Add batch prediction code

Closes #31 (closed)

dan/predict.py

@@ -66,13 +66,11 @@ class DAN:
         self.mean, self.std = parameters["mean"], parameters["std"]
         self.max_chars = parameters["max_char_prediction"]
 
-    def predict(self, input_image, confidences=False):
+    def preprocess(self, input_image):
         """
-        Run prediction on an input image.
-        :param input_image: The image to predict.
-        :param confidences: Return the characters probabilities.
+        Preprocess an input_image.
+        :param input_image: The input image to preprocess.
         """
-        # Preprocess image.
         assert isinstance(
             input_image, np.ndarray
         ), "Input image must be an np.array in RGB"
@@ -80,12 +78,17 @@ class DAN:
         if len(input_image.shape) < 3:
             input_image = cv2.cvtColor(input_image, cv2.COLOR_GRAY2RGB)
 
-        reduced_size = [input_image.shape[:2]]
-
         input_image = (input_image - self.mean) / self.std
-        input_image = np.expand_dims(input_image.transpose((2, 0, 1)), axis=0)
-        input_tensor = torch.from_numpy(input_image).to(self.device)
-        logging.debug("Image pre-processed")
+        return input_image
+
+    def predict(self, input_tensor, input_sizes, confidences=False):
+        """
+        Run prediction on an input image.
+        :param input_tensor: A batch of images to predict.
+        :param input_sizes: The original images sizes.
+        :param confidences: Return the characters probabilities.
+        """
+        input_tensor.to(self.device)
 
         start_token = len(self.charset) + 1
         end_token = len(self.charset)
@@ -125,7 +128,7 @@ class DAN:
                     features,
                     enhanced_features,
                     predicted_tokens,
-                    reduced_size,
+                    input_sizes,
                     predicted_tokens_len,
                     features_size,
                     start=0,
@@ -169,8 +172,8 @@ class DAN:
             predicted_text = [
                 LM_ind_to_str(self.charset, t, oov_symbol="") for t in predicted_tokens
             ]
-            logging.info("Image processed")
+            logging.info("Images processed")
 
         if confidences:
-            return predicted_text[0], confidence_scores[0]
-        return predicted_text[0]
+            return predicted_text, confidence_scores
+        return predicted_text