A surface inspecting apparatus comprises an image achieving unit for achieving an image of a surface of an object; and a controller for providing the symmetry feature of the spot or contaminant by using the magnitude of the intensity gradient and the orientation of the intensity gradient for each pixel of the achieved surface image to thereby detect a spot or contaminant on the surface. The controller detects the spot or contaminant by using a symmetry magnitude map formed by the magnitude of the intensity gradient and the orientation of the intensity gradient of each pixel, after achieving the magnitude of the intensity gradient and the orientation of the intensity gradient by using a gradient operator on the achieved surface image, wherein the symmetry magnitude map provides the internal symmetry feature of the spot or contaminant.
A plurality of images that include the same eye is input (S11) and iris regions are extracted therefrom to obtain iris images (S12). After the plural iris images are subjected to transformation from a rectangular coordinate system to a polar coordinate system (S13) and rotational compensation (S14), the images are added together while a weight is attached to a pixel value in each coordinate of the polar coordinate system, to accumulate them as a single iris image (S15). An iris code is generated from the thus obtained single iris image (S16, S17).
An image-based technique that measures the orientation of fibers in a moving web of nonwoven material. At least four light spots on one side of the web are illuminated essentially simultaneously with at least four plane-polarized incident substantially perpendicular light beams having different polarization characteristics. Dispersion of the excident light spots is measured on the opposite side of the web along at least one linear section which is at a known angle relative to the plane of polarization of the corresponding plane-polarized incident light beam, wherein at least one such linear section lies substantially across the center of the transmitted excident light spot and extends substantially across the width of the transmitted excident light spot. Variations in the dispersion of the transmitted excident light spot for the at least four plane-polarized light beams are calculated, and the fiber orientation is estimated from the variations.
An image-based measurement technique that directly measures the crepe pattern on a moving sheet employs a suitable arrangement of illumination, optical elements, and an imaging device to obtain digital images of the sheet surface. The image resolution is sufficient to represent tissue crepe folds at the scale of the crepe. A spectral analysis of some or of all the images reveals the crepe folding pitch. Further analysis of the image optionally reveals other crepe structural parameters, such as the distribution of crepe fold orientation angles and distribution of linear fold lengths. Corrective actions can be implemented in response to changes in the crepe structure. The pitch of creping is the primary parameter for describing the crepe pattern; in addition, analyzing the images with a gradient operator can yield information regarding the orientation of the crepe folds and distribution of angles of the crepe furrows on the hood side or equivalently of the crepe seams on the cylinder side.
