diff --git a/hardware-specific-tests/picamera2/test_tuning.py b/hardware-specific-tests/picamera2/test_tuning.py
index d2733b8f..6d58d8e6 100644
--- a/hardware-specific-tests/picamera2/test_tuning.py
+++ b/hardware-specific-tests/picamera2/test_tuning.py
@@ -1,7 +1,5 @@
 """Tests that check that a tuning file can be reloaded."""
 
-import os
-
 import pytest
 from picamera2 import Picamera2
 
@@ -24,24 +22,6 @@ def generate_bad_tuning():
     return bad_tuning
 
 
-def print_tuning(read_file: bool = False):
-    """Print the path of the default tuning file from the the environment variable.
-
-    :param read_file: Boolean, set true to also print the file contents.
-
-    This is useful for debugging. As pytest suppresses the printing by default the
-    -s option is needed when running pytest to see this.
-    """
-    key = "LIBCAMERA_RPI_TUNING_FILE"
-    if key in os.environ:
-        print(f"Tuning file environment variable: {os.environ[key]}")
-        if read_file:
-            with open(os.environ[key], "r") as f:
-                print(f.read())
-    else:
-        print("Tuning file environment variable not set")
-
-
 def _test_bad_tuning_after_good_tuning(configure: bool = False):
     """Test loading good, bad, then another good tuning files in sequence.
 
@@ -56,10 +36,8 @@ def _test_bad_tuning_after_good_tuning(configure: bool = False):
     """
     bad_tuning = generate_bad_tuning()
     default_tuning = tf_utils.load_default_tuning("imx219")
-    print_tuning()
     print("opening camera with default tuning")
     with Picamera2(tuning=default_tuning) as cam:
-        print_tuning()
         if configure:
             cam.configure(cam.create_preview_configuration())
     del cam
diff --git a/src/openflexure_microscope_server/things/camera/picamera.py b/src/openflexure_microscope_server/things/camera/picamera.py
index 9cee3856..95eb06e5 100644
--- a/src/openflexure_microscope_server/things/camera/picamera.py
+++ b/src/openflexure_microscope_server/things/camera/picamera.py
@@ -706,7 +706,7 @@ class StreamingPiCamera2(BaseCamera):
         It is a 9 value tuple used to specify the 3x3 matrix that the GPU pipeline uses
         to convert from the camera R,G,B vector to the standard R,G,B.
         """
-        return tuple(tf_utils.get_ccm(self.tuning)[0]["ccm"])
+        return tuple(tf_utils.get_ccm(self.tuning))
 
     @colour_correction_matrix.setter  # type: ignore
     def colour_correction_matrix(
diff --git a/src/openflexure_microscope_server/things/camera/picamera_tuning_file_utils.py b/src/openflexure_microscope_server/things/camera/picamera_tuning_file_utils.py
index 20f2d7a1..991296dc 100644
--- a/src/openflexure_microscope_server/things/camera/picamera_tuning_file_utils.py
+++ b/src/openflexure_microscope_server/things/camera/picamera_tuning_file_utils.py
@@ -73,11 +73,20 @@ def find_tuning_algo(tuning: dict[str, dict], name: str) -> dict[str, Any]:
     # Version 1 of the tuning files was simply a dictionary of algorithms. Later
     # versions have an "algorithms" key, the value of which is a list of algorithms.
     if version == 1:
-        return tuning[name]
+        try:
+            return tuning[name]
+        except KeyError as e:
+            raise KeyError(f"No algorithm {name} in tuning.") from e
+
     # The tuning file "algorithms" is a list of dictionaries
+    if "algorithms" not in tuning:
+        raise KeyError("A v2 tuning file must specify an algorithms key")
     algorithms = tuning["algorithms"]
     # The list is a list of dictionaries that have 1 key: the algorithm name
-    algo_dict = next(algo for algo in algorithms if name in algo)
+    try:
+        algo_dict = next(algo for algo in algorithms if name in algo)
+    except StopIteration as e:
+        raise KeyError(f"No algorithm {name} in tuning.") from e
     # We want the value for that key, which is a dictionary of algorithm parameters
     return algo_dict[name]
 
@@ -183,9 +192,7 @@ def lst_calibrated(tuning: dict) -> bool:
 
 def set_ccm(
     tuning: dict,
-    col_corr_matrix: tuple[
-        float, float, float, float, float, float, float, float, float
-    ],
+    col_corr_matrix: list,
 ) -> dict:
     """Update the ``rpi.alsc`` section of a camera tuning dict set the colour correction matrix.
 
