Raindrop sensor for detecting rain on a vehicle windshield including an image sensor and processor for performing a frequency analysis of an image and wiper controller having the same

A wiper controller for controlling a windshield wiper of a vehicle, the wiper controller comprising:

• capturing means for capturing an image of a windshield of the vehicle from inside the vehicle;
• high-frequency component determination means for performing a frequency analysis of the image and for determining based on a result of the frequency analysis whether the image has a high-frequency component;
• gradation change detection means that operates when the image has the high-frequency component to detect a width of a change region in which a rate of change in intensity of the image exceeds a predetermined threshold;
• raindrop determination means determining that the raindrop is on the windshield when the width of the change region is within a predetermined range corresponding to a diameter of the raindrop;
• control means for controlling the windshield wiper in accordance with an amount of the raindrop on the windshield;
• splash detection means for detecting water splashed on the windshield, wherein
• the splash detection means determines that the splashed water is on the windshield, when a first image captured at a first time has no high-frequency component, a second image captured at a second time subsequent to the first time has the high-frequency component, the second image includes at least two change regions, and the width of each of at least two of the at least two regions is outside the predetermined range, and
• the control means causes the windshield wiper to wipe the splashed water from the windshield when the splash detection means determines that the splashed water is on the windshield.