[Fix] Fix mmseg.api.inference inference_segmentor (#1849)

* [Fix] Fix mmseg.api.inference inference_segmentor

Motivation
Fix inference_segmentor not working with multiple images path or images. List[str/ndarray]

Modification
- process images if instance is list

* fix typo

* Update mmseg/apis/inference.py

Co-authored-by: Hakjin Lee <nijkah@gmail.com>

Co-authored-by: Hakjin Lee <nijkah@gmail.com>

mmseg/apis/inference.py

@@ -67,7 +67,7 @@ def __call__(self, results):
         return results
 
 
-def inference_segmentor(model, img):
+def inference_segmentor(model, imgs):
     """Inference image(s) with the segmentor.
 
     Args:
@@ -84,9 +84,13 @@ def inference_segmentor(model, img):
     test_pipeline = [LoadImage()] + cfg.data.test.pipeline[1:]
     test_pipeline = Compose(test_pipeline)
     # prepare data
-    data = dict(img=img)
-    data = test_pipeline(data)
-    data = collate([data], samples_per_gpu=1)
+    data = []
+    imgs = imgs if isinstance(imgs, list) else [imgs]
+    for img in imgs:
+        img_data = dict(img=img)
+        img_data = test_pipeline(img_data)
+        data.append(img_data)
+    data = collate(data, samples_per_gpu=len(imgs))
     if next(model.parameters()).is_cuda:
         # scatter to specified GPU
         data = scatter(data, [device])[0]