diff --git a/file_io/include/aare/FileInterface.h b/file_io/include/aare/FileInterface.h
index 3db9f6e..c718c84 100644
--- a/file_io/include/aare/FileInterface.h
+++ b/file_io/include/aare/FileInterface.h
@@ -20,6 +20,9 @@ public:
 
     // read n_frames frame into the provided buffer
     virtual void read_into(std::byte* image_buf, size_t n_frames) = 0; 
+
+    // size of one frame, important fro teh read_into function
+    virtual size_t bytes_per_frame() const = 0;
     
     // goto frame number
     virtual void seek(size_t frame_number) = 0;
@@ -30,6 +33,10 @@ public:
     // total number of frames in the file
     virtual size_t total_frames() = 0;
 
+    virtual size_t rows() const = 0;
+
+    virtual size_t cols() const = 0;
+
     virtual ~FileInterface() = 0;
 };
 } // namespace aare