New module for loading VEST lut files.

fsl/data/vest.py

+#!/usr/bin/env python
+#
+# vest.py - Functions for working with VEST files.
+#
+# Author: Paul McCarthy <pauldmccarthy@gmail.com>
+#
+"""This module contains a handful of functions for working with VEST files.
+
+.. autosummary::
+   :nosignatures:
+
+   looksLikeVestLutFile
+   loadVestLutFile
+"""
+
+
+import numpy as np
+
+
+def looksLikeVestLutFile(path):
+    """Returns ``True`` if the given ``path`` looks like a VEST LUT file,
+    ``False`` otherwise.
+    """
+    with open(path, 'rt') as f:
+        return f.readline().strip() == '%!VEST-LUT'
+
+
+def loadVestLutFile(path, normalise=True):
+    """Assumes that the given file is a VEST LUT file, and attempts to load it.
+
+    Returns a ``numpy.float32`` array of shape ``(n, 3)``, where ``n`` is the
+    number of colours in the file.
+
+    If ``normalise=True`` (the default), the colour values are normalised to
+    the range ``0-1``.
+    """
+
+    with open(path, 'rt') as f:
+        lines = f.readlines()
+
+    # We over-allocate the colour array
+    # here, and truncate the array after
+    # reading. idx keepsd track of the
+    # number of colours read in.
+    idx     = 0
+    colours = np.zeros((len(lines), 3), dtype=np.float32)
+
+    for line in lines:
+
+        if not line.startswith('<-color{'):
+            continue
+
+        start = line.index('{') + 1
+        end   = line.index('}')
+
+        r, g, b         = line[start:end].split(',')
+        colours[idx, :] = float(r), float(g), float(b)
+
+        idx += 1
+
+    colours = colours[:idx, :]
+
+    if normalise:
+        cmin = colours.min()
+        cmax = colours.max()
+        return (colours - cmin) / (cmax - cmin)
+    
+    else:
+        return colours