Fixed offset of 0.5 pixels in sersic_xc and sersic_yc (does not affect the other Sersic parameters).

Author: vrodgom

notebooks/tutorial.ipynb

@@ -2302,7 +2302,7 @@ def _sersic_model(self):
 
         # Prepare data for fitting
         z = image.copy()
-        y, x = np.mgrid[0:ny, 0:nx]
+        y, x = np.mgrid[0:ny, 0:nx] + 0.5  # center of pixel
         weightmap = self._weightmap_stamp
         # Exclude pixels with image == 0 or weightmap == 0 from the fit.
         fit_weights = np.zeros_like(z)

statmorph/statmorph.py

@@ -15,38 +15,38 @@
 
 correct_values = {
     'xc_centroid':82.16578971349672,
-    'yc_centroid':81.0346179734321,
-    'ellipticity_centroid':0.04855709579575873,
-    'elongation_centroid':1.0510352177531561,
-    'orientation_centroid':-0.8579760206619491,
+    'yc_centroid':81.03461797343211,
+    'ellipticity_centroid':0.04855709579576,
+    'elongation_centroid':1.05103521775316,
+    'orientation_centroid':-0.85797602066195,
     'xc_asymmetry':82.23816149429084,
     'yc_asymmetry':80.76122537398356,
-    'ellipticity_asymmetry':0.04862719043000929,
-    'elongation_asymmetry':1.0511126552502466,
-    'orientation_asymmetry':-0.8590029492030308,
+    'ellipticity_asymmetry':0.04862719043001,
+    'elongation_asymmetry':1.05111265525025,
+    'orientation_asymmetry':-0.85900294920303,
     'rpetro_circ':40.93685686885102,
-    'rpetro_ellip':41.6568715935214,
+    'rpetro_ellip':41.65687159352140,
     'rhalf_circ':21.60432043808139,
-    'rhalf_ellip':22.092999181298023,
-    'r20':11.695409552661776,
+    'rhalf_ellip':22.09299918129802,
+    'r20':11.69540955266178,
     'r80':32.07888648441381,
-    'gini':0.3901765299814595,
-    'm20':-1.5429405756694308,
-    'gini_m20_bulge':-0.8493683576528599,
-    'sn_per_pixel':6.7997875,
-    'concentration':2.191019250473638,
-    'asymmetry':0.002168820096766045,
-    'smoothness':0.019515863990804592,
-    'sersic_amplitude':1296.9528812407366,
-    'sersic_rhalf':22.45788866708879,
-    'sersic_n':0.6120682828213252,
-    'sersic_xc':81.561975952764,
-    'sersic_yc':80.4046513562675,
-    'sersic_ellip':0.05083866210052884,
-    'sersic_theta':2.4783154293185397,
-    'sky_mean':3.487606,
-    'sky_median':-2.6854386,
-    'sky_sigma':150.91754,
+    'gini':0.39017652998146,
+    'm20':-1.54294057566943,
+    'gini_m20_bulge':-0.84936835765286,
+    'sn_per_pixel':6.79978752136230,
+    'concentration':2.19101925047364,
+    'asymmetry':0.00216882009677,
+    'smoothness':0.01951586399080,
+    'sersic_amplitude':1296.95301375647091,
+    'sersic_rhalf':22.45788881197317,
+    'sersic_n':0.61206811649601,
+    'sersic_xc':82.06197530371756,
+    'sersic_yc':80.90465047895643,
+    'sersic_ellip':0.05083868323144,
+    'sersic_theta':2.47831539294767,
+    'sky_mean':3.48760604858398,
+    'sky_median':-2.68543863296509,
+    'sky_sigma':150.91754150390625,
 }
 
 def test1():
@@ -62,10 +62,14 @@ def test1():
     source_morphs = statmorph.source_morphology(image, segmap, mask=mask, gain=gain)
     morph = source_morphs[0]
 
+    #for key in correct_values:
+    #    print("'%s':%.14f," % (key, morph[key]))
+
     # Check results
     assert morph['flag'] == 0
     assert morph['flag_sersic'] == 0
-    for key, value in correct_values.items():
+    for key in correct_values:
+        value = morph[key]
         value0 = correct_values[key]
         relative_error = np.abs((value - value0) / value0)
         assert relative_error < 1e-6