JPH011921A - Photometric object tracking device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to a photometric object tracking device disposed in a photographing device such as a video camera or a silver halide camera.

(Background of the Invention) Conventionally, as a method that enables photometry according to the photographer's will, a multi-point evaluation photometry method is used. There is a method that stores the value and calculates the photometric value by calculation based on this multi-value. However, since the memorized value of each point in this method is a past value, it is difficult to predict subsequent changes in the photometric value or the photometric target (main This method was difficult to use when the subject (object) moved or when controlling auxiliary light.

Additionally, there are already computers that allow you to specify arbitrary points externally using an When applied to equipment, there was a problem that the framing would change depending on the operation, and it could not be applied easily.

(Object of the Invention) An object of the present invention is to provide a photometry object tracking device that allows a photometry device to perform photometry corresponding to a certain degree of positional change of the main subject within the screen, and allows the photographer to concentrate on framing. It is to be.

(Features of the Invention) In order to achieve the above object, the present invention provides a photometric area initial position specifying means for specifying an initial photometric area at the center of the screen, and a photometric area initial position specifying means that specifies an initial photometric area at the center of the screen. Detection means for detecting a tendency of subsequent changes in brightness distribution within the set photometry area, and detection of the position of the photometry area set at the center of the screen by the photometry area initial position designation means using the first stage of the detector. and a photometric area position variable means for moving the photometric area according to the result, so that the photometric area is automatically tracked by the main subject, assuming a change in the position of the main subject in the screen based on the tendency of the brightness distribution change. It is characterized by the following.

(Embodiment of the Invention) FIG. 1 is a block diagram showing an embodiment of the invention, and shows a case where the invention is applied to a video camera.

1 is a photographing lens, 2 is a two-dimensional image sensor consisting of a CCD, etc., 3 is a memory circuit for storing video signals, 4 is a subject image display, and the center of the screen when the measurement set signal currently performing photometry is input. 6 is the address signal generating circuit 5, which generates an XY address signal indicating the initial photometric area position, and thereafter generates an address signal indicating the photometric area position based on a signal from a detector, which will be described later.
7 is a selection circuit to which an address signal is input, and a selection circuit 7 determines the brightness of the main subject from the sent video signal, and the reflected light from the side wave subject passes through the photographing lens l and displays the subject image on the two-dimensional image sensor 2. The image is then converted into a video signal.

This video signal is stored in the storage circuit 3 and is also sent to the display 4, where the image of the subject is displayed. The photographer performs framing while viewing the subject image displayed on the display 4.

Further, the video signal output from the image sensor 2 is also input to the selection circuit 5, and here, for example, the entire screen including the surrounding area is selected for the photometry area according to the address signal from the address signal generation circuit 5. An operation is performed to extract a video signal of a small area of about 1/16 of the size from the video signal of the entire screen from the image pickup device 2. Furthermore, since the address signal is also input to the display 4, the position of the photometry area at this time is displayed on the display 4, and the photographer can check the current area on the screen by looking at this display. The movement of the main subject is detected by checking trends in color or brightness information from the ever-changing video signal. For example, if the brightness pattern is as shown in Figure 2 (a), but the left side tends to be brighter and each of them becomes brighter as shown in Figure 2 (b), the main subject will be on the right side. It is determined that the hair trace has shifted to the left (or the camera has shifted to the left), and an instruction signal is sent to the a (res signal generation circuit 5) to change the hair trace in the direction where the brightness pattern is most similar within the small area, that is, in this case, to the right. The address signal generating circuit 5 receives this signal and changes the XY address position.

By repeating the above operations, the photometry area that was in the center of the screen at the time of reset can be subsequently tracked within the screen according to the main subject, and the photometry area can be indicated on the display 4. Become. Therefore, the brightness of the main subject can be appropriately measured by the measurement circuit 7 even if the main subject moves to some extent as described above.

