A method for discriminating a boundary of image, the method comprising: receiving a grayscale parameter value of each pixel unit from among an image information to be discriminated to form a matrix of grayscale parameter values, and dividing, with a grayscale parameter value corresponding to a pixel unit to be processed as a center of the matrix, the matrix of grayscale parameter values into a n × n matrix and a ( n + 2)×( n + 2) matrix, n representing a number of grayscale parameter values in a row direction or in a column direction, and n being an odd number greater than 1, the grayscale parameter being a luminance parameter or a chromaticity parameter, characterized by determining respectively in the n × n matrix and the ( n +2)×( n +2) matrix: a minimum gradient among a gradient in a row direction, a gradient in a column direction, a gradient in a first diagonal direction, and a gradient in a second diagonal direction, where the grayscale parameter value corresponding to the pixel unit to be processed resides; and a minimum standard deviation among a standard deviation in a row direction, a standard deviation in a column direction, a standard deviation in a first diagonal direction, and a standard deviation in a second diagonal direction, where the grayscale parameter value corresponding to the pixel unit to be processed resides; determining respectively in the n × n matrix and the ( n + 2)×( n + 2) matrix: dispersion of each of the standard deviation in the row direction, the standard deviation in the column direction, the standard deviation in the first diagonal direction, and the standard deviation in the second diagonal direction with respect to the minimum standard deviation; and dispersion of each of the gradient in the row direction, the gradient in the column direction, the gradient in the first diagonal direction, and the gradient in the second diagonal direction with respect to the minimum gradient; outputting, for each determined dispersion, a first code value when the determined dispersion is greater than N multiples of a minimum corresponding thereto, outputting a second code value when the determined dispersion is smaller than the N multiples of the minimum corresponding thereto, the minimum being the minimum standard deviation or the minimum gradient, N being a constant greater than 1; determining, based on the outputted code values, whether the image to be discriminated has a boundary and in which direction the boundary is. receiving a grayscale parameter value of each pixel unit from among an image information to be discriminated to form a matrix of grayscale parameter values, and dividing, with a grayscale parameter value corresponding to a pixel unit to be processed as a center of the matrix, the matrix of grayscale parameter values into a n × n matrix and a ( n + 2)×( n + 2) matrix, n representing a number of grayscale parameter values in a row direction or in a column direction, and n being an odd number greater than 1, the grayscale parameter being a luminance parameter or a chromaticity parameter, characterized by determining respectively in the n × n matrix and the ( n +2)×( n +2) matrix: a minimum gradient among a gradient in a row direction, a gradient in a column direction, a gradient in a first diagonal direction, and a gradient in a second diagonal direction, where the grayscale parameter value corresponding to the pixel unit to be processed resides; and a minimum standard deviation among a standard deviation in a row direction, a standard deviation in a column direction, a standard deviation in a first diagonal direction, and a standard deviation in a second diagonal direction, where the grayscale parameter value corresponding to the pixel unit to be processed resides; determining respectively in the n × n matrix and the ( n + 2)×( n + 2) matrix: dispersion of each of the standard deviation in the row direction, the standard deviation in the column direction, the standard deviation in the first diagonal direction, and the standard deviation in the second diagonal direction with respect to the minimum standard deviation; and dispersion of each of the gradient in the row direction, the gradient in the column direction, the gradient in the first diagonal direction, and the gradient in the second diagonal direction with respect to the minimum gradient; outputting, for each determined dispersion, a first code value when the determined dispersion is greater than N multiples of a minimum corresponding thereto, outputting a second code value when the determined dispersion is smaller than the N multiples of the minimum corresponding thereto, the minimum being the minimum standard deviation or the minimum gradient, N being a constant greater than 1; determining, based on the outputted code values, whether the image to be discriminated has a boundary and in which direction the boundary is.