63fb46d6_bster_US___Patent_applications__Description
[Patent application number] 20130311403 [Published] 11-21-2013 [Description] 
CONTONE DOMAIN COLOR PIXEL COUNTING FOR COLOR AREA COVERAGE BASED BILLING - Disclosed herein are a method and a system implementing the method for billing using color pixel counting in documents or image in the contone domain. The method includes using the intensity or density levels (e.g., 0 to 255) for each color of each pixel of interest in the contone domain to calculate one or more probability values that one or more output colorants are provided at its location in the binary domain. The probabilities determined based on the contone color domain data are used to estimate an overall area coverage of color pixels in the document, which can be used to determine a billing structure or cost for outputting the document.
Xing Li, Webster US - Patent applications