1. A coefficient generating device that generates a conversion coefficient for converting an input image signal of an input image into a display image signal of a display image perceived by an observer as if the input image were displayed when the display image is displayed on predetermined display means, comprising: past-image generating means for generating a past image signal of a past image correlated with a teacher image of a frame that is one frame before a teacher image correlated with the display image, on the basis of a teacher image signal of the teacher image and a motion vector detected in the teacher image, the teacher image being used to obtain the conversion coefficient; transient-image generating means for generating, on the basis of the teacher image signal and the past image signal, in a case where the past image and then the teacher image are to be displayed on the display means, a transient image signal of a transient image to be displayed on the display means in a period in which displaying is switched from the past image to the teacher image; visual-image generating means for generating, using the past image signal, the transient image signal, the teacher image signal, and the motion vector, a visual image signal of a visual image perceived by the observer when the teacher image is displayed on the display means, the visual image serving as a student image correlated with the input image, the student image being used to obtain the conversion coefficient, by obtaining an average of pixel values of pixels in the past image, the transient image, and the teacher image, the pixels being predicted to be followed by eyes of the observer in the period in which displaying is switched from the past image to the teacher image, and regarding the average as a pixel value of a pixel in the visual image; and calculating means for obtaining the conversion coefficient using a pixel value of a pixel of interest in the teacher image and pixel values of pixels that are determined by a motion vector detected in the student image and that are spatially or temporally near a pixel in the student image that is at the same position as that of the pixel of interest.