JPS60134665A - Facsimile equipment - Google Patents

Abstract

PURPOSE:To reduce code generating bits without changing pitch of subscanning and to improve the efficiency of compressing by making two-dimensional band compression for a picture signal of simple paintings and calligraphic works. CONSTITUTION:At the time of completion of writing of a scanning line, it is stored in a memory of the number of change point 2 whether the number of change points of black and white picture elements exceeds a some value or not as information indicating complexity of picture signals of each block. When sending data of each block successively, a reading circuit 10 sends out signals of present line for signals of complicated pictures or calligraphic works, and sends out signals of corresponding block of a line of right before for picture signals of simple paintings and calligraphic works respectively to a band compression circuit 9 depending on the number of change points in each block. When the paintings and calligraphic works are of simple pattern, the line can be converted to signals of high compression efficiency without putting forward the deterioration of picture signals in above-mentioned band compression circuit 9 by converting each line to signals resembling to immediately preceding line.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a facsimile machine, and particularly to one that performs automatic vertical resolution switching.

[Prior art]

Conventionally, when performing automatic vertical resolution switching in this type of device, the number of changing points of black pixels and white pixels of one line is counted, and for lines where the number of changing points is less than a predetermined number, the vertical resolution is coarsened and the image signal is changed. was reading.

That is, in a conventional image signal reading device, - the number of change points of black pixels and white pixels of the image signal in a scanning line is counted, and if the number of change points is less than a predetermined value, it is determined that the calligraphy is a simple pattern. to coarsen the sub-scanning pinch and read the next line. When transmitting a line signal with a coarser sub-scanning pitch, a special line synchronization signal that can identify that the sub-scanning pitch has changed is encoded and transmitted to the receiving side together with the image signal of the line. I was doing it.

Conventional facsimile machines are configured as described above, and by calculating the number of changing points of black and white pixels in the entire scanning line of one line, the pinch of the sub-scanning is made coarser and the transmission time is shortened. If there is a partially fine pattern in the calligraphy or drawing, it may not be possible to judge it sufficiently and the sub-scanning pinch may be applied coarsely.Also, if the sub-scanning pitch is made coarse, the line may be changed to the normal pitch. It was necessary to prepare multiple line synchronization signals so that the lines could be identified.

[Summary of the invention]

The present invention was made in order to eliminate the above-mentioned drawbacks of the conventional method. Each scanning line is divided into blocks of a fixed length, and the number of changing points of white and black pixels for each block is counted. , for the section where the number of change points is less than a predetermined value, the image signal of the section of the scanning line immediately before the scanning line is read out from the line memory instead of the image signal of the read line, and It is an object of the present invention to provide a facsimile apparatus which can reduce code generation bits without changing the sub-scanning pitch and improve compression efficiency by performing two-dimensional band compression.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a facsimile apparatus according to an embodiment of the present invention. In the figure, 8 is a photoelectric conversion circuit as a reading circuit that scans the surface of a document and reads information on calligraphic strokes, and 3 and 4 are 1, respectively.
A line memory capable of storing a line's worth of image signals; 1 is a change point counter circuit that divides a scanning line into sections of a fixed length and counts the number of change points of pixels included in each section; 10 is a line memory 3゜4 readout circuit reads out the image signal of the corresponding section from the line memory that stores both signals of the current scanning line for the section where the number of change points exceeds a predetermined value, and reads out the image signal of the corresponding section when the number of change points falls below the predetermined value. Regarding a section, the signal of the section is read out from the other line memory which stores the image signal of the immediately preceding line. In the continuation circuit 10, 2 is a change point number memory, 7 is a write/read timing switching circuit, 6 is an n frequency divider circuit, and 5 is a memory for one of two line memories 3.4 for each divided block. This is a switching circuit for reading out signals.

Next, the operation will be explained.

