Add note on random selection of magnitude value

Author: rwightman

timm/data/auto_augment.py

@@ -251,18 +251,22 @@ def __init__(self, name, prob, magnitude, hparams={}):
         self.level_fn = level_to_arg(hparams)[name]
         self.prob = prob
         self.magnitude = magnitude
+        # If std deviation of magnitude is > 0, we introduce some randomness
+        # in the usually fixed policy and sample magnitude from normal dist
+        # with mean magnitude and std-dev of magnitude_std.
+        # NOTE This is being tested as it's not in paper or reference impl.
+        self.magnitude_std = 0.5  # FIXME add arg/hparam
         self.kwargs = {
             'fillcolor': hparams['img_mean'] if 'img_mean' in hparams else _FILL,
             'resample': hparams['interpolation'] if 'interpolation' in hparams else _RANDOM_INTERPOLATION
         }
-        self.rand_magnitude = True
 
     def __call__(self, img):
         if self.prob < random.random():
             return img
         magnitude = self.magnitude
-        if self.rand_magnitude:
-            magnitude = random.normalvariate(magnitude, 0.5)
+        if self.magnitude_std and self.magnitude_std > 0:
+            magnitude = random.gauss(magnitude, self.magnitude_std)
         magnitude = min(_MAX_LEVEL, max(0, magnitude))
         level_args = self.level_fn(magnitude)
         return self.aug_fn(img, *level_args, **self.kwargs)