malaterre]

Hi Jörg,

On Mon, May 17, 2021 at 3:49 PM Jörg Riesmeier <debian at riesmeier.de> wrote:
>
> > Could you please clarify the following statement then:
> >
> > [...]
> > As far as I understand it ISO 2022 JP is also a set containing
> > multiple character sets that can be switched via escape sequences. The
> > ICU handles these escape sequences internally whereas the libiconv
> > doesn't. This is why the existing code in DCMTK that was orignally
> > written for libiconv parses these escape sequences itself, therefore,
> > the ICU does not perceive them and cannot chose the correct character
> > set. The only way to fix this would be to disable parsing the escape
> > sequences when the ICU is used and then set all character sets similar
> > to your proposition.
> > [...]
>
> I personally implemented support for the character set conversion based on
> libiconv into the DCMTK. So, the original implementation of the OFCharacterSet
> and DcmSpecifificCharacterSet classes were designed in a way that allowed for
> using libiconv for the various (i.e. all) specific character sets defined in the
> DICOM standard, i.e. including ISO 2022 switching of character sets.
>
> The ICU and stdlibc (iconv) support was added later by a colleague from the
> OFFIS institute based on this original implementation but, unfortunately,
> without adapting the parsing approach (e.g. searching for the escape sequences
> used for ISO 2022), so that when ICU support is enabled all DICOM character
> sets can be used in the same manner as before (also see comments in the
> respective DCMTK class).

Thanks for the clarification !

I've removed explicit usage of ICU, since support will be equivalent
when using stdlibc (iconv), with the added bonus that we remove a
dependency to ICU.

https://salsa.debian.org/med-team/dcmtk/-/commit/666129093bee6d907ef763324835209e4416ff10

and documentation has been added for Debian users:

https://salsa.debian.org/med-team/dcmtk/-/commit/a533a4acb57242e8c9e9f011e3ba083c8382da97

-M