Merge pull request #1376 from girder/tifffile-mag-values

Guard against bad tifffile magnification values
girder · Nov 16, 2023 · a95f81e · a95f81e
2 parents 329226e + 6ac14e2
commit a95f81e
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -21,6 +21,7 @@
 - Fix series detection for some bioformats files ([#1365](../../pull/1365), [#1367](../../pull/1367))
 - Fix time comparison in annotation history check ([#1369](../../pull/1369))
 - Fix an issue with apply a frame style to ome tiffs ([#1374](../../pull/1374))
+- Guard against bad tifffile magnification values ([#1376](../../pull/1376))
 
 ## 1.26.0
 

diff --git a/sources/tifffile/large_image_source_tifffile/__init__.py b/sources/tifffile/large_image_source_tifffile/__init__.py
@@ -125,10 +125,12 @@ def __init__(self, path, **kwargs):  # noqa
         try:
             unit = {2: 25.4, 3: 10}[page.tags['ResolutionUnit'].value.real]
 
-            if page.tags['XResolution'].value[1] >= 100:
+            if (page.tags['XResolution'].value[0] and (
+                    page.tags['XResolution'].value[1] / page.tags['XResolution'].value[0]) >= 100):
                 self._mm_x = (unit * page.tags['XResolution'].value[1] /
                               page.tags['XResolution'].value[0])
-            if page.tags['YResolution'].value[1] >= 100:
+            if (page.tags['YResolution'].value[0] and (
+                    page.tags['YResolution'].value[1] / page.tags['YResolution'].value[0]) >= 100):
                 self._mm_y = (unit * page.tags['YResolution'].value[1] /
                               page.tags['YResolution'].value[0])
         except Exception: