JPH0192828A - Automatic setting system for threshold level - Google Patents

Abstract

PURPOSE:To automatize the setting of threshold levels by setting up the threshold level for reading out a video signal for hard copy recording based on an output from a data control part. CONSTITUTION:An analog video signal by one picture is read out by a video signal reading part 1 at N threshold levels set up with a prescribed level internal and the number of data existing between respective levels is counted up by a counter 2. A data control part 3 calculates and outputs threshold levels to be newly allocated from the ratio of the numbers of data in the counter to assign M threshold levels set up so that the interval between the threshold levels having more data is narrowed in accordance with the counted result. The reading part 1 is controlled by the output of the control part 3, the video signal read out in the 2nd time is stored in a picture memory 4 and the memory data are outputted as a hard copy record. Thus, the setting of threshold levels can be automatized.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a threshold level setting method for reading an analog video signal input to a hard copy device with a gradation function, and a method for automatically setting the threshold level. For the purpose of A data control unit is provided that allocates M threshold levels (M≧N) that narrow the threshold level interval of the one with the larger number of data in accordance with the counted results, and the output of this data control unit The system is configured to set a threshold level for reading a video signal for hard copy recording.

[Industrial application field]

The present invention relates to a method for setting a threshold level for reading an analog video signal input to a hard copy device with a gradation function.

In computer-applied image creation systems, various color or monochrome constituent images are created as graphic images on a display screen and then printed out. The hard copy recording that is the printed output naturally requires a gradation corresponding to the graph ink image, and a gradation hard copy device is required for this purpose.

However, since there was no suitable method, conventionally the threshold level had to be set manually only when necessary.

However, this manual threshold level setting takes time to adjust and results in poor recording, so there is a need for a threshold level setting method that can be set automatically.

[Conventional technology]

FIG. 6 shows a device configuration diagram of the image creation system.

This system consists of five devices: a display device 31, a hard copy device 32, a control device 33, a host CPU 34, and a storage device 35. The display device 31 includes a keyboard 31 that provides input data necessary for creating the composition image.
-2 and is input from the light pen 31-3 and the monitor 31-
1, and the video signal is sent to the hard copy device 32, where the magnitude of the level is read by a four-story steel, converted into a dot signal, and printed out as a hard copy record.

Note that the control device 33 is a device for controlling the display device 31, and the host CPU 34 and the storage device 35 are devices for controlling the control device 33 and operating the entire system efficiently.

A conventional method of reading video signals in hardcopy device 32 is illustrated in FIGS. 7 and 8. In the figure, the vertical axis is the video signal level ratio (%), which is expressed as a ratio of 0% when there is no video signal and 100% when the level is maximum, and the horizontal axis is the time of the video signal. It is. Furthermore, the seventh
．． Both figures 8 are represented on the same scale. In Figure 7, the threshold level S1 for reading the video signal level is set to 20%, S2 is set to 40%, S3 is set to 60%, and S4 is set to 20%.
is fixed at 4 levels of 80%. The video signal (A) in this example is generated at fixed time intervals 1. 0-100% at
I have selected an example that changes to 5 steps.

The number of data read is proportional to the time interval t, the same value is counted for each number of data read at the threshold levels 81 to S4, and the gradation of the output of the hard copy recording is 5 levels according to the image on the display screen. It is reproduced in the same way.

However, when the level changes only between 60% and 80% as in the video signal (B) of FIG. 8, the number of read data becomes a value proportional to time T (time for one screen). Furthermore, since the difference in video signal level between threshold levels cannot be recognized, the entire screen of hard copy recording has the same gradation, resulting in a large difference in the image when compared with a monitor screen.

Also, when you particularly wanted to remove differences in images, you had to manually adjust the threshold level each time.

[Problem that the invention seeks to solve]

As mentioned above, in the conventional method of reading a video signal at a fixed threshold level, if there is a bias in the gradation change of the video signal as shown in Figure 8, the video signal is read between the threshold levels. Since the difference in signals cannot be recognized, the hard copy recording outputs the same gradation, resulting in a large difference in the image when compared with the monitor screen. In addition, the method of manually setting the threshold level was also notorious, but it took time to adjust and did not produce clean records.

[Means for solving problems]

In the present invention, in a hard copy device capable of recording M levels of gradation, a method of first checking the distribution of the video signal at N levels and then changing the settings to M levels is a method that is economically and economically viable. is also suitable. Therefore, this threshold level method is adopted in order to print out the video signal in accordance with the above-mentioned scale.

