Using machine vision for real-time, feedback control of seasoning content
Maintaining a competitive edge in any industry requires that products are consistently produced. In the snack food industry, this requires that the texture, color, shape and general appearance remain uniform. Image processing methods are attractive for achieving this in a rapid and non-destructive way. In this application note we describe how a major snack food producer has saved money by avoiding off-spec production.
The desired outcome for this project was to quantify the seasoning level on different snack food products. We were able to solve several problems:
- removing interference from the background conveyor belt and shadows caused by overlapping snacks,
- predicting the seasoning level from a pre-processed digital image,
- achieving rapid processing times per image.
The background removal step
A rapid and robust technique was developed to remove the background from the image. The method was so effective that it managed to pick out not only the background, but also other unusual objects.
Left: the raw image as captured on-line and right: the preprocessed image: all non-snackfood objects (hand is due to grab-sampling) and background pixels are automatically discarded.
Seasoning prediction
This critical step was achieved by extracting feature vectors from the image. Prediction of the laboratory data was accurate. It was then decided to apply the technology on-line, which led to the discovery of seasoning variation that had not been seen before.
Assessing the predictions: the on-line predictions were compared to laboratory measurements during an intentional change in process setpoint.
Benefits: Moving to feedback control
The success at this point led the manufacturer to make process changes to implement feedback control. The closed-loop control system has been in place for over three years and has shown a 50% reduction in the seasoning content error. Processing times of less than 1 second per image have been achieved using an at-line machine vision system from Cognex.
Your product's appearance is critical to quality. Let ProSensus work with you to implement a machine vision solution beyond the ordinary.