In the above explanation, we have described the case where the brightness distribution within the small area has a single tendency, but even if the overall brightness pattern changes as shown in Figure 2(c), the address will not change. In other words, the address is changed only depending on the trend of the brightness information, and thus a system in which only the photometric value corresponds to changes in overall brightness can be realized.

The above does not necessarily apply to r300X, like a video camera.
300. , l pixels, it is possible to use a two-dimensional image sensor consisting of pixels of rl 00x 100J, r50x50'', and even in a silver halide camera, the degree of freedom of the viewfinder can be improved. It is possible to arrange a two-dimensional image sensor having pixels of about rt00xloOJ for framing in order to increase the number of pixels, and it goes without saying that the same effect can be obtained in this case as well.

FIGS. 3 and 4 show other embodiments of the present invention. In the embodiment described above, the position of the photometry area for photometry was set by inputting XY address signals, but in this embodiment, the position of the photometry area is set mechanically.

In FIG. 3, 9 is a camera box, 10 is a strobe unit, and 11 is a photographic lens. Light passing through the photographic lens 11 is incident on a film surface 12 via a shutter (not shown). Reference numeral 13 denotes an objective lens, and the photographer observes an image formed once by the objective lens 13 and the eyepiece lens 14. Reference numeral 15 denotes a substantially transparent sensor substrate placed near the image forming plane and movable vertically and horizontally, in the center of which a group of photoelectric conversion elements made of amorphous silicon, for example, a sensor 15a is arranged in a small area. sensor 1
5a itself also serves as a mark indicating the photometric area position. 1
Reference numeral 6 denotes a spring, and the sensor board 15 is held by the spring 16 and electromagnetic drive coils 17 and 18 so as to be movable up and down and left and right.

FIG. 4 is a block diagram of this embodiment, and the operation will be explained using this diagram.

The photoelectric output of the small area from the sensor 15a is the gate circuit 1.
9 is output to the memory circuit 20 and stored in the memory circuit 20. At the same time, it is also output to the comparison circuit 21,
The comparison circuit 21 compares the stored value from the storage circuit 20 with the signal directly sent from the sensor 15a, and outputs the result to the division circuits 23 and 24. The values stored in the storage circuit 20 are output to the comparison circuit 21 as described above, and are also output to the trend detector 22, where the tendency of the stored values (for example, the tendency that the right side is bright) is detected. It is output to the division circuits 23 and 24. As a result, the division circuit 23.2
4 detects changes in the luminance pattern in the vertical and horizontal directions, and supplies this detection signal to drive circuits 26 and 27 via the gate circuit 25. Then, the electromagnetic drive coils 17, 18 are activated by the action of the drive circuits 26, 27, and the sensor board 15, that is, the sensor 15a itself, tracks the main subject, making it possible to perform appropriate photometry on the main subject.

The tracking step time is determined by the cycle of pulses output from the oscillation circuit 28, that is, the OR gate 29
is determined by the pulse output applied to the gate circuit 19 via the OR gate 3, and when the gate circuit 19 is open and the photoelectric output is stored in the storage circuit 20, the OR gate 3
Since the inverted signal is input to the gate 25 through 0, the gate circuit 25 closes the gate, and during this time the drive circuit 26
．． No detection signal is given to sensor 27, and the position of sensor 15a does not change. Since this interval can be made quite fast, it is possible to track relatively fast changes in framing. It goes without saying that tracking may be carried out using heat theory or well-known correlation detection.

The central position of the sensor 15a can be set by operating the set switch 31. That is, when the set switch 31 is operated, it is not only memorized by the flip-flop 32, but also applied to the gate circuit 34 via the OR gate 33, so that the gate 34 opens and the median value is The output circuit 35 outputs XY address signals to the drive circuits 26 and 27, and the sensor 15a is set at a position according to the signal, that is, at the center of the screen.

