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Image Analysis and High Dimensional Control Chart for Inspection of Sausage Color Homogeneity and Uniformity

Kaewsuwan, Piraya, Yuangyai, Chumpol, Cheng, Chen-Yang, Janjarassuk, Udom
International journal of food engineering 2016 v.12 no.7 pp. 625-635
color, colorimetry, image analysis, sausages
Sausage color usually influences consumers’ selection due to the perceptions of quality. Extensive studies have applied image processing to capture the characteristics of food products according to the high-dimensional nature of the resultant images. However, the color homogeneity (i. e. “within pack” variation) and uniformity (i. e. “between-pack” variation) have rarely been studied. Therefore, this paper proposes a new framework to detect both variations using images. In addition, a new approach has been developed to deal with high-dimension data involving colorimetric characteristics, namely L*, a*, b*, hue (h) and chroma (C*). These high-dimensional data are transformed to represent color homogeneity and uniformity. Hotelling T² chart is used to detect color abnormalities. Our approach indicates that the out-of-control items can be identified with the control chart signals. Nonetheless, the out-of-control signals alone are inadequate for determination of the possible causes. Then, the proposed analysis framework was subsequently applied to identify possible causes that contributed to the process deviations. Furthermore, prior to the experiments with sausages, the image inspection device was tested for gauge repeatability and reproducibility.