diff --git a/discorpy/losa/loadersaver.py b/discorpy/losa/loadersaver.py
index 6fbaeb5..966d057 100644
--- a/discorpy/losa/loadersaver.py
+++ b/discorpy/losa/loadersaver.py
@@ -31,12 +31,14 @@
 
 """
 
+import json
 import platform
 from pathlib import Path
 import h5py
 import numpy as np
 from PIL import Image
 import matplotlib.pyplot as plt
+from matplotlib import font_manager
 from collections import OrderedDict
 
 
@@ -422,8 +424,7 @@ def save_image(file_path, mat, overwrite=True):
     str
         Updated file path.
     """
-    file_path = __get_path(file_path, check_exist=False)
-    file_path = file_path.resolve()
+    file_path = __get_path(file_path, check_exist=False).resolve()
     file_ext = file_path.suffix
     if not ((file_ext == ".tif") or (file_ext == ".tiff")):
         if mat.dtype != np.uint8:
@@ -494,8 +495,29 @@ def save_plot_image(file_path, list_lines, height, width, overwrite=True,
     return file_path
 
 
+def __check_font(font_family):
+    """
+    Check if a specific font is available in Matplotlib.
+
+    Parameters
+    ----------
+    font_family : str
+        Name of the font to check.
+
+    Returns
+    -------
+    bool
+        True if font is available, False otherwise.
+    """
+    try:
+        font_manager.findfont(font_family, fallback_to_default=False)
+        return True
+    except:
+        return False
+
+
 def save_residual_plot(file_path, list_data, height, width, overwrite=True,
-                       dpi=100):
+                       dpi=100, font_family='Times New Roman'):
     """
     Save the plot of residual against radius to an image. Useful to check the
     accuracy of unwarping results.
@@ -514,6 +536,8 @@ def save_residual_plot(file_path, list_data, height, width, overwrite=True,
         Overwrite the existing file if True.
     dpi : int, optional
         The resolution in dots per inch.
+    font_family : str, optional
+        To set the font family
 
     Returns
     -------
@@ -528,7 +552,8 @@ def save_residual_plot(file_path, list_data, height, width, overwrite=True,
     fig.set_size_inches(width / dpi, height / dpi)
     m_size = 0.5 * min(height / dpi, width / dpi)
     plt.rc('font', size=np.int16(m_size * 4))
-    plt.rcParams['font.family'] = 'Times New Roman'
+    if __check_font(font_family):
+        plt.rcParams['font.family'] = font_family
     plt.rcParams['font.weight'] = 'bold'
     plt.xlabel('Radius', fontweight='bold')
     plt.ylabel('Residual', fontweight='bold')
@@ -562,8 +587,7 @@ def save_hdf_file(file_path, idata, key_path='entry', overwrite=True):
     str
         Updated file path.
     """
-    file_path = __get_path(file_path, check_exist=False)
-    file_path = file_path.resolve()
+    file_path = __get_path(file_path, check_exist=False).resolve()
     if file_path.suffix.lower() not in {'.hdf', '.h5', '.nxs', '.hdf5'}:
         file_path = file_path.with_suffix('.hdf')
     _create_folder(str(file_path))
@@ -605,8 +629,7 @@ def open_hdf_stream(file_path, data_shape, key_path='entry/data',
     object
         hdf object.
     """
-    file_path = __get_path(file_path, check_exist=False)
-    file_path = file_path.resolve()
+    file_path = __get_path(file_path, check_exist=False).resolve()
     if file_path.suffix.lower() not in {'.hdf', '.h5', '.nxs', '.hdf5'}:
         file_path = file_path.with_suffix('.hdf')
     _create_folder(str(file_path))
@@ -631,6 +654,60 @@ def open_hdf_stream(file_path, data_shape, key_path='entry/data',
     return data_out
 
