DCMTK reader fails for valid files

[pieper]

Description

Valid dicom files are rejected.

Steps to Reproduce

Use the itkDCMTKImageIO to read a file that has a dicom preamble and it is incorrectly rejected.

Expected behavior

File should be accepted.

Actual behavior

The readNoPreambleDicom implements a heuristic to see if the file starts with valid group/element tags.

https://github.com/InsightSoftwareConsortium/ITK/blame/master/Modules/IO/DCMTK/src/itkDCMTKImageIO.cxx#L231

But it fails when there is a preamble (which is often the case) there are 128 bytes and then the letters DICM.

https://dicom.nema.org/medical/dicom/current/output/html/part10.html#chapter_7

Reproducibility

Always

Versions

It appears to have been introduced by this commit:

19fa58f

Environment

All platforms.

Additional Information

I have a fix and will submit a PR.