Merge pull request #2957 from mchapman87501/preserve-icc-profiles

Preserve image ICC profiles

AUTHORS.txt

@@ -75,6 +75,7 @@
 * `Michael McNeil Forbes <https://github.com/mforbes>`_
 * `Michal Petrucha <https://github.com/koniiiik>`_
 * `Miguel Ángel García <https://github.com/magmax>`_
+* `Mitch Chapman <https://github.com/mchapman87501>`_
 * `mrabbitt <https://github.com/mrabbitt>`_
 * `Neil MartinsenBurrell <https://github.com/neilmb>`_
 * `Niels Böhm <https://github.com/blubberdiblub>`_

CHANGES.txt

@@ -3,7 +3,7 @@ New in master
 
 Features
 --------
-
+* New PRESERVE_ICC_PROFILES option to control whether ICC profiles are preserved when copying images.
 * Use baguetteJS in bootstrap theme (part of Issue #2777)
 * New default-config command to generate a clean configuration.
 * New ``thumbnail`` shortcode similar to the reStructuredText

docs/manual.txt

@@ -1995,6 +1995,22 @@ listed there.
 There is a huge number of EXIF tags, described in `the standard <http://www.cipa.jp/std/documents/e/DC-008-2012_E.pdf>`__
 
 
+Handling ICC Profiles
+---------------------
+
+Your images may contain `ICC profiles. <https://en.wikipedia.org/wiki/ICC_profile>`__  These describe the color space in which the images were created or captured.
+
+Most desktop web browsers can use embedded ICC profiles to display images accurately.  As of early 2018 few mobile browsers consider ICC profiles when displaying images.  A notable exception is Safari on iOS.
+
+By default Nikola strips out ICC profiles when preparing images for your posts and galleries.  If you want Nikola to preserve ICC profiles, add this in your ``conf.py``:
+
+.. code:: python
+
+  PRESERVE_ICC_PROFILES = True
+
+You may wish to do this if, for example, your site contains JPEG images that use a wide-gamut profile such as "Display P3".
+
+
 Post Processing Filters
 -----------------------
 

nikola/conf.py.in

@@ -703,6 +703,10 @@ GITHUB_COMMIT_SOURCE = True
 # Embedded thumbnail information:
 # EXIF_WHITELIST['1st'] = ["*"]
 
+# If set to True, any ICC profile will be copied when an image is thumbnailed or
+# resized.
+# PRESERVE_ICC_PROFILES = False
+
 # Folders containing images to be used in normal posts or pages.
 # IMAGE_FOLDERS is a dictionary of the form {"source": "destination"},
 # where "source" is the folder containing the images to be published, and

nikola/image_processing.py

@@ -91,7 +91,7 @@ def filter_exif(self, exif, whitelist):
 
         return exif or None
 
-    def resize_image(self, src, dst, max_size, bigger_panoramas=True, preserve_exif_data=False, exif_whitelist={}):
+    def resize_image(self, src, dst, max_size, bigger_panoramas=True, preserve_exif_data=False, exif_whitelist={}, preserve_icc_profiles=False):
         """Make a copy of the image in the requested size."""
         if not Image or os.path.splitext(src)[1] in ['.svg', '.svgz']:
             self.resize_svg(src, dst, max_size, bigger_panoramas)
@@ -131,6 +131,7 @@ def resize_image(self, src, dst, max_size, bigger_panoramas=True, preserve_exif_
             exif['0th'][piexif.ImageIFD.Orientation] = 1
 
         try:
+            icc_profile = im.info.get('icc_profile') if preserve_icc_profiles else None
             im.thumbnail(size, Image.ANTIALIAS)
             if exif is not None and preserve_exif_data:
                 # Put right size in EXIF data
@@ -143,9 +144,9 @@ def resize_image(self, src, dst, max_size, bigger_panoramas=True, preserve_exif_
                     exif["Exif"][piexif.ExifIFD.PixelYDimension] = h
                 # Filter EXIF data as required
                 exif = self.filter_exif(exif, exif_whitelist)
-                im.save(dst, exif=piexif.dump(exif))
+                im.save(dst, exif=piexif.dump(exif), icc_profile=icc_profile)
             else:
-                im.save(dst)
+                im.save(dst, icc_profile=icc_profile)
         except Exception as e:
             self.logger.warn("Can't process {0}, using original "
                              "image! ({1})".format(src, e))

