JPH0461585A - Picture transmitter - Google Patents

Abstract

PURPOSE:To obtain a reception picture with high quality by providing a means converting a signal into a time series signal while revising a scanning direction of a pattern for each of several picture elements when plural picture data forming the pattern are sent. CONSTITUTION:A picture data is fed to a picture memory 101 and the picture data by one pattern is stored once in the picture memory 101. Then a picture data of a 1st line is transferred to a line buffer 102A from the picture memory 101 and a picture data of a 2nd line is transferred to a line buffer 102B. Then a picture data of a 1st picture element is transferred to a MODEM 103 from a buffer 102A and modulated and the result is sent through a transmission line 300. Succeedingly, the picture element dat of the 1st picture element is transferred from the buffer 102B to a MODEM 103, in which the data is modulated and the result is sent through the transmission line 300. Succeedingly, the picture data is transferred to the MODEM 103 and then the result is sent.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides a method for modulating image data into an audio band signal, etc., and transmitting it through a narrow band transmission path such as a general telephone line, for example, in a videophone, etc. Regarding equipment.

``Prior Art'' In an image transmission device that uses a low-speed, narrow-band communication path such as a general telephone line, a modem modulates screen data into an audio band signal and transmits the signal.

In this case, as a means to speed up the transmission (i) by using data compression to reduce the amount of data to be transmitted, and by utilizing the fact that image data has redundancy that can be tolerated even if the brightness and hue change to a certain extent, There are means to increase the transmission speed on the premise of allowing errors.

Like the latter, in an image transmission device that directly uses the redundancy of image data to speed up transmission, when transmitting multiple pieces of image data that make up a screen, the first line is Next, the second line was scanned in the same way from left to right, and converted into a time-series signal (section 5).

[Problem to be solved by the invention] Conventional image transmission device as described above! In the scanning method, image data of pixels that are agonized to the left and right are transmitted continuously, but image data of pixels that are adjacent to each other vertically is transmitted at intervals of (number of pixels in the horizontal direction - 1) data number. I can't stand it. Therefore, due to the characteristics of the transmission signature, the transmitted data may be inferior.
The influence of the force on the body and the lateral force is particularly noticeable in the lateral direction.9 This greatly deteriorates the quality of the transmitted image.

Now, consider the case where luminance data is transmitted by AM modulation. The maximum amplitude is assigned to the maximum brightness, the minimum amplitude is assigned to the minimum brightness, and data of 8 gradations from "0" to "7" is transmitted.

When transmitting at high speed in a narrow area, if the line condition is poor, the data rises slowly, so if the brightness changes rapidly, the changes in the transmitted data may not be able to catch up. This appears as a deterioration in resolution on the receiving side.

For example, as shown in Fig. 6, an original image whose brightness changes rapidly from an initial brightness of "0" to a maximum brightness of r-7J along the vertical direction, that is, the boundary line in the sub-scanning direction, is transmitted. shall be.

FIG. 7 is an enlarged view of the boundary portion of the original image, and shows the brightness of each pixel.

In this case, the transmission data at the boundary portion is 0, 0. 0. 0. 7. 7 7
7, resulting in a transmission waveform as shown in FIG.

On the other hand, the received waveform IJ at the boundary part becomes as shown in FIG. 9, and the received data at the boundary part is 0, 0. 0
．． 0. 1 3. It becomes 5 7.

FIG. 10 is an enlarged view of the boundary portion of the received image and shows the brightness of each pixel. In other words, on the receiving side, the brightness changes gently over several pixels at the boundary.
If the resolution of the received image is reduced to 1/p in the vertical original image, the resolution of the received image is m/p.
The resolution in the horizontal direction is significantly degraded by p pixels on the pixel surface and n pixels.

Therefore, in the present invention, it is possible to prevent a significant deterioration of the resolution in the negative direction and obtain a high-quality received image.

"Means for Solving the Problems" The present invention is an image transmission device that modulates image data into an audio band signal or the like and transmits the image data. A means to scan while changing the scanning direction every few m elements and convert it into a time-based q signal!
- #l Also, it is intended to two-dimensionally diffuse data deterioration in the transmission path.

[Operation] In the above configuration, the screen is scanned while changing the scanning direction regularly every few pixels to form a time-series signal that becomes the transmission data, so even if data deteriorates in the transmission path, the time-series signal is not transmitted. This influence is dispersed in both the horizontal (main scanning) and vertical (sub-scanning) directions in the received image, making it possible to obtain a received image of higher quality than before.

[Embodiment] An embodiment of the present invention will be described below with reference to FIG.

In the figure, 100 is a transmitting side device, 200 is a receiving side device, and 300 is a transmission path such as a general telephone line.

The transmitting unit 2100 includes an image memory 101, line buffers 102A and 102B, a modem 103, and a CPU.
104 is provided. The loading and reading operations of the image memory 101, line buffers 102A and 102B, and the modulation operation of the modem 103 are controlled by the CPU 104.

The receiving side bag f200 includes an image memory 201, line buffers 202A and 202B, a modem 203, and a CPU 20.
4 is provided. Writing and reading operations of the image memory 201 and line buffers 202A and 202B, and modulation operations of the modem 203 are controlled by the CPU 204.

Next, the operation will be explained.

First, the operation of the transmitting FM device 2100 will be explained.

Image data (digital data) from a video camera, scanner, etc. is supplied to an image memory 101, and image data for one screen is temporarily stored in this image memory 101.

