A method for forming an image sequence that is an output sequence, from an input image sequence, is provided. The input image sequence has an input spatial resolution and an input temporal resolution. The output sequence has an output temporal resolution equal to the input temporal resolution and an output spatial resolution equal to a predetermined fraction 1/N of the input spatial resolution by an integer number N higher than or equal to 2. The method, implemented for a sub-sequence of the input frame sequence that is a current input sub-sequence and including a preset number of images, includes: obtaining a temporal frequency that is an image frequency, associated with the current input sub-sequence; processing the current input sub-sequence to obtain an output sub-sequence; and inserting the output sub-sequence and the associated image frequency into an output container.