Disclosed herein are a method and an image processing apparatus implementing the method for determining a billing structure for outputting documents. The method determines if pixels of image data of a document in device independent space are neutral (e.g., gray) or non-neutral (e.g., color), and, based on at least the determined neutral pixels in device independent space, determines a billable pixel count of color pixels in the image data. In one example, the determined billable pixel count of color pixels is based on at least both an estimated color count in device independent space and a determined pixel count in device dependent space. In another, pixels are tagged based on the neutral and/or non-neutral determination in device independent space, and, if the tag indicates that a selected pixel is color in device dependent space, the selected pixel is counted for the billable pixel count.