Compare histogram features of image files

As a template for creation of image workflows was used xa-toolwrapper project from Sven Schlarb (https://github.com/openplanets/scape/tree/master/xa-toolwrapper). This project enables creation of WSDL web service that wraps command line tool like ‘extractFeatures’ or ‘create’. The workflow for ‘compare’ tool has three input parameters. These are two URLs to the XML histogram files that comprise information about image features. These files are acquired using ‘extractFeatures’ tool. The third parameter is an image histogram metric string for histogram comparison. Following metrics exist:
•    CV_COMP_CHISQRCV_COMP_CORREL
•    CV_COMP_INTERSECT
•    CV_COMP_BHATTACHARYYA.
This workflow extracts histogram features from passed image file. The output is an XML file with comparison result. Also the workflow provides output of processing log and return code (0 if successful).