The switch 20 is driven by a drive circuit (not shown) and transfers the image signal from the photoelectric conversion circuit 8 to the line memory 3 line by line.
．． 4 alternately. Memory write pulse a generated by the write/read timing switching circuit 7 (Figure 2+a)
) is frequency-divided by n by the frequency dividing circuit 6, and the timing signal b (see Fig. 2 (bl)) is obtained by dividing one line by n.
is creating.

Now, in the period tw shown in FIG. 2 (0), the image signal of the line immediately before the current scanning line has already been stored in the memory 4, and the image signal C of the current line (see FIG. 2 (see C1) is photoelectrically converted. Assume that the signal is input from the circuit 8 to the line memory 3.

During this period tw, the number of black and white changing points of the image signal of the current line is counted for each block by the changing point counting circuit 1, and when the counting result is greater than a certain value, it is set as a logic level 11'', and when it is smaller, it is set as a logic level. Each logic level is stored as level 1lO1l in the change point number memory 2. Therefore, when writing of one scanning line is completed,
The change point number memory 2 stores whether the number of change points of black and white pixels is greater than a certain value as information indicating the complexity of the image signal of each block.

Next, when reading out the four-picture signal of the current line written in the line memory 3 during the period tr in FIG. 1'', the block is a complex calligraphic stroke, and the data in the line memory 3 is output to the band compression circuit 9 for one block via the switching circuit 5. Also, the data in the change point number memory 2 is In this case, the switching circuit 5 is controlled as a simple calligraphy pattern, and the data of the corresponding block of the previous line is read out from the line memory 4 instead of the data of the current line.

In order to send the data of each block sequentially in this way, the readout circuit 10 transmits the signal of the current line to the image signal of the complicated calligraphy and drawings depending on the number of change points of both signals in each block.
For both simple calligraphy and drawing signals, the signals of the corresponding blocks in the immediately preceding line are sent to the band compression circuit 9, respectively.

By the way, it is known that in a two-dimensional band compression method such as a modified read method, the code of an image signal similar to the previous line becomes shorter. Therefore, when the calligraphy and drawings have a simple pattern as in this embodiment, by converting each line into a signal similar to the line immediately before it, deterioration of the image signal in the band compression circuit 9 can be made less noticeable. can be converted into a signal with good compression efficiency.

〔Effect of the invention〕

As described above, according to the present invention, a scanning line is divided into blocks of a constant length, and each block is divided into white blocks.

The number of changing points of black pixels is counted as the number of stitches, and for sections where the number of changing points is less than a predetermined value, the image signal of the corresponding section of the immediately previous line is taken as the image signal of the current scanning line. Since the two-dimensional band compression is performed using the two-dimensional band compression, the pitch of the sub-scanning is changed. This has the effect of reducing the number of code generation bits, increasing compression efficiency, and minimizing deterioration in image quality of transmitted documents and images.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a facsimile apparatus according to an embodiment of the present invention, and FIG. 2 is a diagram showing waveforms and operation timings of various parts of the apparatus of FIG. 8... Photoelectric conversion circuit (reading circuit), 1... Change point counting circuit, 3.4... Line memory, 10... Reading circuit, 9... Band compression circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Masuo Oiwa

Claims (1)

[Claims] (1) In a facsimile machine that transmits binary images, there is a reading circuit that scans the document surface and reads calligraphic strokes, and a system that sequentially switches and stores image signals from the reading circuit line by line.
a line memory, a changing point stitch number circuit that counts the number of changing points of pixels in each section obtained by dividing one scanning line from the reading circuit into each section, and the counted changing point number. For a section in which the value exceeds a predetermined value, the image signal for the section is read out from the line memory that stores the image signal for one scanning line that includes the section, and for a section where it is lower than the predetermined value, the image signal for the immediately preceding scanning line is stored. 1. A facsimile apparatus comprising: a readout circuit for reading out an image signal of a corresponding section from the other line memory in which the facsimile apparatus is provided; and a band compression circuit for two-dimensional band compression of the output of the continuous output circuit.