--- a
+++ b/mmaction/datasets/image_dataset.py
@@ -0,0 +1,46 @@
+# Copyright (c) OpenMMLab. All rights reserved.
+from .builder import DATASETS
+from .video_dataset import VideoDataset
+
+
+@DATASETS.register_module()
+class ImageDataset(VideoDataset):
+    """Image dataset for action recognition, used in the Project OmniSource.
+
+    The dataset loads image list and apply specified transforms to return a
+    dict containing the image tensors and other information. For the
+    ImageDataset
+
+    The ann_file is a text file with multiple lines, and each line indicates
+    the image path and the image label, which are split with a whitespace.
+    Example of a annotation file:
+
+    .. code-block:: txt
+
+        path/to/image1.jpg 1
+        path/to/image2.jpg 1
+        path/to/image3.jpg 2
+        path/to/image4.jpg 2
+        path/to/image5.jpg 3
+        path/to/image6.jpg 3
+
+    Example of a multi-class annotation file:
+
+    .. code-block:: txt
+
+        path/to/image1.jpg 1 3 5
+        path/to/image2.jpg 1 2
+        path/to/image3.jpg 2
+        path/to/image4.jpg 2 4 6 8
+        path/to/image5.jpg 3
+        path/to/image6.jpg 3
+
+    Args:
+        ann_file (str): Path to the annotation file.
+        pipeline (list[dict | callable]): A sequence of data transforms.
+        **kwargs: Keyword arguments for ``BaseDataset``.
+    """
+
+    def __init__(self, ann_file, pipeline, **kwargs):
+        super().__init__(ann_file, pipeline, start_index=None, **kwargs)
+        # use `start_index=None` to indicate it is for `ImageDataset`