JPS62200978A - Transmission system for halftone image data - Google Patents

Abstract

PURPOSE:To efficiently transmit data by transmitting the data of a halftone image in a gradation code. CONSTITUTION:In a transmission side, a gradation code forming means 13 for converting the halftone image data into the gradation code corresponding to the data is provided and the halftone image data read in an image sensor is converted into the gradation code and transmitted. In a receiving side, a demodulation means 16 for demodulating the gradation code received from the transmission side to the halftone picture data is provided and by the output of the demodulation means 16, the halftone image is reproduced. Thereby, the quantity of the transmission data can be largely reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a halftone image data transmission method applied to a device that handles halftone images, such as a facsimile machine.

(Prior Art) Conventionally, in a facsimile machine, a document image including halftones is read by an image sensor such as a COD element on the sending side, and the read halftone image data is encoded using a predetermined encoding method such as MH code or MR code. halftone image data based on this compression code is transmitted to the receiving side, decoded by a decoding unit on the receiving side to restore it to the original medium tone image data, and transferred to the recording unit. The system is configured to reproduce the same image as the original image on the sending side.

(Problem to be solved by the invention) However, when considering the transmission efficiency of halftone image data, for example, if one pixel is set as 4×4 micropixels, the threshold value of each micropixel and the Compare with the data 1
In a system that generates halftone data of 6 gradations, encodes and transmits this halftone data, there are slight differences depending on the pattern of lffl1 values, but the data D before encoding and the data after encoding are different. The difference was not very large, and there was a problem that the transmission efficiency was not good.

It is an object of the present invention to solve these problems and provide a method for transmitting halftone images and data with high transmission efficiency.

(Means for Solving the Problems) The present invention provides a gradation code generation unit on the transmitting side for converting halftone image data into a gradation code corresponding to the data, It is constructed so that the tone image data is converted into tone code and transmitted, and
The receiving side is provided with demodulating means for demodulating the tone code received from the transmitting side into halftone image data, and the halftone image is reproduced by the output of this demodulating means.

(Function) The halftone image data read by the image sensor is converted into a tone code by the tone code generating means and transmitted. On the receiving side, the gradation code is converted into the original halftone image data by a demodulation means, and reproduced on the recording section, display section, etc. as the same halftone image as the original image.

(Embodiment) FIG. 1 is a block diagram showing an embodiment in which the present invention is applied to a facsimile machine. In the same figure, 11
12 is composed of a CGDI child, etc., and reads the original image, and 12 is the halftone image data of the read original image.
13 is a gradation code generation unit that converts the halftone image data read by the reading unit 11 into a gradation code and outputs it; 14 is a destination facsimile device; 15 is a printing unit that records the decoded halftone image data as a visible image on recording paper; and 16 is a printing unit that decodes the coded halftone image data received from the other party's facsimile machine. WW to the original halftone image data! The gradation code demodulation unit 17 is the main unit that controls the entire device! hlJI Department, 18
1 is a modem, and 19 is a line connection control unit (NCU) for making a line connection with the other party's facsimile machine.

FIG. 2 is a flowchart showing the sequence of pre-procedures up to the start of image data transmission. Reference numerals 21 and 22 represent pre-procedure command signals sent from receiving and transmitting facsimile machines, respectively. NSF/DIS and NSS/ It is DC8. 23 is a training signal for the modem 18, 24 is a command signal indicating that reception is ready, and 25 is image data.

FIG. 3 is a control flowchart of the sending facsimile device (hereinafter referred to as the transmitter), and FIG. 4 is a control flowchart of the receiving side facsimile device (hereinafter referred to as the receiver).

The operation of the facsimile machine shown in FIG. 1 to which the present invention is applied will be described below with reference to FIGS. 2 to 4 as appropriate.

First, when the main control unit 17 of the transmitter determines that a request to transmit halftone image data has been given in step 31, the main control unit 17 receives the line while controlling the NCU 19, and connects normally. Perform pre-fax procedures.

When the receiver receives the N5F1015 signal 21, it analyzes the signal and determines whether the recipient has the transmission capability using the halftone image data transmission method using tone codes (hereinafter referred to as the "new halftone transmission method"). The decision is made in step 32. If it is determined that the receiver has the capability, the transmitter specifies the new halftone transmission method with parameters and sends the NSS/DOS command 22 to the modem 18.
υJυD is shifted so that the training signal 23 of υJυD is transmitted.

