PROJECTION DISPLAY DEVICE, PROJECTION DISPLAY METHOD, AND PROJECTION DISPLAY PROGRAM

A projection display device mounted in a vehicle includes a light modulation unit that spatially modulates, in accordance with image data that has been input, light emitted by a light source; a projection optical system that projects the light that has been spatially modulated onto a projection surface of the vehicle; and an image data control unit that controls image data to be input to the light modulation unit. The image data control unit performs, in a first mode in which driving is performed in accordance with an internally generated instruction or an externally and wirelessly received instruction, control to switch between projection of image light for normal display onto the projection surface and projection of image light for warning display onto the projection surface