nikola/nikola.py

@@ -563,6 +563,7 @@ def __init__(self, **config):
             'POSTS_SECTION_TRANSLATIONS': [],
             'POSTS_SECTION_TRANSLATIONS_ADD_DEFAULTS': False,
             'PRESERVE_EXIF_DATA': False,
+            'PRESERVE_ICC_PROFILES': False,
             'PAGES': (("pages/*.txt", "pages", "page.tmpl"),),
             'PANDOC_OPTIONS': [],
             'PRETTY_URLS': True,

nikola/plugins/task/galleries.py

@@ -86,6 +86,7 @@ def set_site(self, site):
             'generate_rss': site.config['GENERATE_RSS'],
             'preserve_exif_data': site.config['PRESERVE_EXIF_DATA'],
             'exif_whitelist': site.config['EXIF_WHITELIST'],
+            'preserve_icc_profiles': site.config['PRESERVE_ICC_PROFILES'],
         }
 
         # Verify that no folder in GALLERY_FOLDERS appears twice
@@ -481,7 +482,7 @@ def create_target_images(self, img, input_path):
             'actions': [
                 (self.resize_image,
                     (img, thumb_path, self.kw['thumbnail_size'], True, self.kw['preserve_exif_data'],
-                     self.kw['exif_whitelist']))
+                     self.kw['exif_whitelist'], self.kw['preserve_icc_profiles']))
             ],
             'clean': True,
             'uptodate': [utils.config_changed({
@@ -497,7 +498,7 @@ def create_target_images(self, img, input_path):
             'actions': [
                 (self.resize_image,
                     (img, orig_dest_path, self.kw['max_image_size'], True, self.kw['preserve_exif_data'],
-                     self.kw['exif_whitelist']))
+                     self.kw['exif_whitelist'], self.kw['preserve_icc_profiles']))
             ],
             'clean': True,
             'uptodate': [utils.config_changed({

nikola/plugins/task/scale_images.py

@@ -71,8 +71,8 @@ def process_tree(self, src, dst):
 
     def process_image(self, src, dst, thumb):
         """Resize an image."""
-        self.resize_image(src, dst, self.kw['max_image_size'], True, preserve_exif_data=self.kw['preserve_exif_data'], exif_whitelist=self.kw['exif_whitelist'])
-        self.resize_image(src, thumb, self.kw['image_thumbnail_size'], True, preserve_exif_data=self.kw['preserve_exif_data'], exif_whitelist=self.kw['exif_whitelist'])
+        self.resize_image(src, dst, self.kw['max_image_size'], True, preserve_exif_data=self.kw['preserve_exif_data'], exif_whitelist=self.kw['exif_whitelist'], preserve_icc_profiles=self.kw['preserve_icc_profiles'])
+        self.resize_image(src, thumb, self.kw['image_thumbnail_size'], True, preserve_exif_data=self.kw['preserve_exif_data'], exif_whitelist=self.kw['exif_whitelist'], preserve_icc_profiles=self.kw['preserve_icc_profiles'])
 
     def gen_tasks(self):
         """Copy static files into the output folder."""
@@ -85,6 +85,7 @@ def gen_tasks(self):
             'filters': self.site.config['FILTERS'],
             'preserve_exif_data': self.site.config['PRESERVE_EXIF_DATA'],
             'exif_whitelist': self.site.config['EXIF_WHITELIST'],
+            'preserve_icc_profiles': self.site.config['PRESERVE_ICC_PROFILES'],
         }
 
         self.image_ext_list = self.image_ext_list_builtin

tests/README.rst

@@ -24,6 +24,7 @@ Tests (in alphabetical order)
 * ``test_rst_compiler`` exercises the reStructuredText compiler plugin of
   Nikola.
 * ``test_scheduling`` performs tests on post scheduling rules.
+* ``test_task_scale_images`` performs basic tests on the scale_images task plugin.
 * ``test_utils`` test various Nikola utilities.
 
