JPH05236276A - Picture processing system - Google Patents

Abstract

PURPOSE:To obtain a pseudo halftone binarizing picture with high quality compatible with an output printer. CONSTITUTION:Output use density correction tables 2, 3 are provided to be compatible with printers with different output forms in the pseudo halftone binarizing method in which a halftone picture including density of a halftone is binarized. An output density correction table for a relevant printer is selected by a selector 4 and a printer identification discrimination section 5 depending on the printer for output and an original picture is corrected based on the density correction table selected. Pseudo halftone binarizing processing is applied to picture data after correction by using a pseudo halftone binarizing circuit 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing system, and more particularly to a binarization processing device for halftone images.

[0002]

2. Description of the Related Art A conventional halftone binarizing apparatus assumes only one type of output device, performs density correction so that the output of the printer has high quality, and then performs halftone binarizing processing. Was there. Pseudo halftone binarized image is output by laser beam printer, thermal printer, or LED.
Any of the various printers, such as the printer, will cause a significant difference in the output image. This is because the blackout condition differs depending on the relationship between the dot shape and the solid black output.
Conventionally, halftone binarization of an image is performed after density correction so that a high quality image can be obtained when the image is output by a laser beam printer, a thermal printer, or another type of printer. .

[0003]

However, for that reason, when the conventional apparatus does not perform the correction corresponding to the printer, the output image may be blackened or too white and the image quality may be deteriorated.

The present invention is intended to solve these problems and has a plurality of correction tables for printers according to the output format of the printer. After the correction tables are switched for correction and correction is performed, the pseudo halftone is used. An object of the present invention is to provide an image processing method capable of performing a binarization process and obtaining a high-quality pseudo intermediate binary image compatible with an output printer.

[0005]

In order to solve the above-mentioned problems, the present invention provides a pseudo halftone binarization method for binarizing a halftone image containing halftone densities to printers having different output formats. It is characterized in that a density correction table for output is provided correspondingly.

[0006]

According to the present invention having the above-mentioned structure, the density correction table is switched according to the printer to be output, the original image is corrected by the density correction table, and the pseudo halftone binarization processing after correction is performed. Then, a high quality pseudo intermediate binary image compatible with the output printer is obtained.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a first embodiment of the present invention. In the figure, 1 is an input unit, 2 is a table A, 3 is a table B, 4 is a selector, 5 is a printer type discrimination unit,
6 is a pseudo halftone binarization circuit, and 7 is an output unit.

The input unit 1 is supplied with digitally converted multi-bit image data from an image reading device such as a sensor in pixel units. The table A2 is an image data correction table for the laser beam printer here.
This conversion table is used to achieve a visually high quality output of the laser beam printer after the pseudo halftone binarization process. The table B3 is an image data correction table for the thermal printer here. The selector 4 selects and outputs the data corrected by the table A2 or the data corrected by the table B3 according to the signal from the printer type determination unit 5.

The printer type discriminating section 5 determines whether the output section 7 is a laser beam printer or a thermal printer, and the table A2 is used.
A signal for selecting the table B3 is output. The pseudo-halftone binarization circuit 6 is a pseudo-halftone binarization circuit such as systematic dither or error diffusion method.
Quantize and output.

The output unit 7 is finally a laser beam or thermal printer. However, when the device equipped with this image processing apparatus is a facsimile machine, the output section is an encoder and a facsimile on the receiving side, and is a laser beam or a thermal printer.

FIG. 2 is a diagram showing the difference in characteristics between the laser beam printer and the thermal printer. The shaded area in the figure indicates the printed area. As can be seen from the figure, the laser beam printer has circular dots as shown in FIG. 2 (a), and the thermal printer has a square shape as shown in FIG. 2 (b). Due to this difference in shape, the output is different even for the same image, and in particular, blackout appears as in the laser printer of FIG. 2 (a). FIG. 3 is a diagram schematically showing the difference in these output characteristics for each concentration.

The tables A2 and B3 are determined based on the output characteristics shown in FIG. FIG. 4 is a characteristic diagram of the correction data stored in these tables.

In this way, the table for correcting the original image is determined in consideration of the output characteristics of the printer, and the table is selected in accordance with the printer, corrected, and binarized to obtain the gradation. A good and high quality pseudo gradation binary image can be obtained.

[0014]

As described above, according to the present invention,
A plurality of image correction tables are provided, and these correction tables are selected in correspondence with each printer to perform correction, and then pseudo halftone binarization processing is performed and output, whereby a high-quality halftone image is obtained. As described above, the present invention is excellent as preprocessing for pseudo-halftone binarization processing, and is particularly effective for a device such as a facsimile machine having a different destination printer format.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing print dots of a laser beam printer and a thermal printer.

FIG. 3 is a characteristic diagram showing output characteristics of a laser beam printer and a thermal printer.

FIG. 4 is a characteristic diagram showing characteristics of correction data in a laser beam printer and a thermal printer.

[Explanation of symbols]

 1 Input Unit 2 Table A 3 Table B 4 Selector 5 Printer Type Discrimination Unit 6 Pseudo Halftone Binarization Circuit 7 Output Unit

Claims (1)

[Claims] 1. A pseudo halftone binarization method for binarizing a halftone image containing halftone densities, wherein a density correction table for output is provided for printers of different output formats, According to the image processing, a density correction table for output of the printer is selected, the original image is corrected by the density correction table, and the pseudo halftone binarization process is performed on the corrected image data. method.