@@ -194,15 +201,17 @@ def set_ccm(
     :return: an updated tuning dict with the new colour correction matrix.
     """
     output_tuning = deepcopy(tuning)
+    if len(col_corr_matrix) != 9:
+        raise ValueError("col_corr_matrix should be a list of 9 floats")
     ccm = find_tuning_algo(output_tuning, "rpi.ccm")
-    ccm["ccms"] = [{"ct": CALIBRATED_COLOUR_TEMP, "ccm": col_corr_matrix}]
+    ccm["ccms"] = [{"ct": CALIBRATED_COLOUR_TEMP, "ccm": list(col_corr_matrix)}]
     return output_tuning
 
 
 def get_ccm(tuning: dict) -> None:
     """Get a copy of the the ``rpi.ccm`` section of a camera tuning dict."""
     ccm = find_tuning_algo(tuning, "rpi.ccm")
-    return deepcopy(ccm["ccms"])
+    return deepcopy(ccm["ccms"][0]["ccm"])
 
 
 def set_static_geq(
diff --git a/tests/test_cameras.py b/tests/test_cameras.py
index 307df610..fc10370b 100644
--- a/tests/test_cameras.py
+++ b/tests/test_cameras.py
@@ -112,7 +112,6 @@ def test_thing_description_equivalence(mock_picam_thing):
     # defined as PiCamera specific, or by replicating the functionality for other
     # cameras.
     picamera_extra_actions = {
-        "flat_lens_shading_chrominance",
         "set_static_green_equalisation",
         "set_ce_enable_to_off",
         "stop_streaming",
@@ -130,6 +129,7 @@ def test_thing_description_equivalence(mock_picam_thing):
         "sensor_modes",
         "sensor_mode",
     }
+    # Note these are only the action not exposed as calibration actions.
     for action in picamera_extra_actions:
         assert action in picamera_actions
     for props in picamera_extra_props:
diff --git a/tests/test_picamera_tuning_files.py b/tests/test_picamera_tuning_files.py
new file mode 100644
index 00000000..cb2ea8a6
--- /dev/null
+++ b/tests/test_picamera_tuning_files.py
@@ -0,0 +1,258 @@
+"""Tests for interactions with tuning files and dictionaries."""
+
+from copy import deepcopy
+
+import pytest
+import numpy as np
+
+
+from openflexure_microscope_server.things.camera import (
+    picamera_tuning_file_utils as tf_utils,
+)
+
+RNG = np.random.default_rng()
+
+
+@pytest.fixture
+def imx219_tuning():
+    """Load the default tuning file for the PiCamera v2."""
+    return tf_utils.load_default_tuning("imx219")
+
+
+@pytest.fixture
+def imx477_tuning():
+    """Load the default tuning file for the PiCamera HQ."""
+    return tf_utils.load_default_tuning("imx477")
+
+
+def test_load_tuning(imx219_tuning, imx477_tuning):
+    """Check the sctandard tuning files load and contain the correct information."""
+    assert imx219_tuning != imx477_tuning
+
+    for tuning in [imx219_tuning, imx477_tuning]:
+        assert tuning["version"] == 2.0
+        assert tuning["target"] == "bcm2835"
+        assert isinstance(tuning["algorithms"], list)
+
+    # The algorithms in order, and whether we expect them to be the same for the cameras.
+    algos = [
+        ("rpi.black_level", True),
+        ("rpi.dpc", True),
+        ("rpi.lux", True),
+        ("rpi.noise", True),
+        ("rpi.geq", True),
+        ("rpi.sdn", True),
+        ("rpi.awb", True),
+        ("rpi.agc", True),
+        ("rpi.alsc", True),
+        ("rpi.contrast", True),
+        ("rpi.ccm", False),
+        ("rpi.sharpen", True),
+        ("rpi.hdr", True),
+        ("rpi.sync", True),
+    ]
+
+    # Strict= true so this will error if the tuning files are not the same length as
+    # the algorithms
+    zipped_algos = zip(
+        algos, imx219_tuning["algorithms"], imx477_tuning["algorithms"], strict=True
+    )
+
+    # Split up the algorithm name, either we expect them to be the same in both files
+    # and the algorithm for the two tuning files.
+    for (algo_name, algo_same), algo219, algo477 in zipped_algos:
+        # Check this is the correct algorithm
+        assert algo_name in algo219
