DICOM Encoded Image Profile - Brief Proposal
1. Proposed Workitem: DICOM Encoded Image Profile
- Proposal Editor: Don Mimlitch (GE?)
- Domain: Radiology and Cardiology
2. The Problem
DICOM permits image objects with encoded pixel data (e.g. as JPEG baseline, JPEG extended, JPEG 2000, RLE).
Such images are sometimes not properly displayed/processed by the receiving Actor due to poorly formed encoding, color spaces or bit-depths not supported by the Display, etc.
3. Key Use Case
An Ultrasound Modality sends a YBR Image with RLE encoding to an Image Manager/Image Archive.
An Image Display does a DICOM Image Retrieve requesting the Image as Unencoded (i.e. Uncompressed)
The Image Archive sends the Image to the Display as Uncompressed YBR since conversion of YBR to RGB is a lossy algorithm and this conversion is not allowed by the DICOM Standard.
The Image Display displays the image as if it were RGB which looks very wrong.
The Image Archive might have a Configuration Parameter to force the conversion to RGB but such conversion violates the DICOM Standard.
4. Standards & Systems
- DICOM Standard Part 5.
- RLE Definition
- JPEG Standard.
- JPEG 2000 Standard.
5. Discussion
An IHE Profile could help resolve the problem by:
- promoting cross-testing of DICOM compliance at Connectathon
The proposed profile will probably have one Required Encoding (JPEG Baseline) and the other Transfer Syntaxes will be Options. It might be better to require both JPEG Baseline and JPEG 2000 Lossy to make the Profile more applicable to modern Encodings.
Some problems we have seen in image Encoding/Decoding or Display are:
- JPEG or JPEG 2000 Images encoded with JFIF headers which the DICOM Standard does not permit.
- Images sent to a Display in Planar format and the Display displays it as if it were Interleaved.
- Images Encoded without the required Segment Table and Image Separators.
- Displays which do not handle the Bit Depth of a Negotiated Transfer Syntaxes. Such as RLE 16-bit Images or JPEG Lossless 12-Bit Images.