Add ICC profile in _AssociatedImageMap

If an associated image has a profile and it's equal to the one from the
main image, reuse the latter to avoid keeping multiple copies in RAM.

Add a synthetic DICOM fixture so we can use OpenSlide's DICOM driver to
test this.  The fixture was created by hand-hacking an ICC profile into
small.svs and then converting it to DICOM with
com.pixelmed.convert.TIFFToDicom.

For openslide/openslide#477.

Signed-off-by: Benjamin Gilbert <bgilbert@cs.cmu.edu>

Author: bgilbert

MANIFEST.in

@@ -1,4 +1,4 @@
 include *.md pytest.ini
 recursive-include doc *.py *.rst
 recursive-include examples *.html *.js *.png *.py
-recursive-include tests *.png *.py *.svs *.tiff
+recursive-include tests *.dcm *.png *.py *.svs *.tiff

openslide/__init__.py

@@ -222,7 +222,7 @@ def associated_images(self):
 
         Unlike in the C interface, the images accessible via this property
         are not premultiplied."""
-        return _AssociatedImageMap(self._osr)
+        return _AssociatedImageMap(self._osr, self._profile)
 
     def get_best_level_for_downsample(self, downsample):
         """Return the best level for displaying the given downsample."""
@@ -288,13 +288,25 @@ def __getitem__(self, key):
 
 
 class _AssociatedImageMap(_OpenSlideMap):
+    def __init__(self, osr, profile):
+        _OpenSlideMap.__init__(self, osr)
+        self._profile = profile
+
     def _keys(self):
         return lowlevel.get_associated_image_names(self._osr)
 
     def __getitem__(self, key):
         if key not in self._keys():
             raise KeyError()
-        return lowlevel.read_associated_image(self._osr, key)
+        image = lowlevel.read_associated_image(self._osr, key)
+        if lowlevel.read_associated_image_icc_profile.available:
+            profile = lowlevel.read_associated_image_icc_profile(self._osr, key)
+            if profile == self._profile:
+                # reuse profile copy from main image to save memory
+                profile = self._profile
+            if profile is not None:
+                image.info['icc_profile'] = profile
+        return image
 
 
 class OpenSlideCache:

openslide/lowlevel.py

@@ -405,6 +405,33 @@ def read_associated_image(slide, name):
     return _load_image(buf, (w, h))
 
 
+get_associated_image_icc_profile_size = _func(
+    'openslide_get_associated_image_icc_profile_size',
+    c_int64,
+    [_OpenSlide, _utf8_p],
+    minimum_version='4.0.0',
+)
+
+_read_associated_image_icc_profile = _func(
+    'openslide_read_associated_image_icc_profile',
+    None,
+    [_OpenSlide, _utf8_p, POINTER(c_char)],
+    minimum_version='4.0.0',
+)
+
+
+@_wraps_funcs(
+    [get_associated_image_icc_profile_size, _read_associated_image_icc_profile]
+)
+def read_associated_image_icc_profile(slide, name):
+    size = get_associated_image_icc_profile_size(slide, name)
+    if size == 0:
+        return None
+    buf = (size * c_char)()
+    _read_associated_image_icc_profile(slide, name, buf)
+    return buf.raw
+
+
 get_version = _func('openslide_get_version', c_char_p, [], _check_string)
 
 cache_create = _func(

tests/fixtures/boxes_0.dcm

@@ -196,6 +196,23 @@ def test_color_profile(self):
         self.assertNotIn(
             'icc_profile', self.osr.read_region((0, 0), 0, (100, 100)).info
         )
+        self.assertNotIn('icc_profile', self.osr.associated_images['thumbnail'].info)
+
+
+# Requires DICOM support in OpenSlide.  Use associated image ICC support as
+# a proxy.
+@unittest.skipUnless(
+    lowlevel.read_associated_image_icc_profile.available, "requires OpenSlide 4.0.0"
+)
+class TestDicomSlide(_SlideTest, unittest.TestCase):
+    FILENAME = 'boxes_0.dcm'
+
+    def test_color_profile(self):
+        main_profile = self.osr.read_region((0, 0), 0, (100, 100)).info['icc_profile']
+        associated_profile = self.osr.associated_images['thumbnail'].info['icc_profile']
+        self.assertEqual(len(main_profile), 456)
+        self.assertEqual(main_profile, associated_profile)
+        self.assertIs(main_profile, associated_profile)
 
 
 class TestUnreadableSlide(_SlideTest, unittest.TestCase):