Abstract: In a method of joining image data divided into a plurality of parts each having an overlap region with the other at a border line portion into a single image for output, an image processing apparatus joins the plurality of partial images having overlap regions L at border line portions. The image processing apparatus extracts a joining line connecting pixels with small density difference between partial images from the overlap region, and joins the partial images with each other along the joining line. The image processing apparatus extracts a line connecting pixels with small density difference with adjacent pixels from the overlap region of the partial images as a joining line upon extracting the joining line. The density difference at the joining border is minimized in order to make the joining line look more natural, and make offset of images in the overlap region less recognizable.

Abstract: An image reader for reading book-like documents placed on a document platen in a face upward condition, said image reader comprises a shading reference panel provided beside the document platen which is white in color and of uniform density, an image reading device which reads the document platen on which the book-like document is placed and the shading reference panel, and outputs image data, a height detector which detects a height distribution of the book-like document, an illuminance detector which detects an illuminance irregularity in accordance with the image data corresponding to the shading reference panel, calculator which calculates shading correction data in accordance with the height distribution and the illuminance irregularity on the shading reference panel and, shading corrector which corrects the illuminance irregularity of the image data corresponding to the book-like document in accordance with the shading correction data.

Abstract: The present invention provides an apparatus which separately reads and combines a plurality of partial images of a large document so as to produce simply and accurately produce a composite image of excellent precision at the joint boundary of each partial image without complex positioning operation.

Abstract: An image reader capable of outputting excellent quality read images, without illumination irregularities, similar to that of flat documents even when the document surface is curved as in the case of book-like documents. An image reader provided with a memory to store correction data to correct differences of illumination of each pixel of a document image, and which corrects the read information of each pixel in a document image using correction data corresponding to the measured height of a document surface among correction data stored in the memory. For one aspect, this image reader is constructed so as to correct a group of read information corresponding to a set of pixels arrayed in one direction by excluding specific frequencies among the illumination distribution from the set.

Abstract: An image reading apparatus which reads document surfaces of open book-like documents placed on a document platen in a face upward condition, the image reading apparatus comprises; a first detector which detects a height distribution of a document surface in a main scanning direction, a second detector which detects a height distribution of the document surface in a sub-scanning direction, and a direction discrimination device for discriminating whether a placement direction of the document is a main scanning direction or a sub-scanning direction based on the height distributions.

Abstract: An image reading apparatus for reading documents disposed face upward on a document platen by optical scanning. The image reading apparatus comprises a color correction filter which has characteristics for shielding light of visible light range and is inserted into said imaging system on prescanning to detect the height of the document.

Abstract: A process for preparing a large ZnSe single crystal, comprising vacuum sealing polycrystalline ZnSe prepared by a chemical vapor deposition in a capable and hot isostatically pressing polycrystalline ZnSe in the capsule, by which the ZnSe single crystal having such high qualities as to be used as a substrate on which an epitaxial layer of ZnSe can be grown.