Mercurial > hg > orthanc-book
comparison Sphinx/source/developers/implementation-notes.rst @ 73:c742c8f9ffa3
encodings
| author | Sebastien Jodogne <s.jodogne@gmail.com> |
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| date | Wed, 14 Dec 2016 09:43:08 +0100 |
| parents | |
| children | a976607e46f7 |
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| 72:83c0a6556e6c | 73:c742c8f9ffa3 |
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| 1 .. _implementation-notes: | |
| 2 | |
| 3 Implementation notes | |
| 4 ==================== | |
| 5 | |
| 6 Encodings | |
| 7 --------- | |
| 8 | |
| 9 DICOM supports many codepages to encode strings. DICOM instances using | |
| 10 special characters should contain the ``SpecificCharacterSet | |
| 11 (0008,0005)`` tag. The latter tag `specifies which codepage | |
| 12 <http://dicom.nema.org/dicom/2013/output/chtml/part03/sect_C.12.html#sect_C.12.1.1.2>`__ | |
| 13 is used by the DICOM instance. Internally, Orthanc converts all these | |
| 14 codepages to the `UTF-8 encoding | |
| 15 <https://en.wikipedia.org/wiki/UTF-8>`__. | |
| 16 | |
| 17 In particular, :ref:`plugins <creating-plugins>` must assume that any | |
| 18 string or JSON file coming from the Orthanc core is encoded using | |
| 19 UTF-8. Similarly, plugins must use UTF-8 when calling services | |
| 20 provided by the Orthanc core. The conversion to/from UTF-8 is done | |
| 21 transparently by the plugin engine. | |
| 22 | |
| 23 The :ref:`configuration option <configuration>` ``DefaultEncoding`` | |
| 24 plays an important role. It is used in three cases: | |
| 25 | |
| 26 1. If receiving a DICOM instance without the ``SpecificCharacterSet | |
| 27 (0008,0005)`` tag, Orthanc will interpret strings within this | |
| 28 instance using this default encoding. This is important in | |
| 29 practice, as many DICOM modalities are not properly configured with | |
| 30 respect to encodings. | |
| 31 | |
| 32 2. When answering a :ref:`C-Find query <dicom-find>` (including for | |
| 33 worklists), Orthanc will use its default encoding. If one single | |
| 34 answer uses a different encoding, it will be transcoded. | |
| 35 | |
| 36 3. If creating a new instance (e.g. through the | |
| 37 ``/tools/create-dicom`` URI of the :ref:`REST API <rest>`, or | |
| 38 through the ``OrthancPluginCreateDicom()`` primitive of the plugin | |
| 39 SDK) and if ``SpecificCharacterSet (0008,0005)`` is not provided | |
| 40 for this instance, Orthanc will use its default encoding. Note | |
| 41 however that if ``SpecificCharacterSet`` is set, Orthanc will | |
| 42 transcode the incoming UTF-8 strings to the codepage specified in | |
| 43 this tag, and not to the default encoding. |