 
+def save_plot_points(file_path, list_points, height, width, overwrite=True,
+                     dpi=100, marker="o", color="blue"):
+    """
+    Save the plot of dot-centroids to an image. Useful to check if the dots
+    are arranged properly where dots on the same line having the same color.
+
+    Parameters
+    ----------
+    file_path : str
+        Output file path.
+    list_points : list of 1D-array
+        List of the (y-x)-coordinates of points.
+    height : int
+        Height of the image.
+    width : int
+        Width of the image.
+    overwrite : bool, optional
+        Overwrite the existing file if True.
+    dpi : int, optional
+        The resolution in dots per inch.
+    marker : str
+        Plot marker. Full list is at:
+        https://matplotlib.org/stable/api/markers_api.html
+    color : str
+        Marker color. Full list is at:
+        https://matplotlib.org/stable/tutorials/colors/colors.html
+
+    Returns
+    -------
+    str
+        Updated file path.
+    """
+    file_path = __get_path(file_path, check_exist=False).resolve()
+    _create_folder(str(file_path))
+    if not overwrite:
+        file_path = _create_file_name(str(file_path))
+    fig = plt.figure(frameon=False)
+    fig.set_size_inches(width / dpi, height / dpi)
+    ax = plt.Axes(fig, [0., 0., 1.0, 1.0])
+    ax.set_axis_off()
+    fig.add_axes(ax)
+    plt.axis((0, width, 0, height))
+    m_size = 0.5 * min(height / dpi, width / dpi)
+    for point in list_points:
+        plt.plot(point[1], height - point[0], marker, color=color,
+                 markersize=m_size)
+    try:
+        plt.savefig(file_path, dpi=dpi)
+    except IOError:
+        raise ValueError("Couldn't write to file {}".format(file_path))
+    plt.close()
+    return file_path
+
+
 def save_metadata_txt(file_path, xcenter, ycenter, list_fact, overwrite=True):
     """
     Write metadata to a text file.
@@ -653,8 +730,7 @@ def save_metadata_txt(file_path, xcenter, ycenter, list_fact, overwrite=True):
     str
         Updated file path.
     """
-    file_path = __get_path(file_path, check_exist=False)
-    file_path = file_path.resolve()
+    file_path = __get_path(file_path, check_exist=False).resolve()
     if file_path.suffix.lower() not in {'.txt', '.dat'}:
         file_path = file_path.with_suffix('.txt')
     _create_folder(str(file_path))
@@ -698,56 +774,78 @@ def load_metadata_txt(file_path):
     return xcenter, ycenter, list_fact
 
 
-def save_plot_points(file_path, list_points, height, width, overwrite=True,
-                     dpi=100, marker="o", color="blue"):
+def __numpy_encoder(obj):
+    if isinstance(obj, (np.int_, np.intc, np.intp, np.int8,
+                        np.int16, np.int32, np.int64, np.uint8,
+                        np.uint16, np.uint32, np.uint64)):
+        return int(obj)
+    elif isinstance(obj, (np.float_, np.float16, np.float32, np.float64)):
+        return float(obj)
+    elif isinstance(obj, (np.ndarray,)):
+        return obj.tolist()
+    raise TypeError(f"Object of type '{type(obj).__name__}' "
+                    f"is not JSON serializable")
+
+
+def save_metadata_json(file_path, xcenter, ycenter, list_fact, overwrite=True):
     """
-    Save the plot of dot-centroids to an image. Useful to check if the dots
-    are arranged properly where dots on the same line having the same color.
+    Write metadata to a JSON file.
 
     Parameters
     ----------
     file_path : str
         Output file path.
-    list_points : list of 1D-array
-        List of the (y-x)-coordinates of points.
-    height : int
-        Height of the image.
-    width : int
-        Width of the image.
+    xcenter : float
+        Center of distortion in x-direction.
+    ycenter : float
+        Center of distortion in y-direction.
+    list_fact : list of float
+        Coefficients of a polynomial.
     overwrite : bool, optional
-        Overwrite the existing file if True.
-    dpi : int, optional
-        The resolution in dots per inch.
-    marker : str
-        Plot marker. Full list is at:
-        https://matplotlib.org/stable/api/markers_api.html
-    color : str
-        Marker color. Full list is at:
-        https://matplotlib.org/stable/tutorials/colors/colors.html
+        Overwrite an existing file if True.
 
     Returns
     -------
     str
         Updated file path.
     """
-    file_path = __get_path(file_path, check_exist=False)
-    file_path = file_path.resolve()
+    # Get resolved file path and set to JSON suffix
+    file_path = __get_path(file_path, check_exist=False).resolve()
+    if file_path.suffix.lower() != '.json':
+        file_path = file_path.with_suffix('.json')
     _create_folder(str(file_path))
+
     if not overwrite:
         file_path = _create_file_name(str(file_path))
-    fig = plt.figure(frameon=False)
-    fig.set_size_inches(width / dpi, height / dpi)
-    ax = plt.Axes(fig, [0., 0., 1.0, 1.0])
-    ax.set_axis_off()
-    fig.add_axes(ax)
-    plt.axis((0, width, 0, height))
-    m_size = 0.5 * min(height / dpi, width / dpi)
-    for point in list_points:
-        plt.plot(point[1], height - point[0], marker, color=color,
-                 markersize=m_size)
-    try:
-        plt.savefig(file_path, dpi=dpi)
-    except IOError:
-        raise ValueError("Couldn't write to file {}".format(file_path))
-    plt.close()
+
+    # Create metadata dictionary
+    metadata = {
+        'xcenter': float(xcenter),
+        'ycenter': float(ycenter),
+        'list_fact': list_fact
+    }
+    with open(file_path, "w") as f:
+        json.dump(metadata, f, indent=4, default=__numpy_encoder)
     return file_path
+
+
+def load_metadata_json(file_path):
+    """
+    Load distortion coefficients from a JSON file.
+
+    Parameters
+    ----------
+    file_path : str
+        Path to a JSON file.
+
+    Returns
+    -------
+    tuple of floats and list
+        Tuple of (xcenter, ycenter, list_fact).
+    """
+    with open(__get_path(file_path), 'r') as f:
+        metadata = json.load(f)
+    xcenter = metadata['xcenter']
+    ycenter = metadata['ycenter']
+    list_fact = metadata['list_fact']
+    return xcenter, ycenter, list_fact
diff --git a/examples/example_01.py b/examples/example_01.py
index 2c101ae..5076bf8 100644
--- a/examples/example_01.py
+++ b/examples/example_01.py
@@ -167,6 +167,8 @@
               np.abs(corrected_mat - mat0))
 io.save_metadata_txt(output_base + "/coefficients_bw.txt", xcenter, ycenter,
                      list_fact)
+# io.save_metadata_json(output_base + "/coefficients_bw.json", xcenter, ycenter,
+#                      list_fact)
 
