Patent ID: 8599257

Claim:
A vehicle detection device for detecting the presence or absence of a peripheral vehicle based on an image captured by an on-vehicle camera, comprising: computer hardware configured to include: a luminance creating unit operatively connected to an output of the on-vehicle camera and receiving the captured image, the luminance creating unit configured to create a luminance histogram of the captured image; a luminance threshold specifying unit operatively connected to an output of the luminance creating unit, the luminance threshold unit configured to i) analyze the luminance histogram of the captured image and ii) output a luminance value that a cumulative histogram value accumulated from a lower side of luminance of the luminance histogram that accounts for a predetermined percentage in a total number of pixels used for creating the luminance histogram as an upper limit for the luminance value; and a vehicle detecting unit operatively connected to an output of the luminance threshold specifying unit, the vehicle detecting unit i) deciding a vehicle assumed region which is a region assumed to include a vehicle bottom side having the luminance value not greater than the upper limit and ii) to determine whether or not the image of the vehicle assumed region corresponds to a vehicle by using a pattern matching method, wherein the luminance threshold specifying unit is configured i) to calculate the percentage based on a ratio of the number of pixels assumed to include the vehicle bottom region on a condition that the peripheral vehicle to be detected is captured in the largest size in the image and to the total number of pixels used for creating the luminance histogram, and ii) to adaptively determine the threshold in the luminance histogram, for the total number of pixels, and wherein the vehicle detecting unit determines the vehicle assumed region corresponds to the presence of the peripheral vehicle based on the vehicle assumed region pattern successfully matching a shadow area at the bottom side of the peripheral vehicle; a road surface region extracting unit, wherein, the road surface region extracting unit is configured to extract a road surface region from the captured image; and the luminance threshold specifying unit is configured to estimate and output an upper limit for a luminance value corresponding to the region of a vehicle bottom of a peripheral vehicle by analyzing the luminance histogram of the image created by the luminance creating unit within the road surface region extracted by the road surface region extracting unit.