Create filters.py (#1)

- Create filters.py (3ddca5e33d0204a6b0d670aa7fbbddba0932f9eb)

filters.py

@@ -0,0 +1,41 @@
+import cv2
+import numpy as np
+from registry import registry
+
+@registry.register("Original")
+def original(image):
+    return image
+
+@registry.register("Grayscale")
+def grayscale(image):
+    return cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
+
+@registry.register("Gaussian Blur", kernel_size=15)
+def gaussian_blur(image, kernel_size: int = 15):
+    return cv2.GaussianBlur(image, (kernel_size, kernel_size), 0)
+
+@registry.register("Pencil Sketch")
+def pencil_sketch(image):
+    gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
+    inverted = cv2.bitwise_not(gray)
+    blurred = cv2.GaussianBlur(inverted, (21, 21), 0)
+    inverted_blurred = cv2.bitwise_not(blurred)
+    return cv2.divide(gray, inverted_blurred, scale=256.0)
+
+@registry.register("Sepia")
+def sepia(image):
+    kernel = np.array([
+        [0.393, 0.769, 0.189],
+        [0.349, 0.686, 0.168],
+        [0.272, 0.534, 0.131]
+    ])
+    return cv2.transform(image, kernel)
+
+@registry.register("Edge Enhance", intensity=1.5)
+def edge_enhance(image, intensity: float = 1.5):
+    kernel = np.array([
+        [-1 * intensity, -1 * intensity, -1 * intensity],
+        [-1 * intensity,  9 * intensity, -1 * intensity],
+        [-1 * intensity, -1 * intensity, -1 * intensity]
+    ])
+    return cv2.filter2D(image, -1, kernel)