+        assert algo_name in algo477
+        # Check they are they are the same if expected to be.
+        if algo_same:
+            assert algo219 == algo477
+        else:
+            assert algo219 != algo477
+
+
+def test_find_tuning_algo_v1():
+    """Check tuning algorithms are read directly from dict if no version is set."""
+    # Version 1 onf the tuning file was just a dictionary of algorithms
+    mock_tuning = {"mock": {"param": 1}, "foo": {"param": "bar"}}
+    assert tf_utils.find_tuning_algo(mock_tuning, "mock") == {"param": 1}
+    assert tf_utils.find_tuning_algo(mock_tuning, "foo") == {"param": "bar"}
+    with pytest.raises(KeyError, match="No algorithm who in tuning."):
+        assert tf_utils.find_tuning_algo(mock_tuning, "who")
+
+    # Also check that if version is not 1 it is read differently.
+    mock_tuning["version"] = 2
+    with pytest.raises(KeyError, match="A v2 tuning file must specify"):
+        assert tf_utils.find_tuning_algo(mock_tuning, "mock")
+
+
+def test_find_tuning_algo_v2():
+    """Check reading version 2 dictionary structure."""
+    mock_tuning = {
+        "version": 2.0,
+        "algorithms": [{"mock": {"param": 1}}, {"foo": {"param": "bar"}}],
+    }
+    assert tf_utils.find_tuning_algo(mock_tuning, "mock") == {"param": 1}
+    assert tf_utils.find_tuning_algo(mock_tuning, "foo") == {"param": "bar"}
+    with pytest.raises(KeyError, match="No algorithm who in tuning."):
+        assert tf_utils.find_tuning_algo(mock_tuning, "who")
+
+
+def _assert_lst_table_equivalence(array, table):
+    """Check equivalence between input numpy array and output table."""
+    for i in range(12):
+        for j in range(16):
+            assert table[i][j] == round(float(array[i, j]), 3)
+            assert table[i][j] == round(float(array[i, j]), 3)
+
+
+def test_tuning_lst_tools(imx219_tuning, imx477_tuning):
+    """Check reading the default lens shading tables."""
+    for tuning in (imx219_tuning, imx477_tuning):
+        assert not tf_utils.lst_calibrated(tuning)
+
+        lst_model = tf_utils.get_lst(tuning)
+        assert isinstance(lst_model, tf_utils.LensShading)
+        # Check the tables are lists of lists
+        assert isinstance(lst_model.luminance, list)
+        assert isinstance(lst_model.luminance[0], list)
+        assert isinstance(lst_model.Cr, list)
+        assert isinstance(lst_model.Cr[0], list)
+        assert isinstance(lst_model.Cb, list)
+        assert isinstance(lst_model.Cb[0], list)
+        # Loaded table has default lens tuning,
+        assert lst_model.colour_temp == tf_utils.DEFAULT_COLOUR_TEMP
+
+
+def test_setting_lst(imx219_tuning):
+    """Check that the LST can be set."""
+    lum = RNG.normal(size=(12, 16))
+    cr = RNG.normal(size=(12, 16))
+    cb = RNG.normal(size=(12, 16))
+
+    updated_tuning = tf_utils.set_lst(
+        imx219_tuning,
+        luminance=lum,
+        cr=cr,
+        cb=cb,
+        colour_temp=tf_utils.CALIBRATED_COLOUR_TEMP,
+    )
+
+    # Check it wasn't modified in place.
+    assert updated_tuning != imx219_tuning
+    # Check it now reports as calibrated
+    assert tf_utils.lst_calibrated(updated_tuning)
+
+    lst_model = tf_utils.get_lst(updated_tuning)
+    assert lst_model.colour_temp == tf_utils.CALIBRATED_COLOUR_TEMP
+    # Check the numbers are equivalent from the input array and the output table
+    # except for formatting and rounding.
+    _assert_lst_table_equivalence(lum, lst_model.luminance)
+    _assert_lst_table_equivalence(cr, lst_model.Cr)
+    _assert_lst_table_equivalence(cb, lst_model.Cb)
+
+    # Flatten the lens shading tables
+    flat_tuning = tf_utils.flatten_lst(updated_tuning)
+    # In this case only the colour channels
+    flat_chroma_tuning = tf_utils.flatten_lst(updated_tuning, keep_luminance=True)
+
