1. A notification control method executed by a computer, the notification control method comprising: acquiring image data of a displayable image from an imaging device which captures a capturing area, acquiring sensing data from an object detection sensor which detects an object within measuring area overlapping the capturing area; determining a visibility for the displayable image by generating a luminance histogram based on luminance information of the image data, and calculating a dynamic range in the luminance histogram to determine the visibility for the displayable image; and controlling a notification by a device to notify a detection of the object by the object detection sensor, in response to the dynamic range for the determined visibility for the displayable image being equal to or less than a threshold.