1. A processor-implemented method for color pixel counting in documents for billing comprising at least one page using an image processing apparatus, the image processing apparatus comprising at least one processor for processing documents containing image data comprising a plurality of pixels, the method comprising the following acts implemented by the at least one processor: receiving image data of a document comprising a plurality of pixels; determining a billable count of color pixels in the received image data by establishing windows in the image data comprising M rows and N columns of pixels, and, for each window: calculating an area coverage of color pixels by counting a number of pixels with at least one color plane ON; performing color detection by counting a number of ON pixels in each color plane; determining if the window is color or neutral based on at least the counts of ON pixels in each color plane, and if the window is determined as color, adding the count of the number of pixels from the area coverage calculation to the billable count of color pixels, else, adding the count of the number of pixels from the area coverage calculation to a neutral pixel count.