A device, method, and program stored in a recording medium are provided. A sampling time period and, a value of limit angle are set. Inclination of the projector device is detected with respect to a horizontal surface to output a plurality of inclination angle values of the projector device. A representative angle value of a current sampling time period is calculated based on the plurality of inclination angle values and the difference between the representative angle value and a representative angle value from a previous sampling time period is calculated. It is determined whether the difference in representative angle value is equal to or greater than the limit angle value to generate a determination result. Finally, trapezoidal distortion in the image is corrected based on the inclination angle values detected when the determination result indicates that the difference is equal to or greater than the limit angle value.