diff --git a/PPOCRLabel/PPOCRLabel.py b/PPOCRLabel/PPOCRLabel.py
index 34c045e96aa10ba678447eefc1d007f9042804b8..7d1df9d2034b4ec927a2ac3a879861df62f78a28 100644
--- a/PPOCRLabel/PPOCRLabel.py
+++ b/PPOCRLabel/PPOCRLabel.py
@@ -379,7 +379,7 @@ class MainWindow(QMainWindow):
                         'w', 'objects', getStr('crtBoxDetail'), enabled=False)
 
         delete = action(getStr('delBox'), self.deleteSelectedShape,
-                        'Alt+X', 'delete', getStr('delBoxDetail'), enabled=False)
+                        'backspace', 'delete', getStr('delBoxDetail'), enabled=False)
 
         copy = action(getStr('dupBox'), self.copySelectedShape,
                       'Ctrl+C', 'copy', getStr('dupBoxDetail'),
@@ -1931,6 +1931,38 @@ class MainWindow(QMainWindow):
             owidth += itemwidget.width()
         self.iconlist.setMinimumWidth(owidth + 50)
 
+    def gen_quad_from_poly(self, poly):
+        """
+        Generate min area quad from poly.
+        """
+        point_num = poly.shape[0]
+        min_area_quad = np.zeros((4, 2), dtype=np.float32)
+        rect = cv2.minAreaRect(poly.astype(
+            np.int32))  # (center (x,y), (width, height), angle of rotation)
+        box = np.array(cv2.boxPoints(rect))
+
+        first_point_idx = 0
+        min_dist = 1e4
+        for i in range(4):
+            dist = np.linalg.norm(box[(i + 0) % 4] - poly[0]) + \
+                   np.linalg.norm(box[(i + 1) % 4] - poly[point_num // 2 - 1]) + \
+                   np.linalg.norm(box[(i + 2) % 4] - poly[point_num // 2]) + \
+                   np.linalg.norm(box[(i + 3) % 4] - poly[-1])
+            if dist < min_dist:
+                min_dist = dist
+                first_point_idx = i
+        for i in range(4):
+            min_area_quad[i] = box[(first_point_idx + i) % 4]
+
+        bbox_new = min_area_quad.tolist()
+        bbox = []
+
+        for box in bbox_new:
+            box = list(map(int, box))
+            bbox.append(box)
+
+        return bbox
+
     def getImglabelidx(self, filePath):
         if platform.system() == 'Windows':
             spliter = '\\'
@@ -1965,7 +1997,11 @@ class MainWindow(QMainWindow):
             rec_flag = 0
             for shape in self.canvas.shapes:
                 box = [[int(p.x()), int(p.y())] for p in shape.points]
+
+                if len(box) > 4:
+                    box = self.gen_quad_from_poly(np.array(box))
                 assert len(box) == 4
+
                 img_crop = get_rotate_crop_image(img, np.array(box, np.float32))
                 if img_crop is None:
                     msg = 'Can not recognise the detection box in ' + self.filePath + '. Please change manually'
@@ -2014,6 +2050,8 @@ class MainWindow(QMainWindow):
         img = cv2.imread(self.filePath)
         for shape in self.canvas.selectedShapes:
             box = [[int(p.x()), int(p.y())] for p in shape.points]
+            if len(box) > 4:
+                box = self.gen_quad_from_poly(np.array(box))
             assert len(box) == 4
             img_crop = get_rotate_crop_image(img, np.array(box, np.float32))
             if img_crop is None:
diff --git a/PPOCRLabel/README.md b/PPOCRLabel/README.md
index 4d25e670ae6d07d569a247bc5f9c35c939b23f8e..9d5eea048350156957b0079e27a0239ae5e482e3 100644
--- a/PPOCRLabel/README.md
+++ b/PPOCRLabel/README.md
@@ -159,7 +159,7 @@ python PPOCRLabel.py --kie True # [KIE mode] for [detection + recognition + keyw
 | Ctrl + R                 | Re-recognize the selected box                    |
 | Ctrl + C                 | Copy and paste the selected box                  |
 | Ctrl + Left Mouse Button | Multi select the label box                       |
-| Alt + X                  | Delete the selected box                          |
+| Backspace                 | Delete the selected box                          |
 | Ctrl + V                 | Check image                                      |
 | Ctrl + Shift + d         | Delete image                                     |
 | D                        | Next image                                       |
diff --git a/PPOCRLabel/README_ch.md b/PPOCRLabel/README_ch.md
index 3f8dc4f0c6b7cc88a71409d123f598e74b3f2cad..a25871d9310d9c04a2f2fcbb68013938e26aa956 100644
--- a/PPOCRLabel/README_ch.md
+++ b/PPOCRLabel/README_ch.md
@@ -148,7 +148,7 @@ python PPOCRLabel.py --lang ch --kie True  # 启动 【KIE 模式】，用于打
 | Ctrl + R         | 重新识别所选标记            |
 | Ctrl + C         | 复制并粘贴选中的标记框       |
 | Ctrl + 鼠标左键    | 多选标记框                 |
-| Alt + X          | 删除所选框                 |
+| Backspace        | 删除所选框                 |
 | Ctrl + V         | 确认本张图片标记           |
 | Ctrl + Shift + d | 删除本张图片               |
 | D                | 下一张图片                |
diff --git a/PPOCRLabel/libs/canvas.py b/PPOCRLabel/libs/canvas.py
index 095fe5ab06553dcb05c8bcc061f950ded606ebb3..6c1043da43a5049f1c47f58152431259df9fa36a 100644
--- a/PPOCRLabel/libs/canvas.py
+++ b/PPOCRLabel/libs/canvas.py
@@ -263,7 +263,7 @@ class Canvas(QWidget):
                         if self.current.isClosed():
                             # print('1111')
                             self.finalise()
-                    elif self.drawSquare: # 增加
+                    elif self.drawSquare:
                         assert len(self.current.points) == 1
                         self.current.points = self.line.points
                         self.finalise()
diff --git a/PPOCRLabel/libs/shape.py b/PPOCRLabel/libs/shape.py
index fc8ab5ec4d7ff2836034d9c7e01acaf49dfe7aa0..18cc4a8e7692c2a88becca2e9ca19dfebbd61779 100644
--- a/PPOCRLabel/libs/shape.py
+++ b/PPOCRLabel/libs/shape.py
@@ -57,6 +57,7 @@ class Shape(object):
         self.locked = False
         self.direction = 0
         self.center = None
+        self.epsilon = 5  # same as canvas
         self._highlightIndex = None
         self._highlightMode = self.NEAR_VERTEX
         self._highlightSettings = {
@@ -98,11 +99,14 @@ class Shape(object):
         return False
 
     def addPoint(self, point):
-        if self.reachMaxPoints():
+        if self.reachMaxPoints() and self.closeEnough(self.points[0], point):
             self.close()
         else:
             self.points.append(point)
 
+    def closeEnough(self, p1, p2):
+        return distance(p1 - p2) < self.epsilon
+
     def popPoint(self):
         if self.points:
             return self.points.pop()