How to decompress DICOM data and convert Transfer Syntax

[Icron1]

Hello,

Thank you a lot for this great library.

I have a use case where I need to convert DICOM files that have compressed pixel data (e.g. JPEG, etc.) into uncompressed DICOMs using Explicit VR Little Endian, so that they can be ingested by a third-party system, similar to what pydicom.Dataset.decompress() does in Python (https://pydicom.github.io/pydicom/stable/reference/generated/pydicom.pixels.decompress.html).

What I need to know is whether there is a simple way in dicom-rs to:

1. Read a compressed DICOM (from a file or in-memory buffer),
2. Decode the pixel data to raw/uncompressed form,
3. Replace the pixel data in the DICOM object (and update the Transfer Syntax to Explicit VR Little Endian),
4. Write the modified DICOM object back to disk (or to a buffer), so that the resulting DICOM is fully uncompressed and accepted by my PACS/viewer.

As I’m still learning Rust, any guidance or example (even minimal) would be greatly appreciated.

Thank you very much for any guidance!
Best regards.

[Enet4]

Hello! That would be exactly what dicom-transcode does. The file in reference is a CLI, but underneath it uses the Transcode API, so you can take the relevant parts to build something like this:

use dicom_pixeldata::Transcode;

let mut obj = dicom_object::open_file(file)?;

// lookup target transfer syntax
let ts = dicom_transfer_syntax_registry::TransferSyntaxRegistry
    .get(dicom_dictionary_std::uids::EXPLICIT_VR_LITTLE_ENDIAN)
    .expect("Explicit VR Little Endian always exists");

obj.transcode(ts)?;

// write to file
obj.write_to_file(output)?;