An image synthesis system is disclosed for synthesizing a global shutter image based on a rolling shutter image. The rolling shutter image is captured by an aerial camera system having at least one rolling shutter camera and the rolling shutter image has a plurality of scanlines, the scanlines having associated different position and pose information. The image synthesis system is arranged to project a rolling shutter image captured by a rolling shutter camera to object space by projecting each scanline of the rolling shutter image using position and pose information associated with the scanline, and subsequently from object space to a synthetic global shutter image.