1 23 Food and Bioprocess Technology An International Journal ISSN 1935-5130 Food Bioprocess Technol DOI 10.1007/s11947-013-1219-0 Edge Detection Features to Evaluate Hardness of Dates Using Monochrome Images A. Manickavasagan, H. N. Al-Shekaili, G. Thomas, M. S. Rahman, N. Guizani & D. S. Jayas