Fix RTDETR val_batch_pred (#3392)

ultralytics/vit/rtdetr/val.py

@@ -91,6 +91,7 @@ class RTDETRValidator(DetectionValidator):
         """Apply Non-maximum suppression to prediction outputs."""
         bs, _, nd = preds[0].shape
         bboxes, scores = preds[0].split((4, nd - 4), dim=-1)
+        bboxes *= self.args.imgsz
         outputs = [torch.zeros((0, 6), device=bboxes.device)] * bs
         for i, bbox in enumerate(bboxes):  # (300, 4)
             bbox = ops.xywh2xyxy(bbox)
@@ -126,8 +127,8 @@ class RTDETRValidator(DetectionValidator):
             if self.args.single_cls:
                 pred[:, 5] = 0
             predn = pred.clone()
-            predn[..., [0, 2]] *= shape[1]  # native-space pred
-            predn[..., [1, 3]] *= shape[0]  # native-space pred
+            predn[..., [0, 2]] *= shape[1] / self.args.imgsz  # native-space pred
+            predn[..., [1, 3]] *= shape[0] / self.args.imgsz  # native-space pred
 
             # Evaluate
             if nl: