Imaging device having an image mode set according to a filter

An imaging device including a lens group configured to form an object image, and an imaging sensor configured to convert the formed object image to an image signal, the imaging device comprising:

• one or more processors;
• and
• memory storing instructions that, when executed by the one or more processors, cause the imaging device to perform operations including:
• inserting and removing a plurality of optical filters to and from the lens group,
• setting one of a first imaging mode, a second imaging mode, and a third imaging mode,
• performing noise reduction processing on the image signal according to a set imaging mode,
• switching a threshold based on the set imaging mode,
• comparing an illuminance value of the image signal with the threshold to produce a comparison result, and
• switching, based on the comparison result, two of the following:
• the first imaging mode, the second imaging mode, and the third imaging mode,
• wherein the plurality of optical filters includes:
• a first filter having a transmittance of a wavelength component in an infrared region that is smaller than a transmittance of a wavelength component in a visible region, and
• a second filter having a transmittance of the wavelength component in the infrared region that is larger than the transmittance of the wavelength component in the visible region, and
• wherein the first imaging mode inserts the first filter into the lens group, the second imaging mode inserts the second filter into the lens group, and the third imaging mode removes the first filter and the second filter from the lens group.