Abstract: An image forming method using an image forming apparatus including: a latent image carrier whose surface is driven in a sub scanning direction; a deflector which scans a beam spot reciprocally in a main scanning direction substantially perpendicular to the sub scanning direction on the surface of the latent image carrier in the use of an oscillating deflect mirror so as to form spot latent images each of which formed on a pixel; developer which develops each of the spot latent images as a pixel-dot, the method includes of: halftoning for a tone reproduction in which a halftone-dot constituted by the pixel-dot(s) is formed on a cell consisting plural pixels according to a fattening type threshold matrix, wherein a plurality of cells are contiguously arranged in the main scanning direction so as to form a plurality of contiguous locations at each of which the cells adjoin mutually in the main scanning direction, each cell includes a larger-than-four even number of pixels in the sub scanning direction, and the c

Abstract: An image formation apparatus using an elecrophotographic process for obtaining a high quality image with tone value R2 of equal to or more than 0.98 is provided. The resolution for light-writing is equal to or more than 1200 dpi and/or light-writing is performed based on image data formed by applying halftone processing at a line frequency of equal to or more than 200 lpi. Light-writing means is accomplished with a laser light beam with a beam diameter equal to or less than 35 ?m. The photoconductor includes a charge generating layer containing a charge generating material and a charge transfer layer containing a charge transfer material laminated on a conductive support. The ionization potential of the charge generating material Ip(CG) and ionization potential of the charge transfer material Ip(CT) satisfy the relationship of Ip(CG)?Ip(CT).

Abstract: A method for printing a halftone digital image on both a printing press and a color proofer using the same binary digital data which comprises making a printing plate from the binary digital data; making a press sheet using a press with the printing plate; sending the binary digital data to a dot-gain processor for conditioning the binary digital data to introduce a predetermined level of dot-gain; transmitting the conditioned binary digital data to the color proofer; and printing a halftone color proof on the color proofer.

Abstract: An image forming apparatus, having a submodule that causes non-uniformity in density in a slow-scanning direction in accordance with rotation, includes a correction image forming unit that forms an image for density correction, in cooperation with the submodule, a density detector that detects a density of the image for density correction, a correction data generation unit that generates correction data to correct a density distribution based on a density distribution of the image for density correction in a slow-scanning direction detected by the density detector, a phase detector that detects a phase of the submodule, and a mark image forming unit that forms a mark image in synchronization with the phase of the submodule detected by the phase detector, in the image for density correction formed by the correction image forming unit.

Abstract: In an embodiment, a region of a photoconductor is exposed to light having an intensity below a threshold sufficient to produce a marking-material-free region or a marking material containing region.

Abstract: An image processing apparatus which converts multiple-value image data of an image into a plurality of dot patterns to form the image on a recording medium includes: a corrected recording element signal table storage device which stores a plurality of corrected recording element signal tables respectively for the graduated tone numbers, each of the corrected recording element signals being one of corrected recording element signal numbers and determined so that banding caused by recording characteristics of the recording elements is corrected in accordance with a correlation between each of the recording elements and surrounding recording elements of said each of the recording elements; a one-dimensional dot pattern table storage device which stores a one-dimensional dot pattern table which specifies a one-dimensional dot pattern for each of the corrected recording element signal numbers; a corrected recording element signal conversion device which converts the multiple-value image data into a one-dimensional

Abstract: What is disclosed is a method for compensating for printer characteristics having a tone reproduction curve which is either too rough to be fitted by interpolation or which does not have a simple parametric function. The method comprising first placing a first set of control points on the tone reproduction curve such that each point is representative of the behavior of the curve in the vicinity of that point and fitting a first smoothed curve to the first set of control points. A subset of points belonging to the set of first control points along the first smoothed curve is moved, thereby indicating a desired change in that region of the curve of the original function. A second set of control points is generated from the set of moved first control points and the remaining unmoved first control points and a second smoothed curve is then fitted to the second set of control points. A differential function between the first and second fitted curves is then determined.

