[Fix] Fix image_demo.py error (#1640)

* [Fix] Fix image_demo.py error

* [Fix] Fix image_demo.py error

* fix

* delete plt.cla()

demo/image_demo.py

@@ -10,6 +10,7 @@ def main():
     parser.add_argument('img', help='Image file')
     parser.add_argument('config', help='Config file')
     parser.add_argument('checkpoint', help='Checkpoint file')
+    parser.add_argument('--out-file', default=None, help='Path to output file')
     parser.add_argument(
         '--device', default='cuda:0', help='Device used for inference')
     parser.add_argument(
@@ -33,7 +34,8 @@ def main():
         args.img,
         result,
         get_palette(args.palette),
-        opacity=args.opacity)
+        opacity=args.opacity,
+        out_file=args.out_file)
 
 
 if __name__ == '__main__':

docs/en/get_started.md

@@ -80,7 +80,7 @@ The downloading will take several seconds or more, depending on your network env
 Option (a). If you install mmsegmentation from source, just run the following command.
 
 ```shell
-python demo/image_demo.py demo/demo.jpg pspnet_r50-d8_512x1024_40k_cityscapes.py pspnet_r50-d8_512x1024_40k_cityscapes_20200605_003338-2966598c.pth --device cpu --out-file result.jpg
+python demo/image_demo.py demo/demo.png configs/pspnet/pspnet_r50-d8_512x1024_40k_cityscapes.py pspnet_r50-d8_512x1024_40k_cityscapes_20200605_003338-2966598c.pth --device cuda:0 --out-file result.jpg
 ```
 
 You will see a new image `result.jpg` on your current folder, where segmentation masks are covered on all objects.

mmseg/apis/inference.py

@@ -106,7 +106,8 @@ def show_result_pyplot(model,
                        fig_size=(15, 10),
                        opacity=0.5,
                        title='',
-                       block=True):
+                       block=True,
+                       out_file=None):
     """Visualize the segmentation results on the image.
 
     Args:
@@ -124,6 +125,8 @@ def show_result_pyplot(model,
             Default is ''.
         block (bool): Whether to block the pyplot figure.
             Default is True.
+        out_file (str or None): The path to write the image.
+            Default: None.
     """
     if hasattr(model, 'module'):
         model = model.module
@@ -134,3 +137,5 @@ def show_result_pyplot(model,
     plt.title(title)
     plt.tight_layout()
     plt.show(block=block)
+    if out_file is not None:
+        mmcv.imwrite(img, out_file)