1. An image inspection method, comprising: obtaining a read image, the read image including a pre-provided image previously provided on a recording sheet and an output target image formed on the recording sheet having the pre-provided image; obtaining a pre-provided inspection image; obtaining an output target inspection image based on the output target image of the read image; obtaining a threshold value indicating an allowable range of offset differences between the output target inspection image and the pre-provided inspection image, with respect to the minimum offset difference obtained at a reference position at which the output target inspection image and the pre-provided inspection image are superimposed; obtaining an output target image positional shift indicating a positional shift between the output target image in the read image and the output target inspection image; obtaining a pre-provided image positional shift indicating a positional shift between the pre-provided image in the read image and the pre-provided inspection image; comparing a relative value of the output target image positional shift with respect to the pre-provided image positional shift, with the threshold value, to generate a determination result indicating whether the output target image and the pre-provided image in the read image overlap; and inspecting the read image using the output target inspection image and the pre-provided inspection image based on the determination result.