After this, the tracking operation as described above is automatically performed. Note that at this time, since the gate of the gate circuit 25 is closed via the OR gates 29 and 30, the division circuit 23
．． The tracking control based on the detection signal from 24 is stopped at -.

Next, we will discuss the time of shooting. When the switch 36 is operated, the gates of the gate circuits 37 and 38 are opened, and the sensor is located at a location corresponding to the main subject, which was initially set at the center but has since been moved by tracking control. The photoelectric output from 15a is transmitted to the gate circuit 37.
．． 38, it is output to an exposure control circuit and a dimming control circuit (not shown). As a result, exposure control suitable for the main subject is performed. At this time, the OR gate 30 works to cut off the tracking system in order to prevent the tracking system from working when the switch 36 is released. Further, the AND gate 39 has the function of automatically setting the sensor 15a at the center when the release operation is performed using the switch 36 without setting the sensor 15a at the center due to the operation of the set switch 31. That is, when the switch 36 is operated, the output of the AND gate 39 becomes high level, so the gate circuit 34 opens the gate via the OR gate 33, and the median output circuit 35 opens.
address signals are applied via the drive circuits 26 and 27, and the sensor 15a will be located at the center. Although not directly related to the present invention, by moving the distance measurement system in conjunction with the sensor 15a, distance measurement suitable for the main subject becomes possible.

According to this embodiment, the trend of color or brightness within a small area (
Assuming a certain degree of positional change of the main subject within the plane due to changes in brightness pattern (brightness pattern), the camera automatically tracks the main subject using the metering area that was initially set at the center of the screen. Even with a handheld device such as the 1000, it is possible to perform light metering that corresponds to a certain degree of movement of the main subject within the screen without being affected by changes in the overall brightness of the screen, making it possible to set the appropriate exposure for the main subject. It becomes possible to give. In addition, this makes it possible to control light to points outside the center without pre-flashing, allowing correct light control even with strobes and multiple flashes with poor light distribution, and even under backlight that changes depending on the comparison with the center. , it is possible to adjust the light to match the backlit main subject and background.

(Effects of the Invention) As described above, according to the present invention, there is provided a photometric area initial position specifying means for specifying an initial photometric area in the center of the screen, and a photometric area initial position specifying means that specifies an initial photometric area in the center of the screen. a detection means for detecting a tendency of subsequent changes in brightness distribution within the set photometry area; and a detection means for determining the position of the photometry area set at the center of the screen by the photometry area initial position designation means, based on the detection result of the detection means. and a photometric area position variable means for moving the photometric area according to the change in the brightness distribution, so that the main subject automatically tracks the photometric area by assuming a change in the position of the main subject in the screen based on the tendency of the luminance distribution change. By using the same operations as storing conventional spot metering, it is possible to have the metering device perform metering (not memorized) at the time of shooting that corresponds to a certain degree of change in the position of the main subject within the screen, and it also allows the photographer to frame the photo. Get focused.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 (
a) (b) (c) are diagrams to help explain the operation of the illustrated detector in FIG. 1, and FIG. 3 is a diagram showing another embodiment of the present invention.
FIG. 4 is a block diagram of the camera. 2...Image sensor, 4...Display device, 5.
... Address signal generation circuit, 6 ... Selection circuit, 8 ... Detector, 15a ... Sensor, 19 ... Gate circuit, 20 ...Memory circuit, 21...Comparison circuit, 22...
Trend detector, 23.24... Division circuit, 25.
...Gate circuit, 26.27...Drive circuit. Patent applicant Canon Co., Ltd.

Claims (1)

[Claims] (1) A photometric area initial position specifying means for specifying an initial photometric area at the center of the screen, and a subsequent tendency of luminance distribution changes within the photometric area set at the center of the screen by the photometric area initial position specifying means. and a photometry area position variable means for moving the position of the photometry area set at the center of the screen by the photometry area initial position designation means in accordance with the detection result by the detection means. Target tracking device.