[Bug] Error "pixelDataChunks.subarray is not a function" when loading RLE-encoded LABELMAP DICOM SEG

[rleisti]

Describe the Bug

@cornerstonejs/adapters throws TypeError: pixelDataChunks.subarray is not a function when loading a DICOM Segmentation object with SegmentationType = LABELMAP that is in RLE Lossless transfer syntax. The crash happens in processLabelmapChunk because that function calls .subarray() on pixelDataChunks, but in the RLE code path pixelDataChunks is a JS Array wrapping a single Uint8Array, not a Uint8Array itself.

Environment

• Package: @cornerstonejs/adapters 4.15.29
• File: dist/esm/adapters/Cornerstone3D/Segmentation/labelmapImagesFromBuffer.js
• Function: insertPixelDataPlanar → processLabelmapChunk
• Line: 281

Root Cause

In createLabelmapsFromBufferInternal (lines 80–98), pixelDataChunks is populated based on the SEG's transfer syntax:

  if (TransferSyntaxUID === "1.2.840.10008.1.2.5") {                                                                                                                                                     
      // RLE branch                                                                                                                                                                                      
      pixelData = decode(rleEncodedFrames, multiframe.Rows, multiframe.Columns);
      // ...                                                                                                                                                                                             
      pixelDataChunks = [pixelData];                       // <-- always a JS Array
  } else {                                                                                                                                                                                               
      pixelDataChunks = unpackPixelData(multiframe, { maxBytesPerChunk });  // returns Uint8Array | Uint16Array
  }

So:

• RLE branch: pixelDataChunks is a JS Array containing one Uint8Array. The outer Array has no .subarray method.

• Uncompressed branch: pixelDataChunks is a typed array (Uint8Array or Uint16Array), which does have .subarray.

• insertPixelDataPlanar then routes LABELMAP-type SEGs to processLabelmapChunk, where line 281 calls pixelDataChunks.subarray(...). This works for uncompressed SEGs (typed array) but throws for RLE
  SEGs (plain Array).

  The sibling code paths in the same file already handle this correctly via the imported helper readFromUnpackedChunks, used at line 197 (the non-LABELMAP planar branch) and line 356
  (getAlignedPixelData). processLabelmapChunk was apparently added later without being wired into that helper, so it only happens to work for inputs that take the uncompressed branch.

Steps to Reproduce

Load a DICOM SEG with the following characteristics through createLabelmapsFromBuffer:

Attribute	Value
(0002,0010) TransferSyntaxUID	1.2.840.10008.1.2.5 (RLE Lossless)
(0062,0001) SegmentationType	LABELMAP
(0028,0100) BitsAllocated	8
(0028,0101) BitsStored	8 (must not be 1 — bit-packed RLE is unsupported and bails out earlier)

Frame count and dimensions are not relevant; the bug fires on the first frame.

A minimal repro is to take any uncompressed LABELMAP SEG and transcode it to RLE Lossless with dcmcrle:

dcmcrle input.dcm seg_rle.dcm

The current behavior

  TypeError: pixelDataChunks.subarray is not a function                                                                                                                                                  
      at processLabelmapChunk (labelmapImagesFromBuffer.js:281)
      at insertPixelDataPlanar (...)                                                                                                                                                                     
      at createLabelmapsFromBufferInternal (...)

Offending code:

const view = pixelDataChunks.subarray(i * sliceLength, (i + 1) * sliceLength);                                                                                                                         

The expected behavior

The DICOM SEG should load without an error.

System Information

 System:
    OS: Linux 5.15 Ubuntu 22.04.5 LTS 22.04.5 LTS (Jammy Jellyfish)
    CPU: (2) x64 Intel Core Processor (Skylake, IBRS)
    Memory: 3.23 GB / 11.68 GB
    Container: Yes
    Shell: 5.1.16 - /bin/bash
  Binaries:
    Node: 22.22.0 - ~/.nvm/versions/node/v22.22.0/bin/node
    Yarn: 1.22.22 - ~/.nvm/versions/node/v22.22.0/bin/yarn
    npm: 10.9.4 - ~/.nvm/versions/node/v22.22.0/bin/npm
  Browsers:
    Chrome: 145.0.7632.159
    Firefox: 149.0

[linear]

CS-149