Abstract: An image processing device for processing an input image so as to reproduce a halftone, includes: a matrix setting section for setting a threshold matrix having a plurality of elements arranged in M columns×N rows, at least two threshold values being stored in each of the elements; an element specifying section for specifying a corresponding element of the threshold matrix in accordance with a position of a pixel in the input image; and a multilevel signal generating section for fetching the threshold values from the specified element and for generating a multilevel signal by transforming an input pixel value to one of multiple levels in accordance with the fetched threshold values; wherein the multilevel signal generating section outputs a constant value Doutmin as the multilevel signal when a first condition that the input pixel value is smaller than or not larger than a minimum value of the threshold values, is satisfied; the multilevel signal generating section outputs a constant value Doutmax when a seco

Abstract: In a computer generation of a dither mask for conversion of a continuous-tone image into a halftone image, a pixel array having a size in accordance with the dither mask is partitioned into blocks. Initial pixel values are determined such that the occurrences of pixel values will be substantially uniform in the blocks. A pair of exchange target pixels are selected at random from the pixels in one of the blocks and function values of a predetermined evaluation function that indicates a characteristic of the pixel value configuration of the pixels in this block are computed for the two cases where pixel values are exchanged among the exchange target pixels and where not exchanged. These function values are compared to judge whether exchange should be performed.

Abstract: A halftone processing method for correcting the variation in light intensity on a photoconductive drum and an apparatus using the same, wherein the method includes the steps of preparing a plurality of dithering functions, detecting the position where image data for forming an electrostatic latent image is scanned on the photoconductive drum, selecting one of the plurality of dithering functions according to the detected scanning position, and halftone-processing the image data using the selected dithering function. Accordingly, the halftone processing method improves print quality by increasing light intensity at the edges of a photoconductive drum by permitting the laser printer to be halftone-processed using dithering functions whose critical values are different for the center and the edges of the photoconductive drum.

Abstract: There is provided an image forming apparatus which is capable of quickly performing measurements required for obtaining a proper image density. The image forming apparatus having a plurality of image forming apparatuses performs an image density adjustment control process by carrying out a maximum density control process at a reference image forming speed, and carrying out a density gradation control process at each of the plurality of image forming speeds. Image forming conditions for carrying out the density gradation control process at speeds other than the reference image forming speed are determined by performing operation on image forming conditions determined by the maximum density control process carried out at the reference image forming speed.

Abstract: A plurality of color signals indicative of a plurality of color patterns are processed based on a first distribution curve to distribute the original color signals into color signals for normal ink and color signals for light ink. Then, the plurality of color patterns are printed by the color signals for normal ink and color signals for light ink. Then, the density of each color pattern is detected to produce a density curve. A second distribution curve is produced based on the detected density, the original color signals, and the first distribution curve so that the second distribution curve can attain a properly linearly-changing density curve. By preparing beforehand a plurality of first distribution curves dependently on a variety of usage conditions of the printer, it is possible to use a second distribution curve that is in conformity to the usage condition, under which the printer is desired to be driven, by selecting a distribution curve that corresponds to the usage condition.

Abstract: A printing apparatus is provided with multiple achromatic color inks having different densities and at least one chromatic color ink. Diversity of dots are created with the multiple achromatic color inks on a printing medium according to image data to form a black and white image where dots are inconspicuous. Dots of the at least one chromatic color ink are created according to lightness of an image to be mixed with the dots of at least one of the multiple achromatic color inks. This technique gives a high-quality monochromatic image with hue, where dots are inconspicuous. In the case of the printing apparatus provided with multiple chromatic color inks, a ratio of densities of these multiple chromatic color inks to one another is set to express a high-quality monochromatic image with desired hues. The printing apparatus provided with three different color inks, cyan, magenta yellow, as the multiple chromatic color inks, enables color images to be printed.

Abstract: A photosensitive body has a photosensitive layer. An optical scanning device has a deflector deflecting a light flux emitted from a light source, and scans the surface of the photosensitive body by the thus-deflected light flux. A dot is formed at a center between adjacent light fluxes as a result of the adjacent light fluxes being overlapped with one another in a sub-scan direction. A ratio of a static beam-spot diameter Ws in the sub-scan direction on the surface of the photosensitive body defined by 1/e2 of the maximum value in the exposure distribution of the beam spot to an interval L between adjacent scan lines satisfies the following formula: 1.2<Ws/L<4.5.

