Abstract: The inventive image recording apparatus records unit images with different combinations of light beams among a plurality of light beams emissive from a recording head when preparing the respective ones of C, M, Y and K plates. Also when the plurality of light beams are dispersed in quantity of light, therefore, density distributions of different tendencies result in the unit images recorded on the respective ones of the C, M, Y and K plates. In a resultant image formed by superposing the unit images with each other, therefore, fluctuation of densities can be canceled and reduced.

Abstract: The present invention provides a light emitting device drive circuit which does not require complicated feedback control for shortening a rising response delay time in the transition from an extinction state of a light emitting device to a light emitting state so as not to increase a bias current, and for eliminating harmful effects due to the influence of a droop phenomenon. A circuit including a series of a coil 55 and a resistor 54 is connected in parallel with an LD 53. In this configuration, the LD 53 is subjected to supply of an overshoot drive current ILD for a time period determined by a time constant of the coil 55 and the resistor 54, i.e., a time period in which a high-frequency current is supplied in the transition from the extinction state to the light emitting state. Thus, a delay in rise time until light emission of the LD 53 can be decreased.

Abstract: The inventive image recording apparatus records unit images with different combinations of light beams among a plurality of light beams emissive from a recording head when preparing the respective ones of C, M, Y and K plates. Also when the plurality of light beams are dispersed in quantity of light, therefore, density distributions of different tendencies result in the unit images recorded on the respective ones of the C, M, Y and K plates. In a resultant image formed by superposing the unit images with each other, therefore, fluctuation of densities can be canceled and reduced.

Abstract: The present invention provides a light emitting device drive circuit which does not require complicated feedback control for shortening a rising response delay time in the transition from an extinction state of a light emitting device to a light emitting state so as not to increase a bias current, and for eliminating harmful effects due to the influence of a droop phenomenon. A circuit including a series of a coil 55 and a resistor 54 is connected in parallel with an LD 53. In this configuration, the LD 53 is subjected to supply of an overshoot drive current ILD for a time period determined by a time constant of the coil 55 and the resistor 54, i.e., a time period in which a high-frequency current is supplied in the transition from the extinction state to the light emitting state. Thus, a delay in rise time until light emission of the LD 53 can be decreased.

Abstract: Experiential gradation correction curves for sample images are prepared. By analyzing the experiential gradation correction curves and accumulated density histograms of the sample images, two points (Y.sub.1, Q.sub.1) and (Y.sub.2, Q.sub.2) are specified, where Y.sub.1 and Y.sub.2 are values of accumulated occurrence and Q.sub.1 and Q.sub.2 are halftone dot percentages for image reproduction. The values Y.sub.1 and Y.sub.2 through an accumulated density histogram of an original image whose gradation is to be corrected. A gradation correction curve Q=G(x) is determined so as to pass through the two points (x.sub.1, Q.sub.1) and (x.sub.2, Q.sub.2).

Abstract: A method and apparatus for detecting the shape of a beam spot on a scanning plane in a scanning optical system having a constant scanning speed. When a relative moving speed of the light beam is not known beforehand, four slits are used to detect intensities of light passing through the slits. Three of these slits have different angles of inclination with respect to a scanning direction, and the remaining slit has the same angle of inclination as one of the three slits. When the moving speed of the light beam is known in advance, the first-mentioned three slits are used. The moving speed of the light beam is derived from a time lapse between signals detected through the two slits having the same angle of inclination. Once the moving speed of the light beam is known, periods of movement required for the light beam to traverse the three slits having different angles of rotation are obtained on the basis of detection signals relating to these slits.

Abstract: In an image recorder, a recording photobeam and a reference photobeam are periodically deflected by a polygon mirror in a main scanning direction. The recording photobeam is supplied to a photosensitive film while the reference beam is supplied to a transparent grating scale on which a transparent area and an opaque area are formed. The combination boundary of the transparent area and the opaque area has a portion parallel to the main scanning direction. The reference beam transmitted through the transparent area is detected, and the photobeams are deflected in a subscanning direction by an acoustic-optical deflector in response to the detected optical amount of the reference photobeam.

