diff --git a/conda/meta.yaml b/conda/meta.yaml
index e33d45b..8ca46d1 100644
--- a/conda/meta.yaml
+++ b/conda/meta.yaml
@@ -14,8 +14,8 @@ requirements:
     - setuptools
     - wheel
     - jinja2 >=2.11.0
-    - pip
-    
+    - pip    
+
   run:
     - python
     - numpy>=1.22.0
diff --git a/ismrmrd/constants.py b/ismrmrd/constants.py
index 451be1d..e22aef5 100644
--- a/ismrmrd/constants.py
+++ b/ismrmrd/constants.py
@@ -68,6 +68,7 @@
 IMTYPE_REAL      = 3
 IMTYPE_IMAG      = 4
 IMTYPE_COMPLEX   = 5
+IMTYPE_RGB       = 6
 
 # Image flags
 IMAGE_IS_NAVIGATION_DATA  =  1
diff --git a/ismrmrd/hdf5.py b/ismrmrd/hdf5.py
index f391128..f0eb5ee 100644
--- a/ismrmrd/hdf5.py
+++ b/ismrmrd/hdf5.py
@@ -144,12 +144,15 @@ def fileinfo(fname):
 
 
 class Dataset(object):
-    def __init__(self, filename, dataset_name="dataset", create_if_needed=True):
+    def __init__(self, filename, dataset_name="dataset", create_if_needed=True, mode=None):
         # Open the file
-        if create_if_needed:
-            self._file = h5py.File(filename, 'a')
-        else:
-            self._file = h5py.File(filename, 'r+')
+        if mode is None:
+            if create_if_needed:
+                mode = 'a'
+            else:
+                mode = 'r+'
+
+        self._file = h5py.File(filename, mode)
 
         self._dataset_name = dataset_name
 
diff --git a/ismrmrd/waveform.py b/ismrmrd/waveform.py
index f128ffa..936f47f 100644
--- a/ismrmrd/waveform.py
+++ b/ismrmrd/waveform.py
@@ -69,6 +69,9 @@ def from_array(data, **kwargs):
 
         channels, nsamples = data.shape
 
+        if nsamples > np.iinfo(np.uint16).max:
+            raise TypeError(f"Array has {nsamples} samples, which is greater than the maximum of {np.iinfo(np.uint16).max}")
+
         array_data = {
             'version': 1,
             'channels': channels,
diff --git a/tests/test_file.py b/tests/test_file.py
index 9bbc8d4..01e72b9 100644
--- a/tests/test_file.py
+++ b/tests/test_file.py
@@ -401,6 +401,20 @@ def test_file_can_rewrite_data_and_images():
         imageset.images = random_images(2)
         imageset.images = random_images(3)
 
+@nose.tools.with_setup(create_temp_dir, delete_temp_dir)
+def test_dataset_context_manager():
+
+    filename = os.path.join(temp_dir, "acquisitions.h5")
+    
+    acq = create_random_acquisition(1)
+
+    with ismrmrd.Dataset(filename) as dataset:
+        dataset.append_acquisition(acq)
+
+    with ismrmrd.Dataset(filename) as dataset:
+        assert dataset.number_of_acquisitions() > 0
+        assert not (dataset.read_acquisition(0) is None)
+
 
 example_header = """<?xml version="1.0" encoding="utf-8"?>
 <ismrmrdHeader xmlns="http://www.ismrm.org/ISMRMRD" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.ismrm.org/ISMRMRD ismrmrd.xsd">