Failing with 19 channels

[FaehlingT]

Hi and thanks for the great tool :)

When using the fileseries command on a fileseries with 19 channels, ashlar fails at the process of saving the pyramid when I have it save all channels. When I limit it to ≤18 channels, it works (regardless of the channel I omit). Now, I also had the same problem when running 18 channels, which usually worked.
Command that works mostly:

ashlar 'fileseries|/path/to/raw|pattern=tile{series:2}.ome.tiff|width=5|height=6|pixel_size=0.182|overlap=0.05' \
            -o /path/to/output.ome.tif \
            -c 17 \
            --flip-x \
            --output-channels 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 16 17 18 \ # it does not matter which channel I omit here
            --maximum-shift 2 \
            --ffp '/path/to/ffp.tif' \
            --dfp '/path/to/dfp.tif';

Command that never worked:

ashlar 'fileseries|/path/to/raw|pattern=tile{series:2}.ome.tiff|width=5|height=6|pixel_size=0.182|overlap=0.05' \
            -o /path/to/output.ome.tif \
            -c 17 \
            --flip-x \
            --maximum-shift 2 \
            --ffp '/path/to/ffp.tif' \
            --dfp '/path/to/dfp.tif';

It shows the following error message:

...
Channel 18:
    merging tile 35/35
Generating pyramid
  Level 1 (12788 x 15437)
<tifffile.TiffPages @16> invalid page offset 3250604960 # the page offset varies when I repeat the process
    processing channel 3/19Traceback (most recent call last): # It happens in different channels.
 File “/home/xx/.local/bin/ashlar”, line 8, in <module>
  sys.exit(main())
 File “/home/xx/.local/lib/python3.9/site-packages/ashlar/scripts/ashlar.py”, line 212, in main
  return process_single(
 File “/home/xx/.local/lib/python3.9/site-packages/ashlar/scripts/ashlar.py”, line 277, in process_single
  writer.run()
 File “/home/xx/.local/lib/python3.9/site-packages/ashlar/reg.py”, line 1247, in run
  tiff.write(
 File “/home/xx/.local/lib/python3.9/site-packages/tifffile/tifffile.py”, line 3337, in write
  iteritem = next(dataiter)
 File “/home/xx/.local/lib/python3.9/site-packages/tifffile/tifffile.py”, line 22910, in newiter
  yield from iterator
 File “/home/xx/.local/lib/python3.9/site-packages/ashlar/reg.py”, line 1206, in subres_tiles
  a = zimg[c, y:y+th, x:x+tw, 0]
 File “/home/xx/.local/lib/python3.9/site-packages/zarr/core.py”, line 842, in __getitem__
  result = self.get_orthogonal_selection(pure_selection, fields=fields)
 File “/home/xx/.local/lib/python3.9/site-packages/zarr/core.py”, line 1122, in get_orthogonal_selection
  indexer = OrthogonalIndexer(selection, self)
 File “/home/xx/.local/lib/python3.9/site-packages/zarr/indexing.py”, line 617, in __init__
  dim_indexer = IntDimIndexer(dim_sel, dim_len, dim_chunk_len)
 File “/home/xx/.local/lib/python3.9/site-packages/zarr/indexing.py”, line 150, in __init__
  dim_sel = normalize_integer_selection(dim_sel, dim_len)
 File “/home/xx/.local/lib/python3.9/site-packages/zarr/indexing.py”, line 124, in normalize_integer_selection
  raise BoundsCheckError(dim_len)
zarr.errors.BoundsCheckError: index out of bounds for dimension with length 2

[jmuhlich]

What version of ashlar, tifffile, and zarr do you have installed?