Humans have always used their senses to assess the quality of products at the personal level or in the industry. For example, when buying fruit, people examine the fruit for the parameters they consider are important for assessing its quality such as colour, uniformity of colour, surface roughness, size, shape, surface defect. However, they are not able to assess internal damages or constituents of the fruit because their vision is limited to visible spectrum which is part of a vast electromagnetic spectra. Also, in industrial situations, assessment of objects can be affected by tiredness and fatigue of inspectors as well as different inspectors may assess the required quality parameters differently. Machine vision that involves collecting information from objects in visible or other spectra and analyzing the obtained information using image processing steps can assess the quality consistently over a long period as well as assess the internal and external quality parameters. With advances in high quality sensors (cameras) for different spectra, computing power of computers, and ease of developing software for a specific application, it has been possible to apply machine vision to many fields covered in this book.