diff --git a/face_rec.py b/face_rec.py
index 6f208a2..7dbfbfa 100644
--- a/face_rec.py
+++ b/face_rec.py
@@ -160,7 +160,7 @@ class FaceRecognitionSystem:
             self.screen_height = screen.height
             self.logger.info(f"屏幕尺寸已缓存: {self.screen_width}x{self.screen_height}")
         except Exception as e:
-            self.logger.debug(f"无法获取屏幕尺寸，使用默认尺寸: {e}")
+            self.logger.warning(f"无法获取屏幕尺寸，使用默认尺寸 1920x1080: {e}")
 
     def _force_cleanup_ffmpeg(self):
         """强制清理所有FFmpeg相关资源 - 防止多进程推流"""
@@ -689,17 +689,19 @@ class FaceRecognitionSystem:
                 self.logger.error(f"无法读取二维码图片: {self.qrcode_image_path}")
                 return False
 
+            # 获取二维码图片尺寸
+            qr_height, qr_width = qr_image.shape[:2]
+
+            # 使用屏幕缓存尺寸，如果获取失败则使用图片尺寸
+            canvas_width = self.screen_width if self.screen_width > 0 else qr_width
+            canvas_height = self.screen_height if self.screen_height > 0 else qr_height
+
             # 创建二维码窗口
             cv2.namedWindow(self.qrcode_window_name, cv2.WINDOW_NORMAL | cv2.WINDOW_GUI_NORMAL)
 
-            # 使用缓存的屏幕尺寸
-            canvas_width = self.screen_width
-            canvas_height = self.screen_height
             x_pos = 0
             y_pos = 0
 
-            qr_height, qr_width = qr_image.shape[:2]
-
             rendered = self._build_qrcode_instruction_canvas(qr_image, (canvas_width, canvas_height))
             if rendered is None:
                 # 回退到原二维码展示
@@ -710,14 +712,13 @@ class FaceRecognitionSystem:
                 new_height = int(qr_height * scale)
                 resized_qr = cv2.resize(qr_image, (new_width, new_height), interpolation=cv2.INTER_LINEAR)
                 
-                # 创建黑色背景画布，完全填充屏幕
+                # 创建背景画布
                 rendered = np.zeros((canvas_height, canvas_width, 3), dtype=np.uint8)
                 
                 # 计算居中位置
                 x_offset = (canvas_width - new_width) // 2
                 y_offset = (canvas_height - new_height) // 2
                 
-                # 将二维码放在中央
                 rendered[y_offset:y_offset+new_height, x_offset:x_offset+new_width] = resized_qr
 
             cv2.resizeWindow(self.qrcode_window_name, canvas_width, canvas_height)