The invention discloses a method for extracting a maximally stable extremal region with
scale invariance. The method includes the steps that firstly, an initial maximally stable extremal region is detected in an original image through a maximally stable extremal region
algorithm; then a scale
pyramid of the initial maximally stable extremal region is built through M-scale
wavelet transform, characteristic points with the
scale invariance are determined in the scale
pyramid according to energy operators of an M-scale
wavelet transform coefficient, extremal regions corresponding to the characteristic points are obtained from all
layers of images of the scale
pyramid of the maximally stable extremal region, and the maximally stable extremal region with the
scale invariance is extracted through the stability indexes of the extremal region in a multi-
scale space; finally, the maximally stable extremal region with the scale invariance is adjusted to be in an oval shape, and the final maximally stable extremal region with the scale invariance is obtained. According to the method for extracting the maximally stable extremal region with the scale invariance, the scale invariance and the maximally stable extremal region are combined, the maximally stable extremal region is extracted, and full affine invariance is achieved.