JP3064946B2 - Video recording device with video confirmation function - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video recording apparatus adapted to an electronic still video or the like and having a function of confirming a video to be recorded before recording.

[0002]

2. Description of the Related Art Conventionally, there has been known an electronic still video camera in which a photographed image is displayed on a liquid crystal display section provided in a camera body (for example, Japanese Patent Application Laid-Open No.
-140543). It is also known that a captured image is displayed on a display unit, the display is confirmed, and if the display is OK, the image is recorded on a recording medium detachable from the camera body or a recording medium connected externally (for example, Kaisho 57
-44374).

[0003]

However, in the conventional video recording apparatus as described above, when confirming an image, there is a problem that if the display portion is small, the image, especially the image quality, cannot be confirmed sufficiently. For this purpose, it is conceivable to increase the size of the display unit, but this will increase the size of the camera.
The present invention has been made in order to solve the above-described problems, and has an image checking function that enables an arbitrary portion of an image to be enlarged and displayed so that the image can be sufficiently checked even if the display unit is small. It is an object of the present invention to provide a video recording device.

[0004]

According to one aspect of the present invention, there is provided an image pickup device, recording means for recording a video signal from the image pickup device on a recording medium, and an image from the image pickup device. Display means for displaying an image based on a signal; instructing means for instructing compression of a photographed image; and compression for performing a compression process on a video signal to be recorded in the recording means when the instructing means instructs compression. And a display control means for enlarging a part of the photographing screen based on the compressed video signal and displaying an enlarged image on the display means when compression is instructed by the instruction means. It is a video recording device. In this configuration, the video signal from the image sensor is recorded on the recording medium by the recording means, and an image based on the video signal is displayed on the display means. Then, when compression of the captured image is instructed by the instruction means, the compression means performs compression processing on the video signal to be recorded in the recording means, and the display control means displays a part of the photographic screen based on the compressed video signal. The image is enlarged and displayed on the display means. As described above, a part of the compressed image is enlarged and displayed in conjunction with the compression instruction, so that the state of the image quality of the image can be sufficiently checked. According to a second aspect of the present invention, in the configuration of the first aspect, the instruction means is configured to be capable of selecting a plurality of compression modes, and the display control means changes a display state according to the selected compression mode. It is to let. In this configuration, it is possible to select an arbitrary compression mode and check the degree of deterioration of the image quality at that time. According to a third aspect of the present invention, in the configuration of the first aspect, the display means has a finder function of displaying a video signal from an image sensor as a shooting screen. In this configuration, the display means functions not only to check the image quality but also as a normal finder for determining the composition at the time of shooting.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An outline of a still video system according to one embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 shows a configuration example of a still video camera using a solid-state memory. In FIG. 1, the imaging system includes an imaging lens 1, a mechanical shutter 2, an imaging device 3, and an aperture 4. When the shutter 2 is opened, a light beam passing through the imaging lens 1 forms an image on the imaging device 3. Image. At normal times other than the time of imaging, the light beam that has passed through the imaging lens 1 is guided to the finder optical system 6 by the mirror 5, and through this finder optical system 6, the photographer can check the subject and its framing.

The recording system includes an amplifier 7 for amplifying a video signal from the image sensor 3, an A / D converter 8 for converting the video signal from analog to digital, and a buffer memory for temporarily recording the A / D converted signal. 9, an image memory 10 as a recording medium, a digital operation circuit 11 for performing compression processing when recording a video signal, and a system controller 12 for performing overall control. In addition, a photometric element 13 for measuring subject brightness for exposure control is provided,
The photometric data from the element 13 is A / D converted by an A / D converter 14 and input to the system controller 12. Based on that, the system controller 12 controls the aperture 4. The system controller 12 is connected with a release switch SW1, a compression mode selection switch SW2 for appropriately selecting a mode from at least one or more compression modes (including a non-compression mode), and a function upgrade card 15. ing.