Abstract: A method and arrangement for producing charge images of images to be printed in an electro-photographic printer or copier device. The method and arrangement provides for printing of different gray scale levels on the print medium by controlling LEDs that are directed toward a photo-conducting intermediate image carrier to emit a different number of successive light pulses. The number of pulses depends on the gray scale level of the raster image portion. The light pulses overlap on the intermediate image carrier to effect correspondingly different charge levels. The intermediate carrier is developed by the application of toner and the toner is transferred to the print medium.

Abstract: The present invention provides a compact printer that can print images of high quality even if the images are printed successively. A temperature at the time of turn-on is detected by a temperature sensor, and a CPU estimates the temperature of an exposure head at the start of exposure based on the detected temperature. The CPU creates print data by referring to a look-up table in accordance with the estimated temperature and drives the exposure head in accordance with the print data, thereby forming a latent image on an instant film sheet.

Abstract: Temperature is detected by a temperature sensor disposed near a recording head. When the detection result is a temperature that is higher than room temperature, an appropriate movement amount of the recording head is calculated from a relation between response speed of the temperature sensor and a LED light amount, and a moving speed of the recording head is controlled. When the result of the detection by the temperature sensor is a temperature that is lower than room temperature, an appropriate exposure amount is calculated from the relation between the response speed of the temperature sensor and the LED light amount, and the amount of light emitted by LEDs is controlled.

Abstract: An image processing apparatus, which performs color conversion for input tone data in an RGB color space to obtain tone data for a CMY color space, and which performs halftone processing to convert the tone data in the CMY color space to image reproduction data, is characterized in that a gamma characteristic A for an output density for a tone in the RGB color space is identical to a gamma characteristic B for an output density for a tone in the CMY color space in the halftone processing. In accordance with the invention, for the color conversion, even when the tone data for the RGB color space between the grid points of a color conversion table is obtained by interpolating the tone data for the CMY color space, the halftone process is performed for the RGB tone data in accordance with the same gamma characteristic B. Thus, image reproduction data can be obtained that provide the same output density as the output density allocated for the tone data of the RGB color space.

Abstract: An electrostatographic recording method for printing an image on a receiver comprising the steps of: operating a primary charger to establish a uniform primary voltage level on an image recording member; developing a control patch on the image recording member, measuring density of the control patch to thereby provide a density measurement signal; converting the image into a digital bitmap comprised of an array of pixels wherein each pixel is assigned a digital value representing marking information; rendering the digital bitmap by defining each pixel as either a background pixel, interior pixel, or an edge pixel and reassigning the digital value of one or more of edge pixels or interior pixels independently and as a function of the density measurement signal; modulating electrostatic charge on the image recording member as a function of the digital bitmap after rendering.

Abstract: An image forming apparatus is provided that is capable of forming an image with excellent gradation quality without affected by variations in the sensitivity characteristic of the photoreceptor and the light quantity characteristic of the LED print head among individual products. A highest gradation appropriate exposure amount appropriate for the highest gradation is calculated from the sensitivity characteristic of the photoreceptor and the light quantity characteristic of the LED print head. Then, based on the highest gradation appropriate exposure amount, an appropriate lighting time of the LEDs that is appropriate for each gradation is calculated so that the increment of the exposure amount between the gradations including the first gradation, and the lighting times of the gradations are set based on the appropriate lighting times. Then, the LEDs are lit for the lighting time set in accordance with the gradation of the inputted image data.

Abstract: The image forming apparatus includes, a movable first image bearing member on which a toner image is formed; and a movable second image bearing member which is brought into contact with the first image bearing member and to which the toner image on the first image bearing member is transferred, in which the toner image on the second image bearing member is transferred onto a transferring material, a dot-shaped dot image formed of a toner different from the toner image is formable on the first image bearing member, and the dot image is variable according to a condition upon forming the toner image on the transferring material. Thus, there is provided an image forming apparatus capable of forming a final image with a high quality in a stable manner independently of a selection of a type of transferring materials or image quality mode as well as suppressing an image streak occurrence.

Abstract: The image forming apparatus includes a movable first image bearing member on which a toner image is formed, and a movable second image bearing member which is brought into contact with the first image bearing member and to which the toner image on the first image bearing member is transferred, in which a dot-shaped dot image formed of a toner different from the toner image is formable on the first image bearing member, and in which a distance between dot centers of the dot images is equal to or smaller than a width of a contact part between the first image bearing member and the second image bearing member in a moving direction of the first image bearing member. Consequently, it is possible to steadily suppress an image streak occurrence and to obtain a final image having a high quality in a stable manner.

