Abstract: A document image scanner that converts scanned images for output as bilevel images is provided with a bilevel image filter. The bilevel image filter counts the number of continuous pattern elements in each direction, vertical, horizontal and diagonal, from a specific point and compares the results with a predetermined reference. Patterns falling below the reference value are regarded as resulting from background noise and are erased.

Abstract: An image scanner that can extract the information of interest from a document at high speed, using a relatively small-scale circuit arrangement that provides an image processing performance equal to that obtained by applying convolution to a larger number of pixels. Light reflecting from the document is converted to electrical image signals by a one-dimensional image sensor. After these image signals have been digitized by an A/D converter, they are input to an adder. A portion of the digitized signals is input to a rounding circuit in which the average intensity of a pixel unit, each comprised of a prescribed number of pixel groups, is calculated. These units are treated as pseudo pixels on which convolution is performed by a convolution integrator. A subtracter is then used to obtain the difference between signals input from the A/D converter and signals output by the convolution integrator.

Abstract: A document scanner that is able to reliably discriminate and scan the information side of each simplex document of a stack of documents, i.e. The side containing information, even when some of the documents are upside-down.

Abstract: An image scanner is provided that receives light reflected from a same position on a document by first, second, and third one-dimensional image sensors arranged in parallel. The second image sensor is a high-resolution image sensor comprising a plurality of photocells, which is disposed between and in a spaced-apart relationship with the first and third one-dimensional image sensors which are each low-resolution image sensors comprising photocells which are larger in size than the photocells of the second one-dimensional image sensor. Electrical image output signals from the first and third low-resolution image sensors are added, and any high-frequency components in the added signal are removed by a low-pass filter for producing signal data relating to the mean brightness of the region around a pixel of interest.

Abstract: A document reader (scanner) is disclosed which can automatically provide a provisional decision on the acceptability of the document image quality, and display the documents judged to be unacceptable for visual confirmation, using a display means. The apparatus can detect skewing of documents and anomalous document image contrasts, and the degree of skewing to be detected can be adjusted as required.

Abstract: A half-tone binarization generator that produces high-quality half-tone binarization images by converting multilevel brightness information into sets of black and white bitonal data by adding noise to the multilevel brightness information and using a thresholding technique.

Abstract: In a document for sensing information, while the document to be sensed is fed in one direction, both surfaces of the document are illuminated by the respective sources of light. Light reflected by one and then the other surface of the document alternately reach a one-dimensional image pickup element. The light sources may be turned on and off. Alternately, the sources of light may be left on, in which case light reflected by both surfaces of the subject are intermittently interrupted.

Abstract: An image binarization system in which the threshold value used for the binarization process can be adjusted to thereby enable the process to be made more accurate and avoid loss of black areas in characters in the process of digitizing and conversion. The threshold value is based on the average value of pixel density values around the pixels to be binarized, and is corrected downward when the average density value of the surrounding pixels is larger than a specific boundary value, and upward when the average value is smaller than the said boundary value.

Abstract: In inspecting plated through holes in printed circuit boards, light from a light source is introduced into the light conducting substrate of the printed circuit boards having through holes. A light detector senses the light in the holes. The detected through holes are masked to prevent the light from entering the through hole of the substrate. A light detector senses light leaked to the hole. By signals supplied from the light detectors, the plated through holes can be continuously and efficiently inspected.

Abstract: A pattern inspection system for inspecting a pattern formed on a base, such as a photomask, by means of laser beam scanning which includes a device for detecting the body and edges of the pattern, a memory device having a plurality of memory units for separately storing the detected body and plurality of edges of the pattern, a device for measuring the width of the body of the pattern between two parallel edges of the pattern, a device for detecting and correcting missing pattern edges, a device for inverting the pattern, a device for reducing the pattern, and a device for eliminating pinholes and stains within the pattern.

Abstract: A pattern inspection system, for inspecting a pattern formed on a base, such as a photo-mask, by means of laser beam scanning, which includes a device for detecting the body and edges of the pattern a memory device having a plurality of memory units for separately storing the detected body and plurality of edges of the pattern, a device for measuring the width of the body of the pattern between two parallel edges of the pattern, a device for detecting and correcting missing pattern edges, a device for inverting the pattern, a device for reducing the pattern and a device for eliminating pinholes and stains within a pattern.