A method for generating a high quality up-scaled image includes: utilizing at least four pixels within a source image as reference pixels within the high quality up-scaled image, where the reference pixels are utilized as a portion of pixels within the high quality up-scaled image, and are utilized as reference for generating another portion of pixels within the high quality up-scaled image; and calculating at least one portion of three linear distribution values corresponding to three quarter points between two adjacent pixels of the reference pixels according to pixel values of the two adjacent pixels and adjusting the portion of the linear distribution values according to pixel values of at least three reference pixels of the four reference pixels, and generating at least one pixel within the high quality up-scaled image accordingly. An associated device is also provided.