The invention relates to an image processing method to generate, from a source image, an image of reduced size whose ratio between the width and the height is equal to a predetermined value, called reduced ratio. It comprises the following steps: selecting one rectangular image part in the source image, and extracting the rectangular image part to generate the reduced image. According to an essential characteristic of the method, if the ratio between the width and height of the rectangular image part, called first ratio, is not equal to the reduced ratio, the width or the height of the rectangular image part is modified before the extraction step according to values of perceptual interest associated with each pixel of the source image in such a manner that the ratio between the width and the height of the modified rectangular image part, called second ratio, is equal to the reduced ratio.