Quality inspection of logos by depth estimation

A finished product should be quality assured to meet the needs, expectations and requirements it is intended for. As quality through human inspection may lead to errors and may not be adequate for instant and mass production, current high speed production lines require automated inspection with precise critical objective measurements and high reliability. Image processing has become a key tool in the area of automated vision inspection for commercial marketability of finished goods utilizing devices for optical, non contact sensing to automatically receive and interpret an image of the product for integrity checking, correct labelling, surface finish, quality control, etc and has been used in many industries. In the soap industry, the company logo is engraved on the surface of the bar soap to a particular uniform depth which needs to be inspected against excess soap removal, non uniform engraving and absence of engraving. These defects of engraving lead to customer´s displeasure and thus a loss of business to the manufacturer. This paper presents an automated system using machine vision and image processing techniques to compute the depth at the engravement and to verify whether it meets the preset standards.