Abstract: An apparatus for and a method of stabilizing the quantity of light of a fluorescent lamp employed for illuminating an original to be duplicated or the like. The quantity of light of a fluorescent lamp reflected by a reference plane is detected, when scanning of an original is started, to control tube current of the fluorescent lamp on the basis of a detection signal, to thereby perform feedback control so that a detected light quantity value reaches a constant value. When the detected light quantity value reaches a prescribed value, the feedback control is released and the detected light quantity value is held to control the tube current of the fluorescent lamp on the basis of the held detected light quantity value. Thus, the tube current of the fluorescent lamp is adjusted to be constant on the basis of the held detected light quantity value during a scanning interval for the original to be duplicated, whereby the quantity of light of the fluorescent lamp is stabilized.

Abstract: An image signal is filtered in one or two-dimensions for obtaining an unsharp signal in a detail emphasis process of an image reproduction system.A one-dimensional image signal filtering is carried out in one of the main and sub-scanning directions so that the first K image signals and the other K image signals out of 2K image signals are respectively summed to obtain first and second sum signals, which are subjected to a cumulus computation to obtain a filtered signal U.sub.2 expressed by: ##EQU1## for (2K-1) image signals d.sub.i (i: K, K-1, . . . 1, 0, -1, -k+2 In this regard, a cumulus computation refers to computation expressed by p.sub.n -Q.sub.n +R.sub.n-1 =R.sub.n, wherein P.sub.n is an addition signal and Q is a subtraction signal where n is the input order of each of the signals and R.sub.n-1 is the result of the previous computation.By filtering the thus-obtained (2K-1) one-dimensionally filtered signal U.sub.2i (i=K, . . .

Abstract: A standard gradation correction curve independent of characteristics of an original image is prepared in advance. An accumulated density historgram curve of the original is obtained from image data of the original. A first gradation correction curve is obtained by modifying the standard gradation correction curve, while a second gradation correction curve is obtained by modifying the accumulated density histogram curve. A third gradation correction curve is obtained by linear combination of the first and second gradation conversion curves to perform gradation correction of the image data on the basis of the third gradation correction curve.

Abstract: Image signals inputted from an input device are subjected to A-D conversion through an A-D converter to be stored in memory by at least an adjacent pair of pixels. The pair of pixels are interpolated by interpolation arithmetic circuit so that generated interpolation data and data on the pair of pixels are ordered under control by a timing controller to be outputted.

Abstract: Reference data for correction are obtained by performing main scanning of a reference plane by a photosensor in a defocusing manner through a lens system, to be stored in memories. Image data of the original read by the photosensor through the lens system are corrected through the reference data for correction stored in the memories. Thus, the original can be read in high fidelity.

Abstract: In a method for emphasizing sharpness in picture scanning recording time in a picture reproducing machine a central picture signal obtained by scanning an original picture according to the scanning sequence and peripheral picture signals of the central picture signal which are appropriately weighted are added to the central signal and averaged to obtain vignette signals, and they are appropriately calculated for emphasizing sharpness of the picture signal. In the method as the peripheral picture signals desired numbers of continuous picture signals are selected by centering the central signal in the main scanning and the sub-scanning directions independently.

Abstract: An improved apparatus for measuring the printed area of a printing plate upon which a printing image is formed, of the type having a movable scanning head provided with longitudinally arranged light sources and plural photosensors arranged in parallel with the light sources. The improvement is composed of a proving sensor device separate from and movable independently of the scanning head which includes at least one light source and photosensor. The proving sensor device provides calibration data for correcting the measurements made by the scanning head. It does this by measuring the intensity of reflected light from a totally dark printing area and a non-printing area from anywhere on the printing plate, and a totally reflective surface and totally absorptive surface, which are preferably located apart from the printing plate. The improvement further includes control means for electronically processing the measurement data produced by both the scanning head and proving sensor device.