When receiving the reception ready signal (CFR) 24 from the reception target, the process moves to step 33, gradation code transmission processing, and activates the gradation code generation unit 13 instead of the encoding unit 12, which was conventionally controlled to start. control, and generates a gradation code according to the gradation of the halftone image. This generated gradation code is taken into the main control section 17, and the modem 18 and NC
It is sent out to the line through U19.

On the other hand, when Uke@4 receives the NSS/DOS command signal 22, it analyzes this command signal in step 41,
When the new halftone transmission method is detected, the tone code demodulation section 1 replaces the decoding section 14 that was previously controlled to start up.
6, and the process proceeds to step 42, gradation code demodulation processing. Then, the halftone image data obtained by demodulation is printed out as a visible image while controlling the activation of the printing section 15 in the printing process of step 44. Thereafter, the gradation code demodulation process in step 42 and the printing process in step 44 are executed until it is determined in step 45 that the reception is complete.

On the other hand, the operation when it is determined in step 32 that the receiver does not have the capability of the new halftone transmission method will be described. In this case, the main/sub υ1 unit 17 of [transmission] moves from step 32 to tL31 of step 34, and the halftone image data read by the reading unit 11 is expanded into the conventional bit pattern and sent to the encoding unit 17. send to Then, the halftone image data is encoded into a code such as an MH code or an MR code, and then passed through the modem 18 and one NCU unit and sent to the frontispiece. This is the bit pattern transmission process in step 34, which uses a transmission method similar to that of conventional facsimile machines, and is combined so that it can transmit data even to devices that do not have the new halftone transmission method. The receiver process corresponding to the bit pattern transmission process in this case is step 4.
3 decoding process, NCU1'j, modem 18. The data passing through the main control unit 17 is transferred to the decoding unit 14,
After being decoded here, it is transferred to the printing unit 15 and printed as a visible image. At this time as well, the decoding process in step 43 and the printing process in step 44 are repeated until it is determined in step 45 that the data transfer is complete, similar to the conventional facsimile machine.

The above is an explanation of the operation of the embodiment, but if we consider the data transmission efficiency, for example, 16
When transmitting a halftone image, although there are differences depending on the dither pattern, the data representation after encoding is on average approximately the same level as before encoding.

However, in this method, two block codes can be expressed in one byte, so the maximum amount of data is reduced to 1/8, and the time required for data transmission is also reduced to 1/8.

Therefore, it is possible to further reduce the transmission data i and further improve the transmission efficiency by devising the method of determining the gradation code.

Note that when transmitting using a gradation code, this occurs on the transmission line. It is conceivable that the visible image will be greatly disturbed by transmission errors, but this can be solved by adding a code error correction circuit.

Furthermore, the present invention is applicable not only to facsimile machines but also to all devices that handle halftone images.

[Effect of the Invention 1 As explained above, according to the present Komei, data of a halftone image is transmitted using a gradation code. This method greatly reduces the number of pixels and enables efficient transmission of halftone image data, which is extremely beneficial in terms of saving transmission time and costs.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a facsimile apparatus to which the present invention is applied, FIG. 2 is a sequence diagram showing a control procedure executed before the start of image data transmission, and FIGS. 3 and 4 are on the sending side. and a flowchart showing image data transmission and reception operations on the receiving side. 11...Reading unit 9.12...Encoding unit, 13...
- Gradation code generation section, 14...Decoding section, 15...
Printing section, 16... Gradation code demodulation section, 17... Main control section, 18... Modem. Figure 1 Figure 3

Claims (1)

[Scope of Claims] A halftone image data transmission method in which a halftone original image is read by an image sensor on a transmitter side, the image data is encoded according to a predetermined encoding method, and is transmitted to a receiver side, comprising: A gradation code generating means for converting halftone image data into a gradation code corresponding to the data is provided on the side, and the halftone image data read by the image sensor is converted into a gradation code and transmitted. The receiving side is provided with a demodulating means for demodulating the gradation code received from the transmitting side into halftone image data, and the halftone image is reproduced by the output of the demodulating means. A transmission method for halftone image data.