Belt examination system and computer-readable non-transitory recording medium having stored belt examination program

A computer-readable non-transitory recording medium having stored thereon a belt examination program causing a computer to implement a defect candidate detecting processor that detects a candidate for a belt defect that is an abnormal portion of an intermediate transfer belt of an image forming apparatus from a belt image that is an image of the intermediate transfer belt, wherein

• the defect candidate detecting processor
• executes a background pattern reduction step to reduce a texture-pattern like background noise present in the belt image, and
• detects the candidate based on the belt image generated during the background pattern reduction step, and
• the background pattern reduction step is to replace, in the belt image, a color value within a specific range of color values not including a lowest color value of the belt defect with a specific color value within the specific range.