Then, Lab color space imag- es (i.e. Figs. 4(c) and 4(d)) of original image (i.e. Fig. 4(a)) and filter image Similar to the definition of gray-scale dilation, the gray-cess for saliency map (here, ‘disk’ type structuring elements is used to perform filter operation, the radius range of alter-scale erosion of S by structuring element e, denoted is defined as(i.e. Fig. 4(b)) are obtained by converting color space from RGB to Lab.