Abstract: An image signal processing system, comprising a receiver, an addition block, and a transmitting block, is provided. The image signal processing system transmits a first image signal to a print block. The print block prints the rectangular image using the whole printable area. The aspect ratio of the rectangular image is a first aspect ratio. The receiver receives an original image signal corresponding to an original image. The aspect ratio of the original image is a second aspect ratio. The addition block generates a synthesized image signal corresponding to a synthesized image. The aspect ratio of the synthesized image is the first aspect ratio or nearer to the first aspect ratio than the second aspect ratio. The transmitting block transmits the synthesized image signal as the first image signal to the print block.