1. A gesture recognition method with improved background suppression, the method comprising: sequentially capturing a plurality of images; calculating a position of at least one object in each of the plurality of images to respectively obtain a moving vector of the object at different times; calculating an average brightness and a size of the object in each of the plurality of images; and respectively adjusting magnitudes of the moving vectors of the object at the different times according to the average brightness and the size of the object in each of the plurality of images, wherein said adjusting comprises a weighting of the magnitudes of the moving vectors of the object at the different times, and said weighting is positively correlated to the average brightness and the size of the object in each of the plurality of images to cause the adjusted moving vectors of the object to be larger when the average brightness of the object is brighter and the size of the object is larger, and the adjusted moving vectors of the object to be smaller when the average brightness of the object is darker and the size of the object is smaller.