+    # Check each was changed
+    assert updated_tuning != flat_tuning
+    assert updated_tuning != flat_chroma_tuning
+    assert flat_tuning != flat_chroma_tuning
+
+    # Check the flattened tunings report as not calibrated
+    assert not tf_utils.lst_calibrated(flat_tuning)
+    assert not tf_utils.lst_calibrated(flat_chroma_tuning)
+
+    flat_lst_model = tf_utils.get_lst(flat_tuning)
+    flat_chroma_lst_model = tf_utils.get_lst(flat_chroma_tuning)
+
+    flat_array = np.ones((12, 16))
+
+    # Check the that it really was flattened for the flat tuning
+    _assert_lst_table_equivalence(flat_array, flat_lst_model.luminance)
+    _assert_lst_table_equivalence(flat_array, flat_lst_model.Cr)
+    _assert_lst_table_equivalence(flat_array, flat_lst_model.Cb)
+
+    # Check only colour channels flattened when keep_luminance=True
+    _assert_lst_table_equivalence(lum, flat_chroma_lst_model.luminance)
+    _assert_lst_table_equivalence(flat_array, flat_chroma_lst_model.Cr)
+    _assert_lst_table_equivalence(flat_array, flat_chroma_lst_model.Cb)
+
+
+def test_setting_ccm(imx219_tuning):
+    """Check the colour correction matrix can be set."""
+    # CCM is set as a flat list. Create a mock ccm
+    new_ccm = [1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0]
+
+    updated_tuning = tf_utils.set_ccm(imx219_tuning, new_ccm)
+
+    # Check it wasn't modified in place.
+    assert updated_tuning != imx219_tuning
+
+    # Check the value was set
+    assert tf_utils.get_ccm(updated_tuning) == new_ccm
+
+    # Check that our dictionary doesn't update if the input list is updated.
+    new_ccm[0] = 0.0
+    assert tf_utils.get_ccm(updated_tuning) != new_ccm
+
+    new_ccm.append(1.0)
+    with pytest.raises(
+        ValueError, match="col_corr_matrix should be a list of 9 floats"
+    ):
+        tf_utils.set_ccm(imx219_tuning, new_ccm)
+
+
+def test_green_equalisation(imx219_tuning):
+    """Test setting the offset parameter of green equalisation."""
+    assert tf_utils.geq_is_static(imx219_tuning)
+    bad_geq_tuning = tf_utils.set_static_geq(imx219_tuning, offset=1234)
+    # Check it wasn't modified in place.
+    assert bad_geq_tuning != imx219_tuning
+
+    # No longer static
+    assert not tf_utils.geq_is_static(bad_geq_tuning)
+
+    fixed_geq_tuning = tf_utils.set_static_geq(bad_geq_tuning)
+
+    assert tf_utils.geq_is_static(fixed_geq_tuning)
+
+
+def test_ce_enable(imx219_tuning):
+    """Check the setting of ce enable in the contrast algorithm."""
+    assert tf_utils.ce_enable_is_static(imx219_tuning)
+
+    # No way to enable it so do it manually
+    bad_tuning = deepcopy(imx219_tuning)
+    contrast = tf_utils.find_tuning_algo(bad_tuning, "rpi.contrast")
+    contrast["ce_enable"] = 1
+
+    assert not tf_utils.ce_enable_is_static(bad_tuning)
+
+    fixed_tuning = tf_utils.set_ce_to_disabled(bad_tuning)
+    assert tf_utils.ce_enable_is_static(fixed_tuning)
+
+
+def test_copying_algorithms(imx219_tuning):
+    """Check an algorithm can be copied from one file to another."""
+    # Update the CCM
+    new_ccm = [1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0]
+    updated_ccm_tuning = tf_utils.set_ccm(imx219_tuning, new_ccm)
+    # It has changed
+    assert updated_ccm_tuning != imx219_tuning
+
+    # Create another tuning file with the GEQ updated.
+    updated_geq_tuning = tf_utils.set_static_geq(imx219_tuning, offset=1234)
+    # It has changed
+    assert updated_geq_tuning != imx219_tuning
+
+    # Copy the CCM from the dict with the bad GEQ value into the one with the updated
+    # CCM
+    original_tuning = tf_utils.copy_algo_from_other_tuning(
+        "rpi.ccm", base_tuning_file=updated_ccm_tuning, copy_from=updated_geq_tuning
+    )
+
+    # This should now be equivalent to the original.
+    assert original_tuning == imx219_tuning