Abstract: An original image is pre-scanned, then scanning conditions to be used in main scanning are determined on the basis of obtained data in the pre-scanning. First, an original image is pre-scanned, and the obtained image signal is separated into color component signals. Thereafter, maximum values of the color component signals are detected for the respective colors. Further, the detected maximum values are analyzed to determine a type of the original image. After scanning conditions to be used in the main scanning are set on the basis of the type of the original image, the main scanning is performed.