1. An outside recognition apparatus configured to detect a raindrop on a lens of a camera, comprising: a control unit; and a memory coupled to the control unit, wherein the memory stores therein pixel value data of an image captured by the camera, and wherein the control unit is configured to: calculate image frequency powers of a plurality of frequency regions based on pixel values of a first region of a plurality of first regions of the image; determine whether each of the calculated image frequency powers of the plurality of frequency regions of the first region exceeds a predetermined first threshold; determine that the raindrop is in the first region if a number of the plurality of frequency regions in which the calculated image frequency powers does not exceed the first threshold value exceeds a predetermined second threshold; calculate image frequency powers based on pixel values of a plurality of second regions of the image each made of the plurality of the first regions, each of the plurality of second regions being smaller than the entire image; calculate image frequency powers based on pixel values of the plurality of first regions; determine presence or absence of the raindrop based on the calculated image frequency powers of the plurality of second regions and the calculated image frequency powers of the plurality of first regions; and output the determination that the raindrop is present or absent.