add letterbox-like resize function in the python api (#151)

* add letterbox like resize function for exceeds aspect ratio in the python api

* add cli letterbox-like control for python api

* fix det result

python/rapidocr_onnxruntime/config.yaml

@@ -6,7 +6,8 @@ Global:
     print_verbose: false
     min_height: 30
     width_height_ratio: 8
-
+    use_letterbox_like: true
+
 Det:
     use_cuda: false
 

python/rapidocr_onnxruntime/main.py

@@ -44,6 +44,7 @@ def __init__(self, config_path: Optional[str] = None, **kwargs):
         self.text_score = global_config["text_score"]
         self.min_height = global_config["min_height"]
         self.width_height_ratio = global_config["width_height_ratio"]
+        self.use_letterbox_like = global_config["use_letterbox_like"]
 
         self.use_det = global_config["use_det"]
         self.text_det = TextDetector(config["Det"])
@@ -62,11 +63,13 @@ def __call__(
         use_det: Optional[bool] = None,
         use_cls: Optional[bool] = None,
         use_rec: Optional[bool] = None,
+        use_letterbox_like: Optional[bool] = None,
         **kwargs,
     ):
         use_det = self.use_det if use_det is None else use_det
         use_cls = self.use_cls if use_cls is None else use_cls
         use_rec = self.use_rec if use_rec is None else use_rec
+        self.use_letterbox_like = self.use_letterbox_like if use_letterbox_like is None else use_letterbox_like
 
         if kwargs:
             box_thresh = kwargs.get("box_thresh", 0.5)
@@ -83,10 +86,14 @@ def __call__(
         det_elapse, cls_elapse, rec_elapse = 0.0, 0.0, 0.0
 
         if use_det:
+            zero_h = 0
+            if self.use_letterbox_like:
+                img, zero_h = self.letterbox_like(img)
+
             dt_boxes, det_elapse = self.auto_text_det(img)
             if dt_boxes is None:
                 return None, None
-
+            
             img = self.get_crop_img_list(img, dt_boxes)
 
         if use_cls:
@@ -95,27 +102,50 @@ def __call__(
         if use_rec:
             rec_res, rec_elapse = self.text_rec(img)
 
+        if zero_h > 0 and dt_boxes is not None:
+            for box in dt_boxes:
+                box[:, 1] -= zero_h
+
         ocr_res = self.get_final_res(
             dt_boxes, cls_res, rec_res, det_elapse, cls_elapse, rec_elapse
         )
         return ocr_res
 
+    def letterbox_like(self, img) :
+        img_w, img_h= img.shape[1], img.shape[0]
+
+        if self.width_height_ratio == -1:
+            use_limit_ratio = False
+        else:
+            use_limit_ratio = img_w / img_h > self.width_height_ratio
+
+        if img_h <= self.min_height or use_limit_ratio:
+            # 居中放置
+            new_h = max(int(img_w / self.width_height_ratio), self.min_height) + 1
+            zero_h = int((new_h - img_h) / 2)
+            block_img = np.zeros((new_h, img_w, 3), dtype=np.uint8)
+            block_img[zero_h: zero_h + img_h, : , :] = img
+            return block_img, zero_h
+        return img, 0
+
     def auto_text_det(
         self,
         img: np.ndarray,
     ) -> Tuple[Optional[np.ndarray], float, Optional[List[np.ndarray]]]:
         h, w = img.shape[:2]
-        if self.width_height_ratio == -1:
-            use_limit_ratio = False
-        else:
-            use_limit_ratio = w / h > self.width_height_ratio
-
-        if h <= self.min_height or use_limit_ratio:
-            logging.warning(
-                "Because the aspect ratio of the current image exceeds the limit (min_height or width_height_ratio), the program will skip the detection step."
-            )
-            dt_boxes = self.get_boxes_img_without_det(h, w)
-            return dt_boxes, 0.0
+
+        if not self.use_letterbox_like:
+            if self.width_height_ratio == -1:
+                use_limit_ratio = False
+            else:
+                use_limit_ratio = w / h > self.width_height_ratio
+
+            if h <= self.min_height or use_limit_ratio:
+                logging.warning(
+                    "Because the aspect ratio of the current image exceeds the limit (min_height or width_height_ratio), the program will skip the detection step."
+                )
+                dt_boxes = self.get_boxes_img_without_det(h, w)
+                return dt_boxes, 0.0
 
         dt_boxes, det_elapse = self.text_det(img)
         if dt_boxes is None or len(dt_boxes) < 1:
@@ -240,8 +270,9 @@ def main():
     use_det = not args.no_det
     use_cls = not args.no_cls
     use_rec = not args.no_rec
+    use_letterbox_like = not args.no_letterbox_like
     result, elapse_list = ocr_engine(
-        args.img_path, use_det=use_det, use_cls=use_cls, use_rec=use_rec
+        args.img_path, use_det=use_det, use_cls=use_cls, use_rec=use_rec, use_letterbox_like = use_letterbox_like
     )
     print(result)
 

python/rapidocr_onnxruntime/utils.py

@@ -234,7 +234,8 @@ def init_args():
     global_group.add_argument("--print_verbose", action="store_true", default=False)
     global_group.add_argument("--min_height", type=int, default=30)
     global_group.add_argument("--width_height_ratio", type=int, default=8)
-
+    global_group.add_argument("--no_letterbox_like",  action="store_true", default=False)
+
     det_group = parser.add_argument_group(title="Det")
     det_group.add_argument("--det_use_cuda", action="store_true", default=False)
     det_group.add_argument("--det_model_path", type=str, default=None)