A non-transitory recording medium storing a plurality of instructions which, when executed by one or more processors, cause the processors to perform a method of processing a read image read by a reading part including a plurality of line image sensors, each of the line image sensors including reading elements arranged in line corresponding to pixels, the line image sensors being arranged in such a manner that one end parts of the line image sensors adjacent to each other are overlapped with each other in a direction perpendicular to a direction of alignment of the reading elements, comprising:
- detecting whether a density variation occurs for not less than a predetermined number of times or not in each of a plurality of regions in a seam-read image, the seam-read image being an image read by the reading elements present within a seam portion in which the line image sensors adjacent to each other are overlapped with each other;
- generating a seam image by synthesizing the seam-read images read by the line image sensors adjacent to each other in accordance with a detection result made in the detecting, the seam image being an image of the seam portion;
- and
- generating a read image corresponding to one line based on read images read by the line image sensors and the seam image.