diff --git a/dlio_benchmark/reader/indexed_binary_mmap_reader.py b/dlio_benchmark/reader/indexed_binary_mmap_reader.py
index 92141c75..3e0313ef 100644
--- a/dlio_benchmark/reader/indexed_binary_mmap_reader.py
+++ b/dlio_benchmark/reader/indexed_binary_mmap_reader.py
@@ -104,6 +104,7 @@ def next(self):
     def read_index(self, image_idx, step):
         filename, sample_index = self.global_index_map[image_idx]
         self.get_sample(filename, sample_index)
+        self.preprocess()
         return self._args.resized_image
 
     @dlp.log