JPS58137362A - Facsimile equipment - Google Patents

Abstract

PURPOSE:To perform halftone transmission or copying, by providing plural dither pattern matrix and selecting a combination of picture element density and transmission time at an operator's request. CONSTITUTION:An analog picture signal is inputted to slice level setting circuits 3 and 13, binary coding devices 4 and 14, dynamic range deciding devices 6 and 10, and A/D converters 5 and 9 through a variable gain amplifier 2. The outputs of the binary coding devices 4 and 14 are supplied to a mode selecting device 24 and the outputs of the A/D converters 5 and 9 are supplied to the mode selecting device 24 through dither signal converters 16 and 19. The mode selecting device 24 outputs the input signal selectively according to control signals from a console panel 27 and a selected mode controller 25.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a facsimile machine having a function of obtaining pseudo halftones using a dither method, and particularly relates to a facsimile machine having a function of obtaining pseudo halftones using a dither method.
The present invention relates to a facsimile machine having means for selecting one of the pattern matrices in accordance with a mode of image information.

The dither method is a method of pseudo-realizing halftones using black and white binary signals. It is used for copying.

The dither method is widely used as a method for reproducing halftones in facsimile machines because it can reproduce halftones with a relatively simple circuit configuration. However, image information based on the dither method arranges black and white elements according to predetermined rules, giving the human eye a sense of intermediate tones.

Therefore, the run length of image information is generally short, making it poorly compatible with the MH encoding method, which is an international standard binary facsimile signal encoding method, and the MR encoding method.

On the other hand, one of the multiple uses of facsimile devices is to use them as copy machines; for example, devices with a main scanning pixel density of 16 lines/11m1% and a sub-scanning pixel density of 15.4 lines/- have been commercialized. has been done.
Therefore, when the facsimile machine is used in the copy mode, there is no need to reproduce image information via an encoding device or a decoding device, so there is no need to consider the length of the run length.

Furthermore, if it is possible to select a dither pattern matrix according to each transmission speed and pixel density of the facsimile machine, it is expected that the range of use of facsimile machines capable of reproducing halftones will be widened.

However, such a facsimile fMf has not been realized in the prior art. In other words, facsimile machines that can reproduce halftones by using a dither method according to the prior art have only one type of dither matrix pattern. For this reason, it was necessary to decide in advance whether to shorten transmission time at the expense of image quality, or to sacrifice transmission time by sacrificing image quality.

SUMMARY OF THE INVENTION An object of the present invention is to provide a facsimile apparatus that is equipped with a plurality of dither pattern matrices and has a function of selecting a combination of pixel density and transmission time according to the operator's request to perform halftone transmission or copy creation. The goal is to provide the following.

In order to achieve the above object, a facsimile apparatus according to the present invention is equipped with a plurality of storage devices and a 1gA mode selection device, and a combination of pixel density and transmission time is selected according to the operator's request. It has a function of transmitting or copying image information having halftones.

The plurality of storage devices are read-only memories having the necessary capacity and speed since they are used to store a corresponding plurality of dither pattern matrices. The mode selection device is necessary for halftone transmission or halftone copy making, and corresponds to one of the combinations of a plurality of pixel density modes and a plurality of transmission speed modes in image information having halftones, and selects a plurality of dither patterns. This is a switching device for selecting one of the matrices.

Next, a facsimile apparatus according to the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a facsimile machine constructed according to the present invention.

In FIG. 1, an analog image signal is applied via an input line 1 to a variable gain amplifier 2. In FIG.

7-1-Log image signal can be processed using CCD type line sensor or CC
This is obtained from a D-type image sensor or the like. The output signal of the variable gain amplifier device 2 is transmitted to first and second slice level determining devices f13.13, first and second binarization devices 4.14, and first and second dynamic range determining devices WL6. 10° first and second AD converters5.
9 each. The output signal of the variable gain amplifier ft2 applied to the first slice level determination device 3 and the first binarization device 4 is converted into a black and white binary signal and output to the line 23.

AD converter #5 of brush 1 is composed of a 4-bit AD converter. .

First dynamic range determination device 6 and first AD conversion device g! 15, the output signal of the variable gain amplifier 2 is converted into a 4-bit digital signal, that is, a 16-level digital image signal, and is applied to the dither signal converter 16 of F,1. The storage device 15 of the library 1 stores the dither pattern matrix K* in FIG. 2(a),
It consists of read-only memory (ROM).

The contents of the first storage device 15 are compared with the 4-bit digital signal applied to the dither signal converter 16 of the frame 1, and a dither pattern signal is formed and output to the line 17.

The second AD converter 9 includes a variable gain amplifier 2 by a second dynamic range determining device 10 and a second AD converter f9, each of which is composed of a 2-bit AD converter.
The output signal is a 2-bit digital signal, i.e. 4
The signal is converted into a level digital image signal and applied to the dither signal converter 19 of tl'C2.