 Requirements to run the tests

tests/test_task_scale_images.py

@@ -0,0 +1,113 @@
+# -*- coding: utf-8 -*-
+# As prescribed in README.rst:
+import os
+import unittest
+import tempfile
+from PIL import Image, ImageDraw
+
+from nikola.plugins.task import scale_images
+# Import test - should perhaps be moved to a separate module
+import nikola.plugins.task.galleries  # NOQA
+from .base import FakeSite
+
+
+class TestCase(unittest.TestCase):
+    def setUp(self):
+        # These tests don't require valid profiles.  They need only to verify
+        # that profile data is/isn't saved with images.
+        # It would be nice to use PIL.ImageCms to create valid profiles, but
+        # in many Pillow distributions ImageCms is a stub.
+        # ICC file data format specification:
+        # http://www.color.org/icc32.pdf
+
+        self._profile = b'invalid profile data'
+
+        # Make a white image with a red stripe on the diagonal.
+        w = 64
+        h = 64
+        img = Image.new("RGB", (w, h), (255, 255, 255))
+        draw = ImageDraw.Draw(img)
+        draw.line((0, 0, w, h), fill=(255, 128, 128))
+        draw.line((w, 0, 0, h), fill=(128, 128, 255))
+        self._img = img
+
+        self._src_dir = tempfile.TemporaryDirectory()
+        self._dest_dir = tempfile.TemporaryDirectory()
+
+    def tearDown(self):
+        pass
+
+    def _tmp_img_name(self, dirname):
+        pathname = tempfile.NamedTemporaryFile(
+            suffix=".jpg", dir=dirname, delete=False)
+        return pathname.name
+
+    def _get_site(self, preserve_icc_profiles):
+        site = FakeSite()
+        site.config['IMAGE_FOLDERS'] = {self._src_dir.name: ''}
+        site.config['OUTPUT_FOLDER'] = self._dest_dir.name
+        site.config['IMAGE_THUMBNAIL_SIZE'] = 128
+        site.config['IMAGE_THUMBNAIL_FORMAT'] = '{name}.thumbnail{ext}'
+        site.config['MAX_IMAGE_SIZE'] = 512
+        site.config['FILTERS'] = {}
+        site.config['PRESERVE_EXIF_DATA'] = False
+        site.config['EXIF_WHITELIST'] = {}
+        site.config['PRESERVE_ICC_PROFILES'] = preserve_icc_profiles
+        return site
+
+    def _get_task_instance(self, preserve_icc_profiles):
+        result = scale_images.ScaleImage()
+        result.set_site(self._get_site(preserve_icc_profiles))
+        return result
+
+    def _create_src_images(self):
+        img = self._img
+        # Test two variants: with and without an associated icc_profile
+        pathname = self._tmp_img_name(self._src_dir.name)
+        img.save(pathname)
+        sans_icc_filename = os.path.basename(pathname)
+
+        pathname = self._tmp_img_name(self._src_dir.name)
+        img.save(pathname, icc_profile=self._profile)
+        with_icc_filename = os.path.basename(pathname)
+        return [sans_icc_filename, with_icc_filename]
+
+    def _run_task(self, preserve_icc_profiles):
+        task_instance = self._get_task_instance(preserve_icc_profiles)
+        for task in task_instance.gen_tasks():
+            for action, args in task.get('actions', []):
+                action(*args)
+
+    def test_scale_preserving_icc_profile(self):
+        sans_icc_filename, with_icc_filename = self._create_src_images()
+        self._run_task(True)
+        cases = [
+            (sans_icc_filename, None),
+            (with_icc_filename, self._profile),
+        ]
+        for (filename, expected_profile) in cases:
+            pathname = os.path.join(self._dest_dir.name, filename)
+            self.assertTrue(os.path.exists(pathname), pathname)
+            img = Image.open(pathname)
+            actual_profile = img.info.get('icc_profile')
+            self.assertEqual(actual_profile, expected_profile)
+
+    def test_scale_discarding_icc_profile(self):
+        sans_icc_filename, with_icc_filename = self._create_src_images()
+        self._run_task(False)
+        cases = [
+            (sans_icc_filename, None),
+            (with_icc_filename, None),
+        ]
+        for (filename, expected_profile) in cases:
+            pathname = os.path.join(self._dest_dir.name, filename)
+            self.assertTrue(os.path.exists(pathname), pathname)
+            img = Image.open(pathname)
+            actual_profile = img.info.get('icc_profile')
+            self.assertEqual(actual_profile, expected_profile)
+
+
+main = unittest.main
+
+if __name__ == '__main__':
+    main()