Added function to normalise image pixel values.

remotesensinginfo · Jul 14, 2024 · 0aa8ab0 · 0aa8ab0
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diff --git a/doc/python/source/rsgislib_tools_stats.rst b/doc/python/source/rsgislib_tools_stats.rst
@@ -4,6 +4,7 @@ RSGISLib Stats Tools
 Normalisation
 ----------------
 .. autofunction:: rsgislib.tools.stats.standarise_img_data
+.. autofunction:: rsgislib.tools.stats.normalise_img_data
 
 
 Histogram Thresholds

diff --git a/python/rsgislib/tools/stats.py b/python/rsgislib/tools/stats.py
@@ -1217,3 +1217,22 @@ def standarise_img_data(img_data: numpy.array) -> numpy.array:
     std_img_data = numpy.reshape(std_img_data, (img_bands, img_height, img_width))
 
     return std_img_data
+
+
+def normalise_img_data(img_data: numpy.array) -> numpy.array:
+    """
+    Normalise the input image (data - min)/range.
+
+    :param img_data: a numpy array with the shape [bands, height, width]
+    :return: a numpy array with the normalised pixel values.
+
+    """
+    img_bands, img_height, img_width = img_data.shape
+    img_data_reshp = numpy.reshape(img_data, (img_bands, img_height * img_width))
+    max_value = numpy.max(img_data_reshp, axis=1, keepdims=True)
+    min_value = numpy.min(img_data_reshp, axis=1, keepdims=True)
+    diff_value = max_value - min_value
+    nm_img = (img_data_reshp - min_value) / diff_value
+    nm_img = numpy.reshape(nm_img, (img_bands, img_height, img_width))
+
+    return nm_img