Change phase range in field mapping calculations (#499)

* Change from 0 to 2pi to -pi to pi * small fixes --------- Co-authored-by: Alexandre D'Astous <po09i@hotmail.com>
shimming-toolbox · Jan 4, 2024 · d86c825 · d86c825
1 parent 67c4cf1
commit d86c825
Showing 1 changed file with 4 additions and 6 deletions.
diff --git a/shimmingtoolbox/load_nifti.py b/shimmingtoolbox/load_nifti.py
@@ -181,13 +181,11 @@ def read_nii(fname_nifti, auto_scale=True):
             extent = (np.amax(image) - np.amin(image))
 
             if np.amin(image) < 0 and (0.95 * 2 * PHASE_SCALING_SIEMENS < extent < 2 * PHASE_SCALING_SIEMENS * 1.05):
-                # Siemens' scaling: [-4096, 4095] --> [-pi, pi)
-                image = image * math.pi / PHASE_SCALING_SIEMENS
+                # Siemens' scaling: [-4096, 4095] --> [-pi, pi[
+                image = (image * math.pi / PHASE_SCALING_SIEMENS)
             elif np.amin(image) >= 0 and (0.95 * PHASE_SCALING_SIEMENS < extent < PHASE_SCALING_SIEMENS * 1.05):
-                # Siemens' scaling [0, 4095] --> [0, 2pi)
-                # We want: [-pi, pi]
-                image = image * 2 * math.pi / PHASE_SCALING_SIEMENS
-                image = np.angle(np.exp(1j * image))
+                # Siemens' scaling [0, 4095] --> [-pi, pi[
+                image = (image * 2 * math.pi / PHASE_SCALING_SIEMENS) - math.pi
             else:
                 logger.info("Could not scale phase data")