feat: adaptation of Canny processor

Adapted from controlnet processors package

fix: do final resize in canny processor

canny

invokeai/backend/image_util/canny.py

@@ -0,0 +1,41 @@
+import cv2
+from PIL import Image
+
+from invokeai.backend.image_util.util import (
+    cv2_to_pil,
+    fit_image_to_resolution,
+    normalize_image_channel_count,
+    pil_to_cv2,
+)
+
+
+def get_canny_edges(
+    image: Image.Image, low_threshold: int, high_threshold: int, detect_resolution: int, image_resolution: int
+) -> Image.Image:
+    """Returns the edges of an image using the Canny edge detection algorithm.
+
+    This function is adapted from https://github.com/lllyasviel/ControlNet.
+
+    Args:
+        image: The input image.
+        low_threshold: The lower threshold for the hysteresis procedure.
+        high_threshold: The upper threshold for the hysteresis procedure.
+        input_resolution: The resolution of the input image. The image will be resized to this resolution before edge detection.
+        output_resolution: The resolution of the output image. The edges will be resized to this resolution before returning.
+
+    Returns:
+        The Canny edges of the input image.
+    """
+
+    if image.mode != "RGB":
+        image = image.convert("RGB")
+
+    np_image = pil_to_cv2(image)
+    np_image = normalize_image_channel_count(np_image)
+    np_image = fit_image_to_resolution(np_image, detect_resolution)
+
+    edge_map = cv2.Canny(np_image, low_threshold, high_threshold)
+    edge_map = normalize_image_channel_count(edge_map)
+    edge_map = fit_image_to_resolution(edge_map, image_resolution)
+
+    return cv2_to_pil(edge_map)