Merge pull request #462 from aleju/grayscale_some_colors

Add augmenters for colorwise grayscaling

changelogs/master/added/20191019_colorwise_grayscaling.md

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+# Colorwise Grayscaling #462
+
+* Added `RemoveSaturation`, a shortcut for `MultiplySaturation((0.0, 1.0))`
+  with outputs similar to `Grayscale((0.0, 1.0))`.
+* Added `GrayscaleColorwise`, which applies grayscaling to randomly
+  picked colors in the image.
+* Added `RemoveSaturationColorwise`, which applies color saturation removal
+  to randomy picked colors in the image.

checks/check_grayscale_colorwise.py

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+import imgaug as ia
+import imgaug.augmenters as iaa
+import imageio
+
+
+def main():
+    urls = [
+        ("https://upload.wikimedia.org/wikipedia/commons/thumb/4/43/"
+         "Sarcophilus_harrisii_taranna.jpg/"
+         "320px-Sarcophilus_harrisii_taranna.jpg"),
+        ("https://upload.wikimedia.org/wikipedia/commons/thumb/b/ba/"
+         "Vincent_van_Gogh_-_Wheatfield_with_crows_-_Google_Art_Project.jpg/"
+         "320px-Vincent_van_Gogh_-_Wheatfield_with_crows_-_Google_Art_Project"
+         ".jpg"),
+        ("https://upload.wikimedia.org/wikipedia/commons/thumb/0/0c/"
+         "Galerella_sanguinea_Zoo_Praha_2011-2.jpg/207px-Galerella_sanguinea_"
+         "Zoo_Praha_2011-2.jpg"),
+        ("https://upload.wikimedia.org/wikipedia/commons/thumb/9/96/"
+         "Ambrosius_Bosschaert_the_Elder_%28Dutch_-_Flower_Still_Life_-_"
+         "Google_Art_Project.jpg/307px-Ambrosius_Bosschaert_the_Elder_%28"
+         "Dutch_-_Flower_Still_Life_-_Google_Art_Project.jpg")
+    ]
+
+    image = imageio.imread(urls[1])
+
+    aug = iaa.GrayscaleColorwise(10, 0.1, alpha=[0.0, 1.0])
+    images_aug = aug(images=[image] * (5*5))
+
+    ia.imshow(ia.draw_grid(images_aug))
+
+
+if __name__ == "__main__":
+    main()

checks/check_remove_saturation.py

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+import imgaug as ia
+import imgaug.augmenters as iaa
+import imageio
+
+
+def main():
+    urls = [
+        ("https://upload.wikimedia.org/wikipedia/commons/thumb/4/43/"
+         "Sarcophilus_harrisii_taranna.jpg/"
+         "320px-Sarcophilus_harrisii_taranna.jpg"),
+        ("https://upload.wikimedia.org/wikipedia/commons/thumb/b/ba/"
+         "Vincent_van_Gogh_-_Wheatfield_with_crows_-_Google_Art_Project.jpg/"
+         "320px-Vincent_van_Gogh_-_Wheatfield_with_crows_-_Google_Art_Project"
+         ".jpg"),
+        ("https://upload.wikimedia.org/wikipedia/commons/thumb/0/0c/"
+         "Galerella_sanguinea_Zoo_Praha_2011-2.jpg/207px-Galerella_sanguinea_"
+         "Zoo_Praha_2011-2.jpg"),
+        ("https://upload.wikimedia.org/wikipedia/commons/thumb/9/96/"
+         "Ambrosius_Bosschaert_the_Elder_%28Dutch_-_Flower_Still_Life_-_"
+         "Google_Art_Project.jpg/307px-Ambrosius_Bosschaert_the_Elder_%28"
+         "Dutch_-_Flower_Still_Life_-_Google_Art_Project.jpg")
+    ]
+
+    image = imageio.imread(urls[3])
+
+    aug = iaa.RemoveSaturation()
+    images_aug = aug(images=[image] * (5*5))
+
+    ia.imshow(ia.draw_grid(images_aug))
+
+
+if __name__ == "__main__":
+    main()

checks/check_remove_saturation_colorwise.py

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+import imgaug as ia
+import imgaug.augmenters as iaa
+import imageio
+
+
+def main():
+    urls = [
+        ("https://upload.wikimedia.org/wikipedia/commons/thumb/4/43/"
+         "Sarcophilus_harrisii_taranna.jpg/"
+         "320px-Sarcophilus_harrisii_taranna.jpg"),
+        ("https://upload.wikimedia.org/wikipedia/commons/thumb/b/ba/"
+         "Vincent_van_Gogh_-_Wheatfield_with_crows_-_Google_Art_Project.jpg/"
+         "320px-Vincent_van_Gogh_-_Wheatfield_with_crows_-_Google_Art_Project"
+         ".jpg"),
+        ("https://upload.wikimedia.org/wikipedia/commons/thumb/0/0c/"
+         "Galerella_sanguinea_Zoo_Praha_2011-2.jpg/207px-Galerella_sanguinea_"
+         "Zoo_Praha_2011-2.jpg"),
+        ("https://upload.wikimedia.org/wikipedia/commons/thumb/9/96/"
+         "Ambrosius_Bosschaert_the_Elder_%28Dutch_-_Flower_Still_Life_-_"
+         "Google_Art_Project.jpg/307px-Ambrosius_Bosschaert_the_Elder_%28"
+         "Dutch_-_Flower_Still_Life_-_Google_Art_Project.jpg")
+    ]
+
+    image = imageio.imread(urls[1])
+
+    aug = iaa.RemoveSaturationColorwise(10, 0.1, alpha=[0.0, 1.0])
+    images_aug = aug(images=[image] * (5*5))
+
+    ia.imshow(ia.draw_grid(images_aug))
+
+
+if __name__ == "__main__":
+    main()