Abstract: In a gradation display method, an image is divided into pixels having fine areas, this pixel is furthermore divided into very fine pixels (Si) having very fine areas, and then gradation is displayed based upon a ratio of a colored very fine pixel (Si) with respect to all of very fine pixels (Si) within a pixel. Also, the above-described colored very fine pixel (Si) is formed by both a first growth core which is formed by increasing the number of colored very fine pixels of a single cluster, and a second growth core which is formed by increasing the number of colored very fine pixels of another single cluster.

Abstract: An image forming apparatus using a multi-scan system is capable of forming an image at a high speed. An exposure device scans a surface of the photo conductor by light beams emitted by a plurality of light-emitting elements so as to simultaneously form a plurality of electrostatic latent images at a plurality of positions on the photo conductor, a pitch of the light beams in a sub scanning direction being smaller than a beam diameter defined by a value of an intensity of the light beam at which an intensity level of each light beam is 1/e2 of an intensity level at a center thereof, the electrostatic latent image being formed also at a position where the plurality of light beams overlaps with each other. A code of a plurality of levels is produced from image data in accordance with a pattern detection matrix. A pulse with output from the pattern detection processing means is produced with reference to pulse width data which designates a pulse width of each light beam previously set in response to the code.

Abstract: An image forming apparatus and toner-consumption-estimation method that can accurately estimate the amount of consumed toner regardless of the type of image. A printing-pixel-counting unit counts from input image data the number of printing pixels. Also, an edge-counting unit similarly counts from the input image data the number of edges being boundaries between the printing pixels and blank pixels. A consumption-estimation unit then calculates the amount of consumed toner based on the counted number of printing pixels and the number of edges.

Abstract: The image forming method carries out reverse development with a developer that has a toner prepared by agglomerating resin particles in a water based medium.

Abstract: An image processing apparatus for a laser printer, wherein a halftone control through laser pulse modulation (PWM) is used in combination with distributed clustered-dot halftone processing which distributes a tone level over four clustered-dots, and the value represented by higher bits of a threshold are used to switch a PWM pulse pattern in a highlight area to a discontinuous pattern, thereby implementing the high density halftone processing, which provides a high highlight tone density and stability, only with a small scale memory and circuit.

Abstract: A system and method for minimizing distortion in printed images due to toner explosion receives the incoming image bit stream and monitors the stream for horizontal lines and edges that would be particularly susceptible to toner explosion distortion. When such features are determined, the bit stream is modified to print an outlined area with a fill pattern therein. This decreases the amount of toner used to print the horizontal line or edge. As less toner is required, toner piles transferred to the paper are shorter and, therefore, tend to generate less distortion when toner explosions occur.

Abstract: An apparatus for printing a color image includes a printer driver which processes input image data to generate printable image data, and further includes one or more color profiles which are used by the printer driver to perform color matching on the input image data in a normal mode, wherein the printer driver uses one or more toner-saving-purpose profiles to perform color matching on the input image data in a toner saving mode, the one or more toner-saving-purpose profiles being specifically designed to reduce a toner amount on a printed color image.

Abstract: The present invention generally provides methods and systems for printing. A statistical learning system is used to determine dot gain.

Abstract: An image reproduction engine which causes toner to adhere to a development region of certain area located at a certain position within dots according to image reproduction data is utilized for image processing, wherein a halftone is expressed by means of halftone spots formed from a plurality of dots. The centroid of the halftone spot formed from a single dot or a plurality of adjacent dots is shifted from the center of the dot to an arbitrary position, thus achieving desired screen angles or desired pitches of halftone spots. As a result, screen angles related to an irrational tangent can be realized, and the pitches of halftone spots of a plurality of color screens can also be made uniform. 31.

Abstract: A laser modulating and driving device comprises a modulation signal generating unit configured to generate a laser modulation signal consisting of a pair of small swing differential signals based on pixel data, and a driving unit configured to drive a laser according to the laser modulation signal supplied from the modulation signal generating unit.

Abstract: An optical signal control process and circuit providing an improved electronic photography method reproduction apparatus. The reproduction apparatus has a data transmitting unit converting data to be printed to a series of video data in accordance with a first clock signal and transmitting the converted video data in response to a horizontal synchronization signal applied with a predetermined time interval, and a printing control unit for controlling a mechanism used to print the video data by sending electrical signals, providing beam data used to switch the light generation of a light source element controlled by chopped chopping video data applied to the light source element, and generating the horizontal synchronization signal on the basis of a beam detection signal produced by the light source element.