 # Check the correction results
 list_uhor_lines = post.unwarp_line_backward(list_hor_lines, xcenter, ycenter,
@@ -205,6 +207,8 @@
               np.abs(corrected_mat - mat0))
 io.save_metadata_txt(output_base + "coefficients_fw.txt", xcenter, ycenter,
                      list_fact)
+# io.save_metadata_json(output_base + "coefficients_fw.json", xcenter, ycenter,
+#                      list_fact)
 
 # Check the correction results
 list_uhor_lines = post.unwarp_line_forward(list_hor_lines, xcenter, ycenter,
@@ -247,6 +251,8 @@
               np.abs(corrected_mat - mat0))
 io.save_metadata_txt(
     output_base + "/coefficients_bwfw.txt", xcenter, ycenter, list_bfact)
+# io.save_metadata_json(
+#     output_base + "/coefficients_bwfw.json", xcenter, ycenter, list_bfact)
 # Check the correction results
 list_uhor_lines = post.unwarp_line_backward(
     list_hor_lines, xcenter, ycenter, list_bfact)
diff --git a/tests/test_loadersaver.py b/tests/test_loadersaver.py
index 35b83b3..4d7cbc5 100644
--- a/tests/test_loadersaver.py
+++ b/tests/test_loadersaver.py
@@ -239,6 +239,19 @@ def test_open_hdf_stream(self):
         self.assertRaises(ValueError, f_alias, "./tmp/data/data4.hdf",
                           (64, 64), options={"energy/entry/data": 25.0})
 
+    def test_save_plot_points(self):
+        f_alias = losa.save_plot_points
+        list_data = np.ones((64, 2), dtype=np.float32)
+        file_path = "./tmp/data/plot1.png"
+        list_data[:, 0] = 0.5 * np.random.rand(64)
+        list_data[:, 1] = np.arange(64)
+        f_alias(file_path, list_data, 64, 64, dpi=100)
+        self.assertTrue(os.path.isfile(file_path))
+
+        path = f_alias(file_path, list_data, 64, 64,
+                       dpi=100, overwrite=False)
+        self.assertTrue(os.path.isfile(path))
+
     def test_save_metadata_txt(self):
         f_alias = losa.save_metadata_txt
         file_path = "./tmp/data/coef.txt"
@@ -253,21 +266,26 @@ def test_save_metadata_txt(self):
         self.assertTrue(os.path.isfile(file_path + ".txt"))
 
     def test_load_metadata_txt(self):
-        f_alias = losa.load_metadata_txt
         file_path = "./tmp/data/coef1.txt"
         losa.save_metadata_txt(file_path, 31.0, 32.0, [1.0, 0.0])
-        (x, y, facts) = f_alias(file_path)
+        (x, y, facts) = losa.load_metadata_txt(file_path)
         self.assertTrue(((x == 31.0) and (y == 32.0)) and facts == [1.0, 0.0])
 
-    def test_save_plot_points(self):
-        f_alias = losa.save_plot_points
-        list_data = np.ones((64, 2), dtype=np.float32)
-        file_path = "./tmp/data/plot1.png"
-        list_data[:, 0] = 0.5 * np.random.rand(64)
-        list_data[:, 1] = np.arange(64)
-        f_alias(file_path, list_data, 64, 64, dpi=100)
+    def test_save_metadata_json(self):
+        f_alias = losa.save_metadata_json
+        file_path = "./tmp/data/coef.json"
+        f_alias(file_path, 31, 32, [1.0, 0.0])
         self.assertTrue(os.path.isfile(file_path))
 
-        path = f_alias(file_path, list_data, 64, 64,
-                       dpi=100, overwrite=False)
-        self.assertTrue(os.path.isfile(path))
+        path = f_alias(file_path, 31, 32, [1.0, 0.0], overwrite=False)
+        self.assertTrue(path != file_path)
+
+        file_path_no_ext = "./tmp/data/coef1"
+        f_alias(file_path_no_ext, 31, 32, [1.0, 0.0])
+        self.assertTrue(os.path.isfile(file_path_no_ext + ".json"))
+
+    def test_load_metadata_json(self):
+        file_path = "./tmp/data/coef1.json"
+        losa.save_metadata_json(file_path, 31.0, 32.0, [1.0, 0.0])
+        x, y, facts = losa.load_metadata_json(file_path)
+        self.assertTrue((x == 31.0) and (y == 32.0) and facts == [1.0, 0.0])