Then, from the image memory 101, the line buffer 102A
The image data of the first line is transferred to the line buffer 102B, and the 'iIigA data of the second line is transferred to the line buffer 102B.

And korekiyoniba sofa l 02A, 102B
After the image data is transferred to , the image data of the first pixel is transferred from the buffer 102A to the modem 103, modulated, and transmitted using the transmission path 300. Next, the pixel data of the first pixel is sent to the modem 10 from the buffer 102B.
3, modulated, and transmitted via transmission path 300. Hereinafter, the image data of the second pixel of the rose 2A 102B, the image data of the second pixel of the buffer 102A, the image data of the third pixel, the image data of the third pixel of the buffer 102B, the image data of the fourth pixel, and so on. The image data is transferred to the modem 103 and transmitted in this order.

When two lines of image data are transmitted in this way, the image data is also sent to the buffer from the image memory 101] 02A, 10
Two lines of image data are transferred to 2B, and similarly, image data for each pixel is transferred to modem 103 and transmitted. This is repeated for one screen, and the image data for one screen stored in the image memory 101 is transmitted.

In this manner, in this example, the screen is scanned while being changed in the horizontal and vertical directions for each pixel in the scanning direction, thereby forming a time-series signal that becomes transmission data (see FIG. 2).

FIG. 3 is a flowchart showing the operation of the above-mentioned transmitting device 100.

Here, the number of pixels on one screen is M (horizontal) x N (vertical). However, N and lvH are even numbers. m from left
The image data of the pixel, the n-th pixel from the top, is a n , a
It is written as.

In the figure, n is set to 1 in step 10. At this time, the image data 101 stores one screen worth of image data to be transmitted.

Next, in step 11, m is set to 1.

Then, from the image memory 1.01, the buffer 102A,
102B, the image data of the n-th line and the n-1-1th line are transferred, respectively.

Next, in step 12, image data a is sent from the buffer 102.4. , , are transferred to modem 1.03 and transmitted.

Next, in step 13, the image data eLn-+, m, ah-l, +-l are successively transferred from the buffer 102B to the modem 103 and transmitted.

Next, in step 14, the image data a n, a-1, an, n, 2 are successively transferred from the buffer 102A to the modem 103 and transmitted.

Next, in step 15, m is set to m+2, and then in step 16, it is determined whether m>M or not. If m>M is not true, return to step 13 and
The same operation as described above is repeated.

In step 16, if m>M, step 17
Then, image data a0 is sent to modem 1 from buffer 102A.
03 and is transmitted. This allows 1im
All of the two lines of image data transferred to the memory 101 and buffers 1O2A and 102B are transmitted.

Next, in step 18, n is set to n+2, and then in step 19, it is determined whether n>N.

If n>N, return to step 11 and perform the next 2
Image data transfer for one line is started.

In one step, when n>N, the image memory 1
This means that the transmission of all the image data for one screen stored in 01 has been completed, so the transmission operation ends.

Next, the operation of the receiving device 200 will be explained.

The signal from transmission line 300 is supplied to modem 203 and demodulated. The received data from this modem 20B is the first pixel of the line buffer 202A, the line buffer 202
The data is transferred in this order: the first and second pixels of B, the second and third pixels of the buffer 202A, and so on.

In this way, two lines of image data are received,
Once stored in the buffers 202A and 20.2B, these two lines of image data are transferred to the image memory 201.

This operation is repeated for one screen, and the image memory 20
1 stores image data for one screen. Then, this one screen worth of image data is sequentially read out and output, and the received image is displayed on a monitor (not shown).

In this manner, in the present example, the transmitting device 100 scans while changing the screen power scanning direction horizontally and vertically for each pixel to form a time-series signal that becomes transmission data.

Therefore, when the receiving device 200 rearranges the received data to form one screen worth of image data, the influence of data deterioration on the transmission path is distributed both horizontally and vertically.

Fig. 4 shows the boundary part of the received image when transmitting the original image as shown in Fig. 6 [2I] and an enlarged representation of fSpfi. You can see that it becomes sudden.

Therefore, according to this example, a high-quality received image can be obtained even if a transmission path with poor conditions is used.

For example, due to data deterioration in the conventional transmission path, the horizontal resolution decreases to 1/p, and the resolution of the received image becomes m/p pixels x
Assuming that there are n pixels, in this example, the horizontal and vertical resolutions are respectively 2.・The resolution of the received image is 2 m 7ρ pixels x 2 (1
, , / p pixels, and the quality of the received image fill is greatly improved.

[Effects of the Invention] As explained above, according to the present invention, a time-series signal that becomes transmission data is formed by scanning the screen while regularly changing the scanning direction every few pixels, so that the transmission path even if data deterioration occurs.

This influence is distributed in both horizontal (main scanning) and #11 (sub-scanning) directions in the received image. Therefore, even if 5+ bad transmission paths are used, a high-quality received image can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIGS. 2 to 4 are diagrams for explaining its operation, and FIGS. 5 to 10 are diagrams for explaining a conventional example. 100 Transmission side device 200 Receiving side device 101.201 102A, 102B 1, 0 3 Transmission path image memory 202A, 202B Line barrier modem PU

Claims (1)

[Claims] (1) In an image transmission device that modulates and transmits image data into an audio band signal, etc., when transmitting multiple pieces of image data that make up a screen, the screen is scanned while changing the scanning direction of the screen every few pixels. What is claimed is: 1. An image transmission device comprising means for converting data into a time-series signal to two-dimensionally diffuse data deterioration in a transmission path.