Image data on which image processing has already been performed is obtained with a digital camera. Image processing information includes information indicating a photography mode set at the digital camera. Tag information including the image processing information is attached to the image data. If the image processing information includes information indicating a night view mode, an image output device judges whether the night view mode was intentionally set by a user by judging whether photography date/time information included in the tag information represents night. If the judgment is YES, the image output device sets an output image processing means not to perform exposure correction processing. If the judgment is NO, the image output device sets the output image processing means to perform regular processing including the exposure correction processing.