To explain the basic operation of the above configuration, when the photographer presses the release switch SW1, the system controller 12 A / D converts the amount of light obtained by the photometric element 13 by the A / D converter 14, and the system controller 1
2 performs an operation based on the value to determine the exposure value, thereby determining the value of the aperture 4, raising the mirror 5, determining the opening time of the shutter 2, and opening and closing the shutter 2. After the shutter 2 is closed, the image signal photoelectrically converted and stored in the image sensor 3 is transferred by a clock provided by a timing generator (not shown), amplified by an amplifier 7, and then digitally converted by an A / D converter 8. And stored in the buffer memory 9. The stored video signal is subjected to color separation processing, γ processing, white balance processing, and matrix processing in the digital operation circuit 11, converted into the form of Y, RY, and BY signals, and then subjected to compression processing. . The compressed signal is then written to an image memory 10 as a storage medium through a buffer memory 9. As the image memory 10, for example, a memory card or the like may be used.

In the above photographing operation, the photographer selects one mode from at least one or more compression ratios or compression methods by the compression mode selection switch SW2. The system controller 12 determines the compression ratio or compression method of the signal to be recorded based on the information of the switch SW2. Before the compressed signal is written from the buffer memory 9 to the image memory 10 as described above, a video image corresponding to the selected compression mode can be viewed on the finder optical system 6 (configuration for this purpose). Will be described in detail in FIG. 4 and thereafter.) The photographer confirms the deterioration due to compression with the viewfinder optical system 6,
By selecting a compression mode or a non-compression mode most suitable for the purpose of photographing, the image memory 1 with a satisfactory image quality is stored in the image memory 1.
Record to 0. It is convenient that the compression mode is set to a predetermined mode in an initial state. In particular, the optimal compression mode is set according to the capacity of the card and the function-up card (the card is selected by the photographer according to the photographing intention, and the shutter speed and aperture that are most suitable for the photographing intention are determined by the card information). It should just be.

FIGS. 2 to 3 show a method of compressing a video signal.
This will be described with reference to the drawings. The compression method is Y, RY, B
Each of the −Y signals is divided into, for example, a block of 16 × 16 pixels, and two-dimensional cosine transform coding (DCT) is performed in the block. Cosine transform coding
This is a method of compressing data using a transform called cosine transform. The cosine transform is one of orthogonal transforms represented by the Fourier transform and the Hadamard transform, and is said to be a transform method capable of performing encoding with the highest compression efficiency when using it. Assuming that the original image is f (i, j), the coefficient obtained by the conversion is F (u, v), and the number of pixels of the image is N × N, the two-dimensional cosine transform and the inverse transform are represented by the following equations.

[0010]

(Equation 1)

As shown in FIG. 2, the density information f (i, j) of the image is converted into spatial frequencies u, v by the cosine transform.
Is expanded to an amplitude value F (u, v) expressed by the following function. By performing the cosine transform, the properties of the data are converted into a more easily compressible form. It is known that the transform coefficient obtained by the cosine transform has the following properties. (A) The conversion coefficient is one DC component F (0,0) and 2
It consists of 55 (when N = 16) AC components F (u, v) (where u + v ≠ 0). As shown in FIG. 3 (a), among the AC components, An AC component closer to a DC component tends to have a larger coefficient value. That is,
Information necessary for constructing an image is relatively concentrated on the low frequency side. (B) As shown in FIG. 3 (b), the distribution of the conversion system numerical values of all the AC components of all the blocks is a Laplace distribution having a peak at zero. (C) The distribution of the conversion system numerical value of the AC component of each block can be approximated to a Laplace distribution having a peak at zero. The spread of the distribution varies from block to block. As the density of each pixel in the block changes more steeply, the spread of the distribution of the conversion coefficients increases, the average amplitude value of the coefficients increases, and the conversion coefficients of the high-frequency components also take larger values. (D) The distribution of conversion system numerical values of AC components having the same frequency in all blocks is a Laplace distribution having a peak at zero,
The spread of the distribution is greater for lower frequency components. As described above, the property of data having various density distributions for each image is led to a certain property that is not image-dependent (in this case, a property of a Laplace distribution having a peak at zero), thereby providing a statistical property. Compression using the technique becomes possible.

