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According to the nickel foam surface defect images with the typical characteristics of complex geometry and texture distribution, a nickel foam surface defect detection method based on spatial-frequency multi-scale block local binary pattern is proposed. First, nonsubsampled contourlet is used to carry out foam nickel image multi-scale decomposition, and therefore, low-frequency sub-band images and high-frequency sub-band images are obtained. The multi-scale block local binary pattern is then used to extract the feature histogram vectors of each block region of low- and high-frequency sub-bands, and the histogram feature vectors of the whole image after cascade are formed. The kernel principal component analysis and support vector machine are adopted to reduce the dimension of the feature histogram vectors and used for the defect classification. Experimental results show that the proposed method of feature extraction can extract more detailed texture information, and the average recognition rate reaches to 90%, which meets an enterprise’s needs.

Aiming at the importance of sampling in CCD photoelectric imaging system, the content is studied by us in detail. Firstly, its basic principle is analyzed, and the simple physics explanation and formula deduction are given, and the spectrum expression is obtained. Secondly, the cause of lack sampling is analysed. Finally, the results of experiment verify the correctness of theory analysis.

Aiming at the dark printed circuit board photoelectric image that contains noise acquired by CCD system, the edge detection method by using multi-scale wavelet transform is proposed. Firstly, its basic principle is analyzed in detail, and the simple physics explanation and formula deduction are given. Secondly, the idiographic detection steps are given. Finally, the results of experiment verify the correctness of theory analysis.

Until now, no effective method to measure CCD photoelectric parameters. To solve the problem, a novel measurement method that combines hardware with software is proposed, and it can let hardware and software collaborate with each other to finish assignment together. Firstly, the ideal relation between output voltage and input exposure quantity of CCD is given. Secondly, some main photoelectric parameters of CCD are elaborated. Then based on the principle, test system of CCD photoelectric parameters that combines hardware with software is designed. Lastly, the real relation between output voltage and input exposure quantity of CCD is given, and the test results of experiment of each photoelectric parameter are obtained according to the relation. What’s more, analysis and comparison of the results of the experiment are given in this paper. The method is reliable and the precision is high in the experiment.

In the case of a polychromatic source in X-ray TICT, the variation of attenuation coefficient with energy leads to low energy radiation being absorbed preferentially. In other words, the higher the energy, the lower the attenuation coefficient. With the transmission thickness augmenting, it is easier for X-ray to transmit the matter. The phenomenon is energy spectrum hardening. Thus, hardening correction has to be done. In the present paper, not only is energy spectrum hardening analyzed by theory and the relation stated between attenuation coefficient and transmission thickness in testing composites workpiece, but also the precise accurate theory model for hardening correction of energy spectrum and theory method are reasoned out in testing composites workpiece, which results from Beer's law and the characteristics of X-ray interaction with composites. Then, the attenuation coefficient that has been corrected is used for product back-projection reconstruction. Thus, the effect caused by X-ray beam hardening is wipped out effectively in testing composites workpiece.

In Fourier transform profilometry (FTP), we must restrain spectrum overlapping caused by the nonlinearity of the charge coupled device (CCD) and increase the measurement accuracy of the object shape. Firstly, the causes of producing higher-order spectrum components and inducing spectrum overlapping are analysed theoretically, and a simple physical explanation and analytical deduction are given. Secondly, aiming to suppress spectrum overlapping and improve measurement accuracy, the influence of spatial carrier frequency of projection grating on them is analysed. A method of increasing the spatial carrier frequency of projection grating to restrain or reduce the spectrum overlapping significantly is proposed. We then analyze the mechanism of how the spectrum overlapping is reduced. Finally, the simulation results and experimental measurements verify the correction of the proposed theory and method.

In optical three-dimensional shape measurement, a method of improving the measurement precision for phase reconstruction without phase unwrapping is analyzed in detail. Intensities of any five consecutive pixels that lie in the x-axis direction of the phase domain are given. Partial derivatives of the phase function in the x- and y-axis directions are obtained with a phase-shifting mechanism, the origin of which is analysed. Furthermore, to avoid phase unwrapping in the phase reconstruction, we derive the gradient of the phase function and perform a two-dimensional integral along the x- and y-axis directions. The reconstructed phase can be obtained directly by performing numerical integration, and thus it is of great convenience for phase reconstruction. Finally, the results of numerical simulations and practical experiments verify the correctness of the proposed method.