add BC4 images

nb: the bc4/ati1 dds files are actually slightly wrong, seems like nvtt has a bug and endpoints are off by 1 sometimes

.gitattributes

@@ -1,2 +1,3 @@
 *.png filter=lfs diff=lfs merge=lfs -text
 *.afdesign filter=lfs diff=lfs merge=lfs -text
+*.dds filter=lfs diff=lfs merge=lfs -text

.gitignore

@@ -0,0 +1 @@
+__pycache__

__init__.py

@@ -1,17 +1,33 @@
 from PIL import Image
-import os
+from quicktex.s3tc.bc1 import BC1Block
+from quicktex.s3tc.bc4 import BC4Block
+from quicktex import RawTexture
+import os.path
 
 image_path = os.path.dirname(os.path.realpath(__file__))
 
 
-class Blocks:
-    # A block that should always encode greyscale, where every row of pixels is identical, and the left side is lighter than the right side
-    greyscale = Image.open(image_path + "/blocks/greyscale.png").tobytes("raw", "RGBX")
+class BC1Blocks:
+    class Entry:
+        def __init__(self, filename, block):
+            path = os.path.join(image_path, 'bc1', filename)
+            self.image = Image.open(path).convert('RGBA')
+            self.texture = RawTexture.frombytes(self.image.tobytes('raw', 'RGBA'), *self.image.size)
+            self.block = block
 
-    # A block that should always encode 3-color when available.
-    # from left to right: red, yellow, yellow, green
-    three_color = Image.open(image_path + "/blocks/3color.png").tobytes("raw", "RGBX")
+    greyscale = Entry('greyscale_unpacked.png', BC1Block.frombytes(b'\xFF\xFF\x49\x4A\x78\x78\x78\x78'))
+    three_color = Entry('3color_unpacked.png', BC1Block.frombytes(b'\xE0\x07\x00\xF8\x29\x29\x29\x29'))
+    three_color_black = Entry('3color_black_unpacked.png', BC1Block.frombytes(b'\xE0\x07\x00\xF8\x27\x27\x27\x27'))
+
+
+class BC4Blocks:
+    class Entry:
+        def __init__(self, filename, block):
+            path = os.path.join(image_path, 'bc4', filename)
+            self.image = Image.open(path).convert('RGBA')
+            self.texture = RawTexture.frombytes(self.image.tobytes('raw', 'RGBA'), *self.image.size)
+            self.block = block
+
+    six_value = Entry('6value.png', BC4Block(8, 248, [[0, 1, 2, 3]] * 2 + [[4, 5, 6, 7]] * 2))
+    eight_value = Entry('8value.png', BC4Block(240, 16, [[0, 1, 2, 3]] * 2 + [[4, 5, 6, 7]] * 2))
 
-    # A block that should always encode 3-color with black when available
-    # from left to right: black, red, yellow, green
-    three_color_black = Image.open(image_path + "/blocks/3color black.png").tobytes("raw", "RGBX")