First, the image data is converted into a block image f (i, j) (i, j = 0,1,2,2) consisting of 16 × 16 pixels.
..., 15). Next, two-dimensional DCT is applied to the block image f (i, j) of 16 × 16 pixels, and a transform coefficient matrix F (u, v) (u, v = 0, 1, 2, 2,
..., 15). The conversion coefficient takes a real value. The way of quantization is changed according to the compression ratio selected by the compression mode selection switch SW2. That is, F (u, v) is all 8
If bits are given, no compression is achieved, but if the number of high-frequency bits is reduced according to the Laplace distribution described above, compression is achieved. The amount to be reduced is written in the ROM in advance, and data is read from the ROM according to the setting of the compression mode selection switch SW2. By performing this quantization, the image data is compressed. As described above, in the compression method according to the present embodiment, high-frequency components are mainly compressed, so that the compression reduces the high-frequency components.

FIG. 4 is a detailed view of the image pickup system shown in FIG.
A method for confirming the deterioration of the compressed video in this embodiment will be described with reference to FIG. As shown in the figure,
At least one spatial low-pass filter or light scattering filter is made freely insertable as an optical member 22 in the optical path of the finder optical system 6, and the system controller 12 drives the actuator 21 during compression to drive the spatial low-pass filter or light scattering filter. Is inserted into the viewfinder optical system 6 to display an image with a reduced high-frequency component or an image with a deteriorated S / N ratio. The photographer can confirm the deterioration of the compressed image by looking at this display. As the spatial low-pass filter, a filter using birefringence such as quartz, or a filter utilizing diffraction such as a phase-type low-pass filter can be adopted.

In order to select a compression ratio from a plurality of values, a plurality of spatial low-pass filters or light scattering filters may be freely inserted. For example,
If the compression ratio can be changed to three types, three low-pass filters can be inserted freely, and as the compression ratio increases, a low-pass filter with a lower cutoff frequency may be inserted. When the cutoff frequency is low and the high cutoff frequency is B, A + B,
What is necessary is just to insert like A and B.

In this embodiment, the spatial low-pass filter or the light scattering filter is inserted into the finder optical system, but may be inserted into the imaging lens 1. Also,
In the above embodiment, the optical viewfinder has been described as an example. However, when an electronic viewfinder (for example, a liquid crystal TV system) has a sufficient resolution, a spatial low-pass filter or a light scattering filter is inserted into the optical system of the electronic viewfinder. You may.

Next, another embodiment will be described. 4th
As the optical member 22 in the figure, an element having an electro-optic effect in which birefringence is varied by an electric field, for example, PLZT as shown in FIG. 5 is used. The function of the spatial low-pass filter is obtained by the action of the birefringence. In this case, the optical member 22 may be fixed. In this embodiment, by changing the voltage applied to the optical member 22 in accordance with the compression ratio and the compression method (that is, by changing the electric field), it is possible to change the birefringence and thereby change the action of the spatial low-pass filter.

Further, instead of the element having the electro-optic effect, an ultrasonic light polarization element using a change in the refractive index generated in the medium by the acousto-optic effect as the phase (diffraction) may be used. A function as a spatial low-pass filter is obtained by the action of this diffraction. By changing the frequency of the high-frequency sine wave signal applied to the ultrasonic light polarizing element, the angle of the diffracted light can be changed. Examples of such an element include fused quartz and As ₂ S ₂ . In this embodiment, by changing the frequency of the high-frequency signal applied to the optical member 22 in accordance with the compression ratio and the compression method, the diffraction angle can be changed, so that the action of the spatial low-pass filter can be changed.

In addition, an element having an electro-optical light scattering effect is used in place of the ultrasonic light polarization element, and the degree of scattering is changed by changing the applied voltage, whereby a spatial low-pass filter or an S
/ N deterioration filter. Examples of such an element include PLZT. By changing the voltage applied to the element according to the compression ratio and the compression method and changing the degree of scattering, the high frequency component is reduced, and the S / N
An image with a deteriorated ratio can be produced.

Further, as another embodiment, a plurality of images are formed by moving some elements of the imaging optical system or the finder optical system (for example, shaking at a frequency of 50 Hz or more), and a spatial low-pass filter is inserted. An equivalent state may be obtained. For example, as the optical member 22 in FIG. 4, a parallel flat plate made of transparent glass, plastic material or the like is used, and as shown in FIG.
1. It is configured to be able to oscillate by a small angle in the θ2 direction, and as shown in FIG. 7, the luminous flux is also oscillated by swaying the same plate by a small angle (in FIG. There). Thereby, a double image can be formed.

