Opt: Delete low confidence result in OCR

module/base/utils.py

@@ -330,6 +330,24 @@ def extract_letters(image, letter=(255, 255, 255), threshold=128):
     return cv2.multiply(cv2.add(positive, negative), 255.0 / threshold)
 
 
+def extract_white_letters(image, threshold=128):
+    """Set letter color to black, set background color to white.
+    This function will discourage color pixels (Non-gray pixels)
+
+    Args:
+        image: Shape (height, width, channel)
+        threshold (int):
+
+    Returns:
+        np.ndarray: Shape (height, width)
+    """
+    image = np.array(image)
+    r, g, b = cv2.split(cv2.subtract((255, 255, 255, 0), image))
+    minimum = cv2.min(cv2.min(r, g), b)
+    maximum = cv2.max(cv2.max(r, g), b)
+    return cv2.multiply(cv2.add(maximum, cv2.subtract(maximum, minimum)), 255.0 / threshold)
+
+
 def red_overlay_transparency(color1, color2, red=247):
     """Calculate the transparency of red overlay.