论文中的sub-piexl子层实现

参照链接：https://github.com/tetrachrome/subpixel readme中有介绍

代码如下：

def _phase_shift(I, r):
	bsize, a, b, c = I.get_shape().as_list()
	bsize = tf.shape(I)[0] # Handling Dimension(None) type for undefined batch dim
	X = tf.reshape(I, (bsize, a, b, r, r))
	X = tf.transpose(X, (0, 1, 2, 4, 3))  # bsize, a, b, 1, 1
	X = tf.split(X, a, 1)  # a, [bsize, b, r, r]
	X = tf.concat([tf.squeeze(x, axis=1) for x in X],2)  # bsize, b, a*r, r
	X = tf.split(X, b, 1)  # b, [bsize, a*r, r]
	X = tf.concat([tf.squeeze(x, axis=1) for x in X],2)  # bsize, a*r, b*r
	return tf.reshape(X, (bsize, a*r, b*r, 1))

def PS(X, r, color=False):
	if color:
		Xc = tf.split(X, 3, 3)
		X = tf.concat([_phase_shift(x, r) for x in Xc],3)

	else:
		X = _phase_shift(X, r)
	return X