In this paper, a study for the prediction of organileptic properties of snack food in real-time using RGB color images is presented. The so-called organileptic properties, which are properties based on texture, taste and sight, are generally measured either by human sensory response or by mechanical devices. Neither of these two methods can be used for on-line feedback control in high-speed production. In this situation, a vision-based soft sensor is very attractive. By taking images of the products, the samples remain untouched and the product properties can be predicted in real time from image data. Four types of organileptic properties are considered in this study: blister level, toast points, taste and peak break force. Wavelet transform are applied on the color images and the averaged absolute value for each filtered image is used as texture feature variable. In order to handle the high correlation among the feature variables, Partial Least Squares (PLS) is used to regress the extracted feature variables against the four response variables.
Information from on-line imaging sensors has great potential for the monitoring and control of quality in spatially distributed systems. The major difficulty lies in the efficient extraction of information from the images, information such as the frequencies of occurrence of specific and often subtle features, and their locations in the product or process space. This paper presents an overview of multivariate image analysis methods based on Principal Component Analysis and Partial Least Squares for decomposing the highly correlated data present in multi-spectral images. The frequencies of occurrence of certain features in the image, regardless of their spatial locations, can be easily monitored in the space of the principal components. The spatial locations of these features can then be obtained by transposing highlighted pixels from the PC score space into the original image space. In this manner it is possible to easily detect and locate even very subtle features from online imaging sensors for the purpose of statistical process control or feedback control of spatial processes. The concepts and potential of the approach are illustrated using a sequence of LANDSAT satellite multispectral images, depicting a pass over a certain region of the earth’s surface. Potential applications in industrial process monitoring using these methods will be discussed from a variety of areas such as pulp and paper sheet products, lumber and polymer films.
Extracting texture/roughness information from grayscale or multispectral images for off-line quality control, or on-line feedback control is a difficult problem. Several statistical, structural & spectral texture analysis approaches for grayscale images (using various pre-defined filters etc.) have been suggested in the literature1, 2 In this paper we propose a new approach based on Multivariate Image Analysis techniques using multi-way Principal Component Analysis. Prior to analysis the grayscale images are transformed into three-dimensional pixel intensity arrays through spatial shifting of the image in several directions followed by stacking the shifted images on top of each other. The resulting three -dimensional image data is a multivariate image where the third (i.e. variable) dimension is the spatial shifting index. Multi-way PCA is then used to extract features (PC scores), which contain the greatest amount of variation. Plots of the observed values of these scores against one another define a score space. Certain regions of this score space contain the texture information of the grayscale image. By masking these regions and tracking the number of pixels having features that fall in these regions, or by comparing the score spaces with template exemplars, one is able to monitor changes in the image surface textural properties. The approach is illustrated using a set of grayscale images of the surface of steel sheet. Based on the textural features extracted from the surface images a simple classification scheme is devised in which each sample image is assigned into one of two classes representing good or bad surface characteristics.
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