A learning method for learning parameters of convolutional neural network (CNN) by using multiple video frames is provided. The learning method includes steps of: (a) a learning device applying at least one convolutional operation to a (t-k)-th input image corresponding to a (t-k)-th frame and applying at least one convolutional operation to a t-th input image corresponding to a t-th frame following the (t-k)-th frame, to thereby obtain a (t-k)-th feature map corresponding to the (t-k)-th frame and a t-th feature map corresponding to the t-th frame; (b) the learning device calculating a first loss by referring to each of at least one distance value between each of pixels in the (t-k)-th feature map and each of pixels in the t-th feature map; and (c) the learning device backpropagating the first loss to thereby optimize at least one parameter of the CNN.