JPS6282889A - Transmission equipment for still image - Google Patents

Abstract

PURPOSE:To attain optimum imaging prevented from the saturation of a high light level at the time of imaging on the receiving side by inserting a signal corresponding to the maximum level in a still image in front of the still image signal. CONSTITUTION:A graphic signal including a white level period is sent from the transmission side. The signal is inputted from a terminal 17 and guided into a synchronizing pulse extracting circuit 18 and a gain setting circuit 19. The output of the circuit 19 is inputted to a white level detecting circuit 20 and an exposure driving circuit 21. The circuit 20 detects a level A in the white level period, and if a video signal level in the successively inputted image period is 8-bit quantization, sets up the gain of the circuit 19 so that the level becomes the maximum level 255. The obtained video signal is inputted to the circuit 21 and the quantity of exposure is found out as an analog value. The quantity of exposure is finally applied to an exposure element 22 to expose a photosensitive surface. The synchronizing pulse with a period T extracted from the circuit 18 is compared with a pulse corresponding to a rotational phase by a phase comparator 25 and the compared output controls a motor driving circuit 26 and makes a photosensitive drum motor 23 synchronize with a system synchronizing pulse.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a still image transmission device for transmitting video signals such as television signals via a telephone line or the like.

Background In recent years, systems have been considered in which TV signals are transmitted using telephone lines and the like, and the receiving side prints the signals using photographic paper or a video printer. FIG. 1 is a schematic diagram showing the entire system.

1 is a rotating magnetic sheet, and 2 is a motor for rotating it. A reproducing head 3 is disposed on the rotating magnetic sheet 1, and one field or one frame of still images is reproduced here.

The playback signal is input to the video processing circuit 4, where N
The signal is converted into a form such as a TSC signal or a line sequential signal. This video signal is displayed by a motor 5 and input to an RGB matrix 6. In the RGB matrix 6, the reproduced video signal is subjected to matrix calculation to obtain R, G, and B components. Furthermore, these signal components are subjected to complementary color conversion and γ in the image processing circuit 7.
Processing such as correction and masking is performed. This output is A/
It is digitized by the D converter 8, and is converted to, for example, 8 bits.
It is made into a child, and it is made into a child at 256 levels. These Y, 2. Mg and Cy data are sequentially stored in the frame memory 9 for each operation described later, and this data is read out in accordance with the transmission rate of the transmission line. At this time, a phase synchronization signal is added to the data in the transmission signal forming circuit 10 so that the receiving side can print or make a plate at the same timing.

11 forms a transmitter, the output of which is transmitted via a communication line K to the receiving side.

On the receiving side, the transmitted data is temporarily stored in the frame memory, and is sequentially A/D converted to Yl (yellow) and CY.
(cyan) and Mg (magenta), and output it to the monitor 16 via the NTSC encoder 15.
At the same time, the image is also supplied to the printing device 14. In the printing device 14, the obtained Yu, Cy, and Mg signals are used to control the amount of ink when exposing a photosensitive material for each color component, for example, if the negative is an inkjet print.

When obtaining a print at this time, in addition to synchronizing the sending and receiving systems, settings must be made so that the print data makes effective use of 8 bits and 256 gradations.

Purpose> In order to fulfill the above requirements at the time of transmission, the present invention also transmits the level of the highest brightness or whitest part of the image to be printed, and sets this level to the full level for subsequent transmission. The present invention aims to provide a still image transmission device that determines the level of received printing data based on this data.

<Embodiment> FIGS. 2 and 3 are diagrams for explaining an embodiment of the present invention. FIG. 2 shows the form of the transmitted signal, in which a pulse for system synchronization appears first.

In this case, for example, the printing device is formed of a cylindrical photosensitive drum and records the water moline sequentially on photographic paper or printing paper wrapped around the drum, and if this motor rotation period is T, then synchronization is performed. The pulse for
appears in During this period, the rotation motor is phase-locked.The zero-order white level signal period comes, and the whitest part of the image is set at the optimum level.For example, in the case of 8-bit quantization, this level (Fig. 2A) is set to 255. . Subsequently, in the image period, image signals for one frame appear continuously in accordance with the transmission rate.

However, in order to create printing negatives for yellow, magenta, and cyan, respectively, Yl and Mg are required.

Since each output signal of cy is required separately, the second
The signal shown in the figure is presented a total of three times before the image signal of each color.

FIG. 3 is a concrete block diagram of the printing device 14 on the receiving side in FIG.

The signal shown in FIG. 2 is input from the terminal 17, and is led to a synchronizing pulse extracting circuit 18 and a gain setting circuit 19. The output of the gain setting circuit 19 is input to a white level detection circuit 20 and an exposure drive circuit 21. The white level detection circuit 20 detects level A of the white level signal period in FIG. 2, and the video signal level of the subsequently input image period is, for example, 8
In the case of bit quantization, the gain of the gain setting circuit 19 is set so that the maximum level is 255. The video signal thus obtained is input to the exposure drive circuit 21, and the exposure amount is determined in an analog manner. Finally, this amount of exposure is applied to the exposure element 22 to expose the photosensitive surface.

Further, the synchronization pulse with period T extracted by the synchronization pulse extraction circuit 18 becomes one input signal of the phase comparison circuit 25,
A pulse corresponding to the rotational phase obtained from the PG head 24 of the photosensitive drum 23 is input as the other input, and a phase comparison circuit 25 performs a phase comparison between these two manual forces.

The output corresponding to the phase error obtained here controls the rotation of the motor drive circuit 26, and rotationally synchronizes the photosensitive drum motor 23 with the system synchronization pulse.

In the embodiment described above, a photosensitive negative is created on a photosensitive drum, but an inkjet printer or other printer device may also be used.

Furthermore, although the level detected by the self-level detection circuit 19 is set to 255 by, for example, 8-bit H conversion, it may be set to a slightly lower value, taking into account the possibility of level saturation.

Effects> As explained above, according to the present invention, since the maximum level signal of the transmitted original image is added, saturation of the highlight level does not occur at the time of printing on the receiving side, and optimal image printing can be performed.

Furthermore, even if the dynamic range of the transmitted original image is narrow, or even if the transmission level varies depending on the line, a received image with a wide dynamic range can always be obtained.

[Brief explanation of drawings]

FIG. 1 is an overall system diagram for transmission and reception, FIG. 2 is a diagram showing the format of printing signals, and FIG. 3 is a concrete block diagram of the printing apparatus.

Claims (1)

[Claims] A still image transmission device for transmitting a still image signal from a transmitting side to a receiving side, characterized in that a signal corresponding to the maximum level in the still image is inserted before the still image signal.