Optimal error metric function for motion estimation is determined and used for video coding and/or video processing of images. To do so, an initial motion estimation using an initial error metric function can be performed. This can produce motion prediction errors. If the initial error metric function is not the optimal error function, then a final motion estimation is performed using a selected optimal error metric function. In some embodiments, a shape of error distribution can be used to determine the optimal error metric function. Some example systems or devices for this motion estimation can include systems or devices for compression, temporal interpolation, and/or super-resolution processing.