Abstract: An image forming apparatus adds a plurality of dots of image date in the subscanning direction and starts generating a density from a particular pixel, and switches PWM (Pulse Width Modulation) right and left phases in order to concentrate potentials and to increase a saturation region. It is therefore possible to stabilize image density in a highlight portion and therefore realize high quality images, while reducing banding and image noise.

Abstract: There is provided an image forming apparatus that enables the formation of high-quality multi-level images by ensuring that the size of blocks into which the image is to be divided is specified in accordance with the resolution of the image to be recorded. The apparatus divides input image gradation level data into a plurality of blocks and performs graduated recording by converting the divided image gradation level data into multi-level recording data in accordance with gradation conversion characteristics determined as keyed to relative positions in each of the blocks; the blocks are typically set to a size satisfying the following relation: (55/n)<X/p<(65/n), provided p is an integral multiple of 10; where X is the resolution of the image to be recorded in a given direction and expressed in dpi, p is the length of each block in said given direction and expressed in dots, and n is a natural number.

Abstract: Based on the density of an image formed on a photosensitive member or an image recording medium, an amount of correction for uniformalizing the image density in a main scanning direction of a light beam is set. Based on the set amount of correction, the intensity of a light beam in an image region is corrected within a range of one main scan.

Abstract: The invention is a method and apparatus for printing images intended to appear to be of solid uniform color and intensity while conserving the amount of image-generating medium used to form the image. The method and apparatus form such images by continually reducing the amount of an image-generating medium deposited in a first portion of the image from a predetermined amount at an outer edge of the portion to a lesser amount at an inner edge of the first portion.

Abstract: The image forming method uses reverse development to form an image from a toner applied to a latent image on a photoreceptor. The dots that form the latent image have an exposure diameter A (in &mgr;m) while the dots of the toner that form on the latent image have a development diameter B (in &mgr;m). The relationship between the exposure diameter A (in &mgr;m) in the primary scanning direction and the development diameter B (in &mgr;m) in the primary scanning direction of the developed image is: 1.1≦B/A≦1.5. The toner is prepared by fusing at the resin particles in a water based medium.

Abstract: When a halftone image region that is below a predetermined density is to be reproduced, a processing unit controlling an exposure unit selects an exposure pattern that can represent a record dot diameter within a range based on a predetermined rule from exposure patterns prepared in advance. Accordingly, graininess is suppressed. When there are a plurality of exposure patterns that can be applied, the exposure pattern with the lowest number of dots present per 1 inch is employed. Accordingly, a halftone image is formed with the image reproducibility improved.

Abstract: A method and system having real-time control of tone reproduction curves. The machine comprises: a moving photoreceptor; a means for storing a target tone reproduction curve; and, a means for updating a current tone reproduction curve LUT.

Abstract: When a user changes a density adjusting value (developing contrast), and even when variations in the usage state of process characteristics (of the photosensitive body and the developing device) of the cartridge change, the amount of recording agent consumed can be suppressed to be low, and a sharp line image can be recorded. An image forming apparatus of this invention includes an edge detecting portion for detecting an edge of image data, an image data correcting portion for correcting image data inside the edge so as to decrease its density, a laser driving circuit for forming an electrostatic latent image on a photosensitive body, and a correction value determining table for acquiring an instruction value for giving an instruction to correct a density contrast, wherein a correction condition for image data changes in accordance with an instruction value.

Abstract: Imaging offset problems in imaging systems, such as electrophotographic (EPG) printers and copiers, are overcome. Imaging offset results from misaligned exposure units that, when uncompensated, produce dots on a photoreceptor belt at exposure positions that are offset from ideal dot positions. An imaging-offset compensating method of the invention first determines the imaging offset, which is a distance that may include a magnitude and a direction. The imaging offset is determined with respect to the ideal dot position. A time factor is then determined based on the magnitude of the imaging offset for each exposure unit. The time at which each exposure unit is actuated is modified by a respective time factor so that a dot produced by each exposure unit matches the ideal dot location thereof.

Abstract: An image forming apparatus has at least a photoconductor, a charger, and an irradiator for irradiating a light for optically writing in on the photoconductor to form a latent electrostatic image using a process for electrophotography in which a resolution of the optical writing in operation is 1200 dpi or more. Further, the optical writing operation is performed using a laser beam having a diameter of 35 &mgr;m or less. The photoconductor is provided with at least a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance. The charge transporting layer has a carrier mobility of 1×10−5 cm2·V−1·sec−1 or more under an electric field of 3×10−5 V·cm−1.

Abstract: An image forming apparatus using a multi-scan system is capable of forming an image at a high speed. An exposure device scans a surface of the photo conductor by light beams emitted by a plurality of light-emitting elements so as to simultaneously form a plurality of electrostatic latent images at a plurality of positions on the photo conductor, a pitch of the light beams in a sub scanning direction being smaller than a beam diameter defined by a value of an intensity of the light beam at which an intensity level of each light beam is 1/e2 of an intensity level at a center thereof, the electrostatic latent image being formed also at a position where the plurality of light beams overlaps with each other. A code of a plurality of levels is produced from image data in accordance with a pattern detection matrix. A pulse with output from the pattern detection processing means is produced with reference to pulse width data which designates a pulse width of each light beam previously set in response to the code.

Abstract: An image forming and apparatus is provided in which a halftone density of an image is stabilized irrespective of a timing at which writing on scanning lines is started, even when using multiple laser beams. First, it is determined whether or not a portion exposed by adjacent laser beams (i.e., exposed by both of two beams simultaneously) is present. If the result of the determination is affirmative, it is then determined whether or not a portion adjacent to the exposed portion and not exposed by a laser beam is present. If the result of this determination is affirmative, exposure by fine dots is added to the portion not exposed by a laser beam.

Abstract: A printer for printing color toner images on a receiver member of any of a variety of textures. The printer has a number of tandemly arranged electrophotographic image-forming modules respectively including a plurality of imaging subsystems to form a colored toner image transferred to a receiver member, the transfer of toner images from each of the modules forming a color print of the receiver member which is fused to form a desired color print. The image quality of the color print is produced by control of nonoperational co-optimization of fusing parameters and imaging subsystem parameters enabling printing on the variety of textures of receiver member.

Abstract: A dot-matrix image-forming device such as an electrophotographic printer alters the size of a dot according to the surrounding dot pattern, thereby compensating for the tendency of isolated dots or small groups of dots to be undersized due to characteristics of the image formation process. Alternatively, the device may add dots to or delete dots from a contiguous group of dots to achieve substantially the same effect. Preferably, the device both adds or deletes dots and alters the dot size. This compensation scheme enables the total area occupied by dots in a given image region to be proportional to the number of dots in the region, regardless of the dot density and arrangement in the region.

Abstract: When a halftone image region that is below a predetermined density is to be reproduced, a processing unit controlling an exposure unit selects an exposure pattern that can represent a record dot diameter within a range based on a predetermined rule from exposure patterns prepared in advance. Accordingly, graininess is suppressed. When there are a plurality of exposure patterns that can be applied, the exposure pattern with the lowest number of dots present per 1 inch is employed. Accordingly, a halftone image is formed with the image reproducibility improved.

Abstract: An optical scanning device for optically scanning a surface of a photoconductor to form an electrostatic latent image thereupon. The scanning device includes a light source to emit a light flux and pulse modulate the light flux. A deflector deflects the light flux from the light source. A scanning image formation element condenses the light flux deflected by the deflector to form a scanning beam spot on the scanned surface. The scanning beam spot scans the scanned surface to form the electrostatic latent image on the scanned surface. A stationary beam spot, formed by stationary light flux on the scanned surface, has a stationary beam spot diameter &ohgr;m in a main scanning direction that is smaller than a stationary beam spot diameter &ohgr;s in a sub-scanning direction.

Abstract: A multi-tone image processing method and apparatus in which mutually dissimilar tone levels are realized by changing the additive condition of recording energy by means of different recording positions, even when the number of recording operations within a specific range is identical. For example, in an electrophotographic apparatus, when the number of irradiation by a light spot within a specific range remains constant as the irradiation position is changed in the specific range, there is a change in the additive condition of the optical energy within said specific range. Thus, the area rendered visible within the aforesaid specific range also changes, thereby changing the tone level.