A neural network is provided to include a layer that has a weight set. The neural network is trained based on a first compression quality level, where the weight set and a first set of batch normalization coefficients are used in said layer, so the weight set and the first set of batch normalization coefficients are trained with respect to the first compression quality level. Then, the neural network is trained based on a second compression quality level, where the weight set that has been trained with respect to the first compression quality level and a second set of batch normalization coefficients are used in said layer, so the weight set is trained with respect to both of the first and second compression quality levels, and the second set of batch normalization coefficients is trained with respect to the second compression quality level. |