Colour Measurement using Digital Imaging

Accurate colour measurement is possible with digital imaging systems. New techniques provide the necessary precise calibration of digital cameras for machine vision systems. Applications include colour matching, colour inspection and surface defect inspection.

Accurate colour measurement has usually relied upon instruments such as colorimeters. Colorimeters measure colour accurately over a sample area--the measurement indicates the "average" colour over the sample area. When the sample has colour variations within it, important information is lost when a colorimeter is used.

Simulated colorimeter response--average colour over sample area.

True image data used by digital imaging system.

A colorimeter measures average colour but a digital imaging system gives detailed information.

In contrast, a digital imaging system records the colour at thousands, or even millions, of points in the sample--each pixel records a separate colour measurement. This provides much more detailed information about the colour of the sample. The camera must be calibrated to provide accurate data. With calibration, a digital image can be used to measure not only the average colour, but also the colour distribution within the sample. This allows a machine vision system to more accurately classify objects using detailed colour information.

Applications of Imaging Colour Measurement Systems

Calibrated imaging systems have been successfully used for colour inspection. Hamey Vision Systems has developed colour inspection systems for biscuit colour inspection and timber colour matching. Accurate colour measurement is also useful for defect inspection systems.

Hamey Vision Systems are experienced in using digital imaging systems for accurate colour measurement. Contact us to find out how we can help you with your colour measurement application.

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