1. An image processing apparatus comprising: input means for inputting a luminance signal of each pixel of a multi-valued image; color attribute determination means for determining a color attribute of the pixel based on the luminance signal; storage means for storing the color attribute, determined by said color attribute determination means, with respect to pixels of a predetermined area including a pixel of interest; first counting means for counting an array attribute, determined in accordance with an array of the color attribute stored in said storage means, with respect to a second block having a predetermined number of lines in a first block, which is obtained by dividing a predetermined first line group of the multi-valued image in the main scanning direction; second counting means for counting with respect to the second block the color attribute determined by said color attribute determination means; calculation means for calculating a parameter, indicative of an image characteristic of the first block, based on counted values of said first and second counting means; block attribute determination means for determining an image attribute of the first block in accordance with the counted values of said first and second counting means and the parameter calculated by said calculation means; and line attribute determination means for determining an image attribute of the first line group based on a determination result of said block attribute determination means.