Enable uniform augmentation magnitude sampling and set AugMix default

timm/data/auto_augment.py

@@ -332,13 +332,17 @@ class AugmentOp:
         # in the usually fixed policy and sample magnitude from a normal distribution
         # with mean `magnitude` and std-dev of `magnitude_std`.
         # NOTE This is my own hack, being tested, not in papers or reference impls.
+        # If magnitude_std is inf, we sample magnitude from a uniform distribution
         self.magnitude_std = self.hparams.get('magnitude_std', 0)
 
     def __call__(self, img):
         if self.prob < 1.0 and random.random() > self.prob:
             return img
         magnitude = self.magnitude
-        if self.magnitude_std and self.magnitude_std > 0:
+        if self.magnitude_std:
+            if self.magnitude_std == float('inf'):
+                magnitude = random.uniform(0, magnitude)
+            elif self.magnitude_std > 0:
                 magnitude = random.gauss(magnitude, self.magnitude_std)
         magnitude = min(_MAX_LEVEL, max(0, magnitude))  # clip to valid range
         level_args = self.level_fn(magnitude, self.hparams) if self.level_fn is not None else tuple()
@@ -790,6 +794,7 @@ def augment_and_mix_transform(config_str, hparams):
     depth = -1
     alpha = 1.
     blended = False
+    hparams['magnitude_std'] = float('inf')
     config = config_str.split('-')
     assert config[0] == 'augmix'
     config = config[1:]