Method for automatically drawing two-dimensional color pencil drawings

The invention relates to a method for automatically drawing two-dimensional color pencil drawings. The method comprises the steps that firstly, gradient information of an input image is calculated with regard to a brightness channel (I) under HSI color space to generate a gradient vector field, and a white noise image is generated in the brightness channel (I) according to brightness information of the input image; then, vector information of current pixel points of the input image is utilized for generating pencil filter operators of the current pixel points; a convolution operation is performed on the pixel points of the pencil filter operators and the pixel points of the white noise image to obtain a black and white pencil drawing sketch; color information of color channels (H and S) of the input image is added into the black and white pencil drawing sketch; the color space is converted to generate a colorized pencil drawing sketch in RGB color space; image fusion is performed between the input image with