A method and apparatus for providing objective assessment of pain using a field portable device is described. In the method, clusters of corrupted symbols in a stream of symbols are characterized in accordance with a cluster parameter associated with the clusters. A first sensor element for each of the basic colors is used to generate pixel values of odd pixels of rows on the original, and a second sensor element for each of the basic colors is used to generate pixel values of even pixels of rows of the original. There are correlations among the data.