JPS6250033B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for measuring the amount of deviation of the center position of an image.

Until now, in order to measure the amount of deviation in the center position of an image, a V-shaped pattern with right-angled vertices as shown in Figure 1 was imaged, the phases of video signals of different color channels were compared, and both V-shaped patterns were imaged. The phase difference of the video signal for one scanning line across the character is calculated and the horizontal positional deviation amount △H = A + B/2 and the vertical positional deviation amount △V = A-B/2 are calculated. be. This method is described in Japanese Patent Publication No. 53-39287 and will not be described in detail here, but this method has the disadvantage of requiring a special pattern for measurement.

In order to solve this drawback, the present invention makes it possible to measure the amount of center position shift of an image by capturing an image of an achromatic object or a general object with a clear outline.

In order to measure the amount of center position shift of an image without using a special pattern, the present invention captures an image of a general achromatic subject or a subject with a clear outline, extracts a square from the center of the screen, and creates a square between the image and the square. This method measures the amount of center position deviation based on geometric relationships.

FIG. 2 shows an image capture screen and waveforms corresponding to an embodiment of the horizontal center position deviation measuring device of the present invention. An achromatic, vertical object with a clear outline is imaged, and the object is placed approximately in the center of a reproduction screen 1. Furthermore, a signal obtained by superimposing a green video signal 2 and a red or blue video signal 3 is displayed on the reproduction screen 1. Next, the central part of this image is electrically extracted into a square shape, and the video signal 2 of this part of the green channel, which serves as a reference, is input to the differentiator 4. The video signal 3 of the red or blue channel passes through the delay device 5, is delayed by more than the maximum adjustment range, and is input to the differentiator 6. Here, the delay device 5 is provided so as to provide a predetermined phase difference when the phases of each color channel match, in order to simplify processing by a phase pulse generator 7, which will be described later. Next, these two differential pulses are transferred to a phase pulse generator 7.
Here, a pulse with a pulse width equal to the phase difference between the two differential pulses is generated, and the AND gate 8
Accordingly, the timing pulse from the oscillator 9 is input to the counter 10 for a period of time corresponding to this pulse width. The result is converted into a voltage signal using the scale converter 11 to detect the amount of horizontal positional deviation, and the display device 1
Display on 2.

FIG. 3 shows an image capturing screen corresponding to an embodiment of the vertical center position deviation measuring device of the present invention. In this case, first measure the horizontal shift using the method shown in FIG. 2, and then take an image of an achromatic, tilted object with a clear outline, so that it is positioned approximately in the center of the screen 1. Then, by a sampling pulse for extracting the video signal in a square at the center of the screen 1, the red or blue video signal 3 within the square is processed by the AND gate 13.
is sampled and the corresponding number of scan lines (the number of scan lines included while the signal 3 traverses vertically opposite sides of the square sampling pulse) is calculated by the scan line count circuit 14. Let this value be a. Next, the horizontal phase difference between the red or blue video signal 3 and the green video signal 2 is calculated using the AND gate 15 and the horizontal center position deviation measuring circuit 16 shown in FIG. Let this value be n. Arithmetic circuit 17
Now count the number of scanning lines a corresponding to the vertical phase difference obtained above, the count number n corresponding to the horizontal phase difference, and the length of one side of the square as a known number using the counter 10 in Figure 2. The vertical positional deviation amount ΔV is calculated as an amount converted into time from the number N of scan lines, the number A of scanning lines corresponding to the length of one side of the square, and the time x corresponding to the count number N.

First, since the time per count in the horizontal direction is x/N, if the above n is expressed in time, it becomes n*x/N.

Also, since the number of scanning lines A is equivalent to the length of one side of a square, the time per one scanning line in the vertical direction is x/A when converted to the time in the horizontal direction, and if the above a is expressed in time, It becomes a・x/A.

Here, as is clear from the image capture screen of FIG. 3, the triangle surrounded by video signal 3, a and N, and the triangle surrounded by video signal 3, ΔV and n are similar.

Therefore, the following calculation formula holds true.

△V:a・x/A=n・x/N:x △V=x/N・a/A・n (sec) This calculation result is converted into a voltage signal by the scale converter 18 to calculate the vertical position shift. Determine the amount and display device 1
Display on 9.

As explained above, according to the present invention, any object that is achromatic and has a clear outline can be used to measure the amount of center position deviation of the image without imaging a special pattern. It's convenient. Furthermore, since the measuring method of the present invention converts vertical deviation into horizontal time, the measurement accuracy is approximately the same in both horizontal and vertical directions.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the principle of measuring the center position deviation amount using a conventional special pattern, and Fig. 2 is a block diagram and an image capturing screen of an embodiment of the horizontal direction deviation measurement device of the present invention. , FIG. 3 is a block diagram and an image capturing screen of an embodiment of the vertical deviation amount measuring device of the present invention. 4, 6: Differentiator, 7: Phase pulse generator, 1
0: Counter, 14: Scanning line number counting circuit, 1
6: Horizontal direction deviation measuring circuit, 17: Arithmetic circuit.

Claims (1)

[Claims] 1. A circuit that images a vertical object and extracts a square portion corresponding to the center of the imaged screen from each color channel video signal obtained, a circuit that differentiates the extracted each color channel video signal, and a circuit that differentiates the extracted color channel video signal. A circuit that detects the phase difference between the differential waveform signals, a circuit that generates a pulse only within the time of the phase difference, a circuit that counts the number of generated pulses, and a circuit that outputs the counting result to each color channel video signal in the horizontal direction. A horizontal positional deviation measuring device consists of a circuit that displays the amount of positional deviation between Sometimes, a circuit detects the point at which the tilted subject image crosses opposite sides of the square and counts the vertical difference between the two points in terms of the number of horizontal scanning lines, and A circuit that measures the horizontal deviation between video signals, a circuit that performs predetermined calculations on each data obtained as described above, and a circuit that displays the results as the amount of positional deviation between the video signals of each color channel in the vertical direction. What is claimed is: 1. A device for measuring an amount of center position deviation of an image, comprising: a vertical direction position deviation amount measuring device.