1. A processor-implemented method for processing image data comprising: 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, using the image processing apparatus comprising the following acts being implemented by the at least one processor: providing a billing structure comprising a plurality of original billing tiers defined by predetermined thresholds at which to bill image data; receiving image data of a document comprising a plurality of pixels including color pixels; determining pixel classifications of the color pixels for each pixel classification in the image data in device independent space; determining counts of the color pixels for each determined pixel classification in the image data in device independent space; classifying the image data as a whole into a category or class based on both of the determination of the pixel classifications and the determined counts; then converting the plurality of pixels of the image data into a plurality of pixels in device dependent space before determining counts of pixels for marking the image data; determining counts of color pixels in device dependent space for marking to output the image data; selecting one billing tier from the plurality of original billing tiers for which to bill the image data, and, then, after the selection of the one billing tier, adjusting from the selected one billing tier to a different billing tier for which to bill the image data using at least both of the category or class of the image data that is determined in device independent space and the determined counts of color pixels for marking determined in device dependent space, wherein the determined pixel classification and counts are determined by applying a neutral pixel determination algorithm and/or a neutral page determination algorithm to the image data in device independent space.