Add ICC profile in OpenSlide.read_region()

Take care to reuse the same profile so we're not keeping multiple copies
in RAM.

Add sRGB profile to boxes.tiff fixture.

For openslide/openslide#469.

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

Author: bgilbert

openslide/__init__.py

@@ -2,7 +2,7 @@
 # openslide-python - Python bindings for the OpenSlide library
 #
 # Copyright (c) 2010-2014 Carnegie Mellon University
-# Copyright (c) 2021      Benjamin Gilbert
+# Copyright (c) 2021-2023 Benjamin Gilbert
 #
 # This library is free software; you can redistribute it and/or modify it
 # under the terms of version 2.1 of the GNU Lesser General Public License
@@ -55,6 +55,9 @@
 class AbstractSlide:
     """The base class of a slide object."""
 
+    def __init__(self):
+        self._profile = None
+
     def __enter__(self):
         return self
 
@@ -164,6 +167,8 @@ def __init__(self, filename):
         AbstractSlide.__init__(self)
         self._filename = filename
         self._osr = lowlevel.open(str(filename))
+        if lowlevel.read_icc_profile.available:
+            self._profile = lowlevel.read_icc_profile(self._osr)
 
     def __repr__(self):
         return f'{self.__class__.__name__}({self._filename!r})'
@@ -233,9 +238,12 @@ def read_region(self, location, level, size):
 
         Unlike in the C interface, the image data returned by this
         function is not premultiplied."""
-        return lowlevel.read_region(
+        region = lowlevel.read_region(
             self._osr, location[0], location[1], level, size[0], size[1]
         )
+        if self._profile is not None:
+            region.info['icc_profile'] = self._profile
+        return region
 
     def set_cache(self, cache):
         """Use the specified cache to store recently decoded slide tiles.

openslide/lowlevel.py

@@ -33,6 +33,7 @@
 from ctypes import (
     POINTER,
     byref,
+    c_char,
     c_char_p,
     c_double,
     c_int32,
@@ -335,6 +336,31 @@ def read_region(slide, x, y, level, w, h):
     return _load_image(buf, (w, h))
 
 
+get_icc_profile_size = _func(
+    'openslide_get_icc_profile_size',
+    c_int64,
+    [_OpenSlide],
+    minimum_version='4.0.0',
+)
+
+_read_icc_profile = _func(
+    'openslide_read_icc_profile',
+    None,
+    [_OpenSlide, POINTER(c_char)],
+    minimum_version='4.0.0',
+)
+
+
+@_wraps_funcs([get_icc_profile_size, _read_icc_profile])
+def read_icc_profile(slide):
+    size = get_icc_profile_size(slide)
+    if size == 0:
+        return None
+    buf = (size * c_char)()
+    _read_icc_profile(slide, buf)
+    return buf.raw
+
+
 get_error = _func('openslide_get_error', c_char_p, [_OpenSlide], _check_string)
 
 get_property_names = _func(

tests/fixtures/boxes.tiff

@@ -123,6 +123,14 @@ def test_properties(self):
             repr(self.osr.properties), '<_PropertyMap %r>' % dict(self.osr.properties)
         )
 
+    @unittest.skipUnless(
+        lowlevel.read_icc_profile.available, "requires OpenSlide 4.0.0"
+    )
+    def test_color_profile(self):
+        self.assertEqual(
+            len(self.osr.read_region((0, 0), 0, (100, 100)).info['icc_profile']), 588
+        )
+
     def test_read_region(self):
         self.assertEqual(
             self.osr.read_region((-10, -10), 1, (400, 400)).size, (400, 400)
@@ -184,6 +192,11 @@ def mangle_repr(o):
             '<_AssociatedImageMap %s>' % mangle_repr(dict(self.osr.associated_images)),
         )
 
+    def test_color_profile(self):
+        self.assertNotIn(
+            'icc_profile', self.osr.read_region((0, 0), 0, (100, 100)).info
+        )
+
 
 class TestUnreadableSlide(_SlideTest, unittest.TestCase):
     FILENAME = 'unreadable.svs'