Fixed Test error when encoder(image).

When we load an image for the sample, we have to make sure that the image has three color channel (RGB) because it might be grayscale. So we should convert it for sampling.

tutorials/03-advanced/image_captioning/sample.py

@@ -14,7 +14,7 @@ from PIL import Image
 device = torch.device('cuda' if torch.cuda.is_available() else 'cpu')
 
 def load_image(image_path, transform=None):
-    image = Image.open(image_path)
+    image = Image.open(image_path).convert('RGB')
     image = image.resize([224, 224], Image.LANCZOS)
     
     if transform is not None:
@@ -78,4 +78,4 @@ if __name__ == '__main__':
     parser.add_argument('--hidden_size', type=int , default=512, help='dimension of lstm hidden states')
     parser.add_argument('--num_layers', type=int , default=1, help='number of layers in lstm')
     args = parser.parse_args()
-    main(args)
+    main(args)