The second storage device 18 stores the dither pattern matrix shown in FIG.
M).

1! ! The contents of the second storage device 18 and the 2-bit digital signal applied to the second dither signal converter 19 are compared, and a dither pattern signal is formed and output to the line 20.

The third storage device 21 stores the dither pattern matrix shown in FIG.
), a third storage device 21 and a second slice level determination device 1 are configured.
3, an analog dither pattern signal can be obtained. This signal is converted into a digital binary dither pattern signal by the second binarization device 14 and output to line B.

The image information signals applied to lines 17.20.22.23 are input to a mode selection device for selecting various modes of image information.

On the other hand, since the image information mode can be arbitrarily selected using a switch on the operation panel n, the image information mode selection signal is sent from the selection mode control device 25 according to the mode specified by the operator on the operation panel 27. is input to the mode selection device 24. Depending on the mode selection signal of the selection mode control device 5, the line 17.20.22%
One of the 23 is selected and output to the track song.

The black and white binary signal is output to the line 23, and the signal representing halftone is output to the lines 17, 20, and 22. Comparing the image information signal output to the lines 17, 20, and 22 with the black and white binary signal output to the line 23,
The former is the MH encoding method or MR.

It cannot be said that the compatibility with the encoding method is good, and the transmission time is generally long.

However, the image information signal on the line 17 is designed with a 4 x 4 dither pattern matrix, and the image information signal on the line 17 is dithered with a 2 x 2 dither pattern matrix, -
Since the image information signal of the route is dithered with a 1×16 dither pattern matrix, image information signals having nine different transmission speeds are obtained.

Considering the image information signals output to the lines 17, 20, and 22, the image information signal on line n has the highest transmission speed, and the transmission speed decreases in the order of line addition and line 17. On the other hand, the image quality is the highest for the image information signal on line 17, and decreases in the order of line 20 and line n. The operator should consider the trade-off between transmission time and image quality, and perform the above four steps.
One of the image information signals of class s can be arbitrarily selected.

That is, when making a copy, the 4x4 dither pattern matrix with the best image quality is selected and copied.
When transmitting, it is possible to select a 1x16 dither pattern matrix for transmission. If such a selection is made, the quality of one transmitted signal will be inferior to the quality of a recording signal, but the necessary information will be transmitted in a short time. can be transmitted.

On the other hand, if a 2×2 dither pattern matrix is selected for transmission or copying, an intermediate transmission speed and intermediate image quality can be obtained.

If mode selection signals for image information are set in the selection mode control device 25 in advance in correspondence with each operation mode,
An appropriate dither pattern matrix can be automatically selected within the facsimile machine without giving any instructions from the operation panel 27.

The ta1-first-storage device 15.18.21 is configured with a read-only memory (ROM), but it is also possible to configure it with an erasable read-only memory or temporary memory.

As described above, according to the present invention, a plurality of dither pattern matrices are provided inside a facsimile machine, and one of the plurality of dither pattern matrices can be arbitrarily selected and used. Therefore, since the combination of image quality and transmission time can be arbitrarily selected according to the operator's request, it has a high utility value, can contribute to labor saving, and is highly economical.

In other words, when good image quality is required, such as when making copies, you can select high pixel density, and when high-speed work, such as image transmission, is required, you can select high transmission speed. Although it is a facsimile machine, it can perform the functions of several facsimile machines.

Furthermore, since an automatic mode selection function for automatically selecting these requests can be provided, it can also contribute to labor saving.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a facsimile machine according to the present invention, and FIG. 2 shows an arrangement of a plurality of dither pattern matrices stored in a plurality of storage devices used in FIG. It is a diagram. 2... Variable gain amplification device 3.13... Slice level determination device 4.14...
Binarization device 6.10...Dynamic range determination device 5.9...
・AD conversion device 16.19...Dither signal conversion device 15.18.21...Storage devices...Mode selection device 25...Selection mode control device 27...Operation panel 1.7.8 .11.12.17, Ka, 22, Phantom, Ka...
・Line patent applicant: NEC Corporation Representative: Hisashi Inoro, patent attorney (Figure 2 (C1) (b) (C)

Claims (1)

[Claims] A facsimile device equipped with a function for transmitting or copying image information having pseudo halftones obtained by a dithering method includes a plurality of storage devices for storing a plurality of dither pattern matrices, and a plurality of storage devices for storing the plurality of dither pattern matrices, and a plurality of storage devices for storing the plurality of dither pattern matrices; mode selection of selecting one of the plurality of dither pattern matrices corresponding to one of the combinations of a plurality of pixel density modes and a plurality of transmission speed modes of the image information when transmitting or copying image information having the image information. A facsimile device comprising: