Abstract: The invention provides an image formation device based on the electrophotographic system, whereby, when an outputted image varies from the halftone area to the background area in the sub-scanning direction, the density reduction of a rear end area of the halftone area that borders on the background area can be prevented, by means of simplified and small-scale processing. In this image formation device, a backward edge of the halftone area that borders on the background area is extracted, and an image data value of the background area including m pixels after this backward edge in the sub-scanning direction, of input image data Si, is modified to a setting value with correction data. The setting value is set to a value slightly lower than the threshold value corresponding to the dot area coverage of an image recurrence start point.

Abstract: It is made possible to prevent decrease in the density due to the image output characteristic of the image output unit in the subscanning direction by means of a method according to the present invention capable of real-time processing without causing the circuit capacity and the memory to be increased. In an image input unit 100, the input image data is acquired so that its time series direction becomes a direction indicated by an arrow 42 corresponding to the subscanning direction of an image output unit 300. The input image data from the image input unit 100 is corrected in accordance with the image output characteristic of the image output unit 300 in the subscanning direction. The image data after the correction is rotationally processed so that its time series direction becomes a direction indicated by an arrow 41 corresponding to the main scanning direction of the image output unit 300. The image data after the rotary processing is sent to the image output unit 300.

Abstract: An image processing apparatus for converting input color image signals to image recording signals to be sent to an image forming apparatus. The image processing apparatus comprises: a first color converting unit for converting the input color image signals to three-variable color signals independent of devices; a second color converting unit for converting the three-variable color signals to the image recording signals; and a parameter determining unit for determining parameters of the first color converting unit. The parameter determining unit determines the parameters so as to make characteristic colors in the input color image signals coincide with predetermined colors and to maintain linearities of color reproduction characteristics of an output image from the image forming apparatus.

Abstract: The present invention provides an image forming apparatus including first image density signal converter having a first conversion property for converting a multi-valued image density input signal to an image density output signal at a timing synchronizing with an image density signal clock, second image density signal converter having a second conversion property different from the first conversion property for converting a part of the image density input signal corresponding to a low density portion to an image density output signal indicating a value within a range in which an image is not developed, selection signal generator for outputting a selection signal having a period longer than that of the image density signal clock to select the first or second image density signal converter in a predetermined order, a phase of the selection signal being shifted in turn per every one or more main scanning synchronizing signals, pattern signal generator means for generating a pattern signal having a period longer

Abstract: The present invention provides an image forming apparatus having image signal discrimination device for discriminating whether an image density signal belongs to a line image portion or a natural image portion including a halftone image and outputting a discrimination signal, first image density conversion device having a first conversion property for converting the image density signal to a conversion signal and outputting the conversion signal, second image density conversion device having a second conversion property which is different from the first conversion property for converting a range of the image density signal corresponding to a low density portion to a conversion signal indicating a value within a range in which an image is not developed and outputting the conversion signal, selection device for alternately selecting the first and second image density conversion device with a predetermined period, pulse width modulation device for modulating pulse widths of the conversion signals output from the

Abstract: In an image forming apparatus including a pulse-width modulating unit for subjecting an image-density signal to pulse-width modulation and an image-forming unit for forming an image in accordance with a pulse-width modulation signal outputted by the pulse-width modulating unit, an arrangement is provided such that the image is formed with a small number of lines when the image density is a low density, while the image is formed with a large number of lines when the image density is a medium/high density. In an example of the arrangement thereof, the pulse-width modulating unit has a unit for effecting modulation on the basis of a plurality of different modulation periods, and is provided with a selecting unit for selecting a modulation period of a pulse-width modulated wave to be outputted, in accordance with the image-density signal.