Failure to create GSPS when reference DICOM uses "MultiValue" for WindowCenter, WindowWidth

[delton137]

When I go to create a GSPS using hd.pr.GrayscaleSoftcopyPresentationState() I get an error for certain DICOM where WindowWidth and WindowCenter are not floats in the reference DICOM.

Here's the error I get:

~/anaconda3/lib/python3.8/site-packages/highdicom/pr/content.py in _get_softcopy_voi_lut_transformations(referenced_images)
   1456 
   1457             if has_width:
-> 1458                 by_window[(
   1459                     ref_im.WindowWidth,
   1460                     ref_im.WindowCenter,

TypeError: unhashable type: 'MultiValue'

I fixed it using the following code:

        if isinstance(image_dataset.WindowWidth, pydicom.multival.MultiValue):
            image_dataset.WindowWidth = image_dataset.WindowWidth[0]
        if isinstance(image_dataset.WindowCenter, pydicom.multival.MultiValue):
            image_dataset.WindowCenter = image_dataset.WindowCenter[0]

This fix worked for two offending DICOM, but there is one more where I'm still getting the error. To get rid of the error there, I created the GSPS with my own windowing settings (using the argument voi_lut_transformations=[SoftcopyVOILUTObject]).

[CPBridge]

Thanks @delton137 ! I had a quick look and I think this is a simple fix. Can you try the branch in #211 and see whether that fixes the issue?

For now, the best solution is probably to manually specify the voi_lut_transformations, as you suggest.

[hackermd]

Why would these attributes have a multiplicity greater than one?

[pieper]

Why would these attributes have a multiplicity greater than one?

It's not uncommon for an image to have multiple WW/WC values in the header. They could be soft tissue and lung windows for example.

[CPBridge]

C.11.2.1.2.2, with reference to WindowCenter and WindowWidth:

If multiple values are present, both Attributes shall have the same number of values and shall be considered as pairs. Multiple values indicate that multiple alternative views may be presented.

[delton137]

I just tested @CPBridge's fix (#211) and it works! Yes, it seems multiple window settings may be saved in the DICOM.