1. A lane departure sensing method using a vehicle surrounding image, comprising: receiving images captured by a plurality of cameras installed to a car running, over respective channels connected to the cameras; generating a plurality of revised images by revising the captured images into a top-view; generating the vehicle surrounding image by synthesizing the plurality of the revised images; extracting a lane from the vehicle surrounding image, and determining lane departure by calculating distance information between the vehicle and the extracted lane or angle information formed by a moving direction of the vehicle and the extracted lane; and when determining the lane departure, issuing a warning, wherein the plurality of the revised images is generated using a look up table, wherein the generating of the vehicle surrounding image generates the vehicle surrounding image by overlaying the plurality of the revised images using a mask image which comprises region information per channel and weight information for pixels forming each region, wherein overlapping regions between the plurality of the revised images are overlay-processed using the following equation: 
 l ′( t+ 1)=α l 1 ( t )+(1−α) l 2 ( t ), 0≦α≦1 where l 1 (t) and l 2 (t) denote image information for the overlapping region input via two channels respectively, a denotes a weight for pixels in the overlapping region, and l′(t+1) denotes the overlay-processed image information, wherein the mask image is set to attain a Gradient weight for the pixels in the overlapping region, wherein the plurality of cameras include a front camera, a rear camera, a left camera and a right camera, wherein the front camera and the rear camera are installed such that their optical axis is parallel with the horizon, and the left camera and the right camera are installed perpendicularly to the ground, and wherein the mask image includes a first region duplicately captured through the front camera and the left camera of a vehicle, a third region duplicately captured through the front camera and the right camera of the vehicle, a seventh region duplicately captured through the rear camera and the left camera of the vehicle, a ninth region duplicately captured through the rear camera and the right camera of the vehicle, a second region captured through the front camera of the vehicle, without being duplicately captured through any other camera, a fourth region captured through the left camera of the vehicle, without being duplicately captured through any other camera, a sixth region captured through the right camera of the vehicle, without being duplicately captured through any other camera, an eighth region captured through the rear camera of the vehicle, without being duplicately captured through any other camera, and a fifth region on which an image corresponding to the vehicle is displayed.