add ae sub folder

stylegan2_ae/layers/mini_batch_std.py

@@ -0,0 +1,33 @@
+import tensorflow as tf
+
+
+class MinibatchStd(tf.keras.layers.Layer):
+    def __init__(self, group_size, num_new_features, **kwargs):
+        super(MinibatchStd, self).__init__(**kwargs)
+        self.group_size = group_size
+        self.num_new_features = num_new_features
+
+    def call(self, inputs, training=None, mask=None):
+        s = tf.shape(inputs)
+        group_size = tf.minimum(self.group_size, s[0])
+
+        y = tf.reshape(inputs, [group_size, -1, self.num_new_features, s[1] // self.num_new_features, s[2], s[3]])
+        y = tf.cast(y, tf.float32)
+        y -= tf.reduce_mean(y, axis=0, keepdims=True)
+        y = tf.reduce_mean(tf.square(y), axis=0)
+        y = tf.sqrt(y + 1e-8)
+        y = tf.reduce_mean(y, axis=[2, 3, 4], keepdims=True)
+        y = tf.reduce_mean(y, axis=[2])
+        y = tf.cast(y, inputs.dtype)
+        y = tf.tile(y, [group_size, 1, s[2], s[3]])
+
+        x = tf.concat([inputs, y], axis=1)
+        return x
+
+    def get_config(self):
+        config = super(MinibatchStd, self).get_config()
+        config.update({
+            'group_size': self.group_size,
+            'num_new_features': self.num_new_features,
+        })
+        return config