import tensorflow as tf

		crop_h = h//self.crop_factor
		crop_w = w//self.crop_factor
		rgb = tf.image.random_crop(rgb,size=[crop_h,crop_w,c])

		# cast, bit conversion, compress domain, center
		rgb = tf.cast(rgb, tf.float32)
		if n_bits < 8:
			rgb = tf.floor(rgb/(2**(8-n_bits)))
		rgb = rgb/(n_bins) - 0.5