That is, in the present invention, as shown in the principle block diagram of FIG.
A video signal reading section 1 that reads the data at N threshold levels, and a counter 2 that counts the number of data for each of the N threshold levels are provided, and the threshold level with the larger number of data is determined according to the counted result. A data control unit 3 is provided that allocates M (M≧N) threshold levels at narrow intervals, and the output of this data control unit 3 automatically sets the reading threshold level for hard copy recording. The configuration is adopted.

[Effect]

A video signal reading section 1 first reads one screen worth of analog video signals at N threshold levels set at predetermined level intervals, and a counter 2 counts the number of data existing between each level. Corresponding to the result, the data control unit 3 allocates new threshold levels based on the data number ratio of each counter in order to allocate M threshold levels such that the threshold level interval is narrower for the one with the larger number of data. Calculate and output the threshold level. Furthermore, the video signal reading unit 1 is controlled by the output, and the second read video signal is stored in the screen memory 4, and the memory data is output as a hard copy record.

〔Example〕

FIG. 2 is a circuit diagram showing an embodiment of the present invention, and this circuit diagram shows a case where N=4 and M=12.

The comparators D1 to D4 of the threshold reading section 1 first have a fixed threshold level S1 (20χ
), 52 (40χ), S 3 (60%), 54 (
80χ) is input. Its output is V-3l, V-5
If the difference between V2, V-33 and V-34 is positive, the output will be logic "0", and if it is negative, the output will be logic "1'". This output is added to AI, A2, and A3 of counter 2, and the 1" data between each threshold level is counted using the video clock.
0%, 20-40%, 40-60%, 60-80%, 8
The number of video clocks in each time width between the threshold levels of 0% and 100% is counted as the number of data. Based on this data number, the data control unit 3 calculates a new reading threshold level based on the data number ratio, and outputs new threshold levels 81 to 512.

Next, these new threshold levels 81 to S12 are added to the threshold level reading section 1 to read the second and subsequent video signals, and the memories 1 to S12 of the respective screen memories 4 are read.
The data is stored in the memory 12 and the memory data is output as a hard copy record.

Figures 3 to 5 show the video signal (C) in the circuit diagram of Figure 2,
The relationship between threshold level and data number ratio is shown.

Figure 3 shows the video signal (C) for one screen, and Sl is 20χ
, S2 is 40χ, S3 is 60χ, and S4 is 80χ. The number of data is at times t1, t2, L3, ta, is
The values are proportional to each. The data number ratio in the exemplary video signal is 1:3:4:2:2. Figure 4 shows the relationship between the data number ratio counted by the counter and the video signal.
FIG. 5 shows the newly assigned threshold levels. In Figure 5, one line is between 0 and 20% level, and one line is between 20 and 20% level.
3 between 40% level, 4 between 40-60% level
Books, 2 books between levels 60-80%, 80%-100%
Two books are allocated between each level. A total of 12 assigned new threshold levels are used for reading and recording for hard copying.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, when an image is created on a display screen using an image creation system, there is a problem in that there is a large difference in gradation between the screen and the hard copy recording. The automatic threshold level setting method of the present invention solves this problem and is extremely effective in improving the quality of hard copy recording.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the principle configuration of the present invention, FIG. 2 is a circuit diagram showing an embodiment of the present invention, and FIG. 3 is a method for reading the first screen of a video signal (C) according to the present invention. FIG. 4 is a diagram showing the video signal (C) according to the present invention and the ratio of the number of data read. FIG. 5 is a diagram showing the video signal (C) according to the present invention and the second and subsequent reading methods. , Fig. 6 is a diagram showing the device configuration of the image creation system, Fig. 7 is a diagram showing a conventional method of reading the video signal (A), and Fig. 8 is a diagram showing the conventional method of reading the video signal (B). FIG. In Figure 1.2, 1 is a video signal reading section, 2 is a counter, 3 is a data control section, and the principle of the present invention is 9 zero 770-
/7 Figure 1 Senfu bullet Tqf hook σ so 9 spear T circuit Figure 2 Figure 3 Figure 4rJJ

Claims (1)

[Claims] A hard copy device with a gradation function that inputs an analog video signal and records an image on a display screen, wherein one screen of the video signal is divided into N images set at predetermined level intervals. A video signal reading unit (1) that reads the data at a threshold level, and a counter (2) that counts the number of data for each of the N threshold levels, and according to the counted result, select the one with the larger number of data. M (M≧N) that narrows the threshold level interval of
), the data control unit (
3), and the threshold level for reading a video signal for hard copy recording is set using the output of the data control unit (3).