Dainippon Screen Mfg. Co., Ltd.

Yoshihiro Kishida

Shigeru Sasada

Makoto Hirosawa

Yukihiko Inagaki

Shinichi Nagata

Yoshiharu Itano

A small-sized flatbed scanning type image reading apparatus for reading a wide-range image at high resolution is provided. An optical reading system (LU) is movable also in a main scanning direction (X) for high-resolution wide-range image reading. The optical reading system (LU) scans the image with the width of a section (SS,) to be read of elongated rectangular configuration in a subscanning direction (Y), and then is shifted in the main scanning direction to scan the image with the width of the next section (SS,) to be read. The remaining section (SS,) to be read is similarly scanned. The images of these three sections are combined together in consideration for the influences of overlap parts (OL,, OL,) of the sections.

Method of and apparatus for reading image by flatbed scanning

A plurality of reference tone curves are determined in advance. An operator divides an original image into image regions and selects respective reference tone curves (f.sub.1 (x), f.sub.2 (x)) for the image regions. The operator designates weight values for the respective reference tone curves. A weighted average of the respective reference tone values is calculated with the weight values to obtain a tone curve which is then employed to convert the gradation of the original image.

Method and apparatus for producing a corrected image from an original

The present invention provides an image processing apparatus. The image processing apparatus is capable of determining a color-separation condition suitable for any kind of prepress scanner and comprises an image reading unit. A converting condition storing device stores data relating to at least one converting condition for converting first R.G.B. signals obtained through reading by the image reading unit into second R.G.B. signals which are substantially equivalent to signals which would be obtained through reading by a different image reading unit within one kind of prepress scanner. A first converting device changes the first R.G.B. signals into second R.G.B. signals in accordance with the converting condition data. A second converting device changes the second R.G.B. signals into C.M.Y. or C.M.Y.K. signals in accordance with color-separation condition data. A color-separation condition correcting device corrects the color-separation condition, and a visual image display produces a visual image from the C.M.Y. or C.M.Y.K. signals obtained by the second converting device during each color-separation condition correcting step until a final correction is achieved.

Apparatus and method for converting and displaying R, G, and B signals

A light beam scanning system for scanning an object with a light beam emitted from a light source to record or read images includes a lattice plate disposed in a position equivalent to a scanning plane of the light beam and extending in a primary scanning direction. The lattice plate includes a plurality of light transmitting sections each having a width substantially corresponding to a diameter of the light beam in an in-focus position. Photodiodes or the like are provided to detect quantity of the light beam having passed through the light transmitting sections of the lattice plate. Since the detected quantity of the light beam is correlated with focus displacement of the light beam, amounts of focus displacement of the light beam at different points in the primary scanning direction are determined from the detected quantity of the light beam. When recording an image, the quantity of the light beam is adjusted based on the determined amounts of focus displacement to equalize print line widths at different points in the primary scanning direction.

Light beam scanning system

A photosensor (20a) has a pair of n-type semiconductor layers (21U, 21D) formed on the major surface of a p-type semiconductor substrate (31). A light-shielding pattern (24) comprised of unit light-shielding layers (33) is formed on the major surface of the substrate. When the major surface is scanned by a light beam in the direction (D.sub.X) in which the unit light-shielding layers are aligned, a couple of photo-conversion signals indicating a current position of the light beam on the photosensor are generated in the photosensor. Since the light-shielding pattern is directly provided on the sensor body, no grating glass is required other than the photosensor.

Photosensor and image scanner utilizing the same

An image reader includes a half mirror or the like disposed in an optical path extending from an input optical system to a CCD line sensor, and a linear light source disposed in an optical path branched out by the half mirror. The linear light source is located at a position equivalent to the CCD line sensor with respect to a document table, and is equal in length to an effective pixel region of the CCD line sensor. Light emitted from the light source is projected back to the document table. An effective image reading area is displayed on the document table by relatively moving the document table and linear projected image in a sub-scanning direction. The linear light source is rotatable in accordance with a desired setting angle of an original. Consequently, an inclined image is projected back to the document table to serve as a guideline for setting the angle of the original. Where a spot light source is substituted for the linear light source, a spot image projected back to the document table is moved along a trimming area of an original. The trimming area is automatically determined by detecting distances of movement of the spot image.

Flat bed scanning type image reader

An image scanner for producing a halftone image is provided with a halftone signal generator which generates an exposure signal (S) for controlling the exposure duration of a laser beam (L) which beam is focused on a photosensitive material. The halftone signal generator is so constructed that image data (N) is compared with a threshold data (screen pattern data) for each elementary area and the exposure duration for each elementary area is determined mainly according to a difference between the image data and the threshold data. Some of the elementary areas are partially exposed, to an extent which depends on the exposure duration.

Method of and apparatus for recording halftone image

A light beam deflection scanning method including the steps of: (a) finding data for cancelling distortion of a scanning track to be made on a surface of an object by a light beam focussed on the surface by a scanning lens, the distortion being caused by the lens; (b) directing the light beam at the surface through a scanning lens and deflecting the light beam in a main scanning direction; (c) detecting the position of the light beam on the surface; and the deflecting in step (b), deflecting the light beam in a subscanning direction by an amount based on the data, to thereby cancel the distortion of the scanning track.

Light beam deflection scanning method and an apparatus therefor

An optical system, useful for a flying-spot scanning apparatus includes a laser tube, an acousto-optical modulator, a deflecting mirror directing the laser beam in a first direction, and an objective lens having the characteristic of h=f.multidot.sin .theta., where h is the distance on an object between the optical axis and the point upon which the laser beam impinges, f is the focal length of the objective lens and .theta. is the angle formed by the beam entering the objective lens with respect to the optical axis. The objective lens includes a first optical unit having the negative focal length and a second optical unit having a positive focal length. The third-order distortion coefficient of the objective lens is approximately '1'. Straight and parallel scanning loci can be effected on a recording medium, as the recording medium is fed in a second direction.

Optical system for flying-spot scanning system

By using the initial control voltage or the subsequent control voltage corresponding to the type of the aperture to be set in an input scanning head, the maximum output current of a photomultiplier of an image reproducing system is regulated.

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Kyoto, Japan

Yoshihiro Kishida