Basic differencing functions

differencing.py

@@ -0,0 +1,37 @@
+from typing import List, Tuple
+from pixel_types import RGB
+from PIL import Image
+
+
+def overlay_transparent(source: Image, layer: Image, differences: bool = False) -> List[Tuple[int, int]]:
+    """
+    Given an image, it wil be modified in-place to layer a (potentially transparent) Image on top.
+
+    :param source: The source image to be modified.
+    :param layer:  The layer to implant upon it.
+    :return: If specified, a list of tuples indicating pixel locations will be returned.
+    """
+    return []
+
+
+def get_pixel_differences(source: Image, target: Image) -> List[Tuple[int, int, RGB]]:
+    """
+    Returns a list of pixels (location & color) that must be changed to match `source` to `target`.
+
+    :param source: The source image (what we currently have).
+    :param target: The target image (what we want to have).
+    :return: A list of pixels in tuples.
+    """
+    source_pixels = source.load()
+    target_pixels = target.load()
+    height, width = source.shape
+    results = []
+
+    for y in range(width):
+        for x in range(height):
+            cur_pixel = source_pixels[x, y]
+            target_pixel = target_pixels[x, y]
+            if cur_pixel != target_pixel:
+                results.append((x, y, target_pixel))
+
+    return results