Image reading device, image inspection device, and image forming apparatus

An image reading device comprising:

• a reader configured to read a pattern formed on a medium;
• a first background part disposed opposite the reader via a conveyance passage of the medium;
• a second background part disposed opposite the reader via the conveyance passage of the medium and having a higher light reflectance than a light reflectance of the first background part;
• and
• circuitry configured to move one of the first background part and the second background part to a facing position at which the one of the first background part and the second background part faces the reader via the conveyance passage of the medium,
• the circuitry configured to:
• move the first background part to the facing position in a case in which the pattern is a light color and the medium is transparent;
• and
• move the second background part to the facing position in a case in which the pattern is a dark color darker than the light color or the medium is not transparent.