Defect Inspection Using Machine Vision Systems

Visual defect inspection is an important part of quality assurance. Consumers rely heavily on appearance to choose quality products. Machine vision systems can automate the task of identifying and measuring visible defects. Using machine vision systems, manufacturers are able to objectively monitor product quality parameters and measure the benefits of improved production techniques.

Visual product quality is important to consumers. The consumer has the choice between many competing products, and appearance is often a key issue in deciding which product to purchase. Where the product itself cannot be visually inspected before purchase, consumers will be disappointed if the product found inside the packaging does not compare well with the images displayed on the packaging.

Traditionally, visual quality product parameters have been assessed by trained human inspectors. However, human inspectors are limited in their ability to perform objective, consistent and high speed inspection. They are prone to fatigue, and inspection performance varies over time and between individuals. Human inspection is also affected by environmental factors.

Machine Vision Systems for Defect Inspection

Machine vision systems use computational algorithms that give consistent results time after time. Quality measurements made by machine vision systems can be used to monitor quality changes over periods of years, ensuring that a company's reputation is maintained and enhanced.

Identification of broken blister defects in baked goods using colour segmentation.

Where individual product items have identical appearance, defects can be detected by template matching techniques. In this approach, the machine vision system compares product samples with a template--a digital picture of what the product should look like. Differences between the template and the image of a particular product sample are classified to identify the type of defect.

Many products, however, require more flexible machine vision techniques. Food products, for example, rarely appear identical to a template. For these products, a segmentation approach is used where visible defects are separated from acceptable product based on colour or shape properties of the defect. Visual defects in baked goods and fresh produce may often be identified by their colour properties.

Where 100% inspection is required, machine vision systems provide the capability to visually inspect product at rates far greater than is possible by other means. On-line machine vision inspection systems continuously monitor product for specified quality parameters such as shape, dimensions and colour.

Hamey Vision Systems can assist you to develop a visual inspection system to monitor visual defects that are important for your products. Whatever approach you need, our expertise can provide a solution for your visual defect inspection task. Contact us to find out how we can help you.

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