FIG. 8 shows the movement of the image when the above-mentioned plane parallel plate is shaken, and FIG. 9 shows the sequence of driving the plane parallel plate. In this example, the plane-parallel plate is driven so that the image moves between the positions "1" and "2" every 1/120 second. As a result, a function equivalent to a spatial low-pass filter without flicker can be obtained by using the afterimage of the human eye. In order to prevent flickering, the time during which the drive is in the "1" or "2" state must be shorter than 1/50 second. In addition, the characteristics of the spatial low-pass filter function can be changed by changing the amount of movement of the image. Therefore, by changing the amount of movement according to the compression ratio and the compression method, an image similar to the compressed image can be created.

In FIG. 8, a spatial low-pass filter is provided only in one direction. However, as shown in FIG. 10, the same plate is driven so that the image moves in the horizontal and vertical directions. It can function as a spatial low-pass filter in the horizontal and vertical directions. FIG. 11 shows a driving sequence of the parallel flat plate at that time. The horizontal and vertical drive sources may be independent. In this example, first, the parallel flat plate is swung in the θ1 direction (FIG. 6), whereby the image moves between the horizontal directions “1-2” in FIG. At this time, since the image does not move in the θ2 direction (FIG. 6), the image exists at the center “c” in the vertical direction. Next, by shaking in the θ2 direction, the image moves between “3-4” in the vertical direction. At this time, since the image does not move in the θ1 direction, the image is at the center “c” in the horizontal direction. In addition to the horizontal and vertical directions as described above, by shaking the plate so that the image moves in an oblique direction as shown in FIG. 12, a spatial low-pass filter effect can be provided in the oblique direction. Further, as shown in FIG. 13, a spatial low-pass filter effect can be provided by shaking the plate so that the image rotates.

In the above description, the method of moving the parallel plane plate as a method of moving an image has been described. However, an element whose refractive index changes is obliquely inserted into an imaging optical system or a finder optical system to change the refractive index. The image may be moved. In FIG. 4, the same effect can be obtained by swinging the mirror 5.

FIG. 14 shows still another embodiment. In this example, a part of the imaging optical system, in particular, the focusing lens 1
By moving f or a part of the finder optical system 6, a defocus state can be set. In this example, image quality deterioration is confirmed by changing the defocus amount according to the compression ratio and the compression method. It goes without saying that the imaging optical system is brought into a focused state during shooting.
As a configuration for driving the above-mentioned optical member, a configuration in which a normal focusing ring is rotated, or a configuration in which a focusing lens 1f is connected to a piezoelectric element 23 which is different from a normal focusing unit as shown in FIG. May be driven.

FIG. 15 is a block diagram of a still camera system according to still another embodiment. In this example, an electronic viewfinder (hereinafter abbreviated as EVF) 60 is used. Then, like a video camera, the signal from the image sensor 3 is converted to an A / D converter 8, a buffer memory 9,
The signal is processed through the / A converter 24 and the signal processing circuit 25 and is displayed on the EVF 60. Normally, EVF does not provide a sufficient number of pixels due to the demand for miniaturization, and therefore cannot be said to have a sufficient resolution. Therefore, even if the moving image state and the shooting screen are displayed on the EVF in accordance with the compression, it is not clear how the image quality changes due to the compression. Therefore, since the EVF generally emphasizes the high-frequency component by performing outline enhancement,
The image is displayed by changing the emphasis amount according to the compression ratio and the compression method. By looking at this display, the deterioration of the image quality can be confirmed.

FIG. 16 is a block diagram according to still another embodiment. In this example, an image according to a compression ratio and a compression method can be displayed on an electronic viewfinder (EVF) 60. By enlarging a part of a shooting screen,
The image quality can be checked for deterioration. The subject image is exposed to the image sensor 3 by pressing the release switch SW 1, and its optical signal is converted into an electric signal by the image sensor 3, A / D converted and stored in the buffer memory 9. This signal is further processed, compressed and stored in the image memory 10. In the present embodiment, the compressed signal is expanded, D / A converted, and the signal is processed.
Display on F60. It is to be noted that a display switch SW3 may be provided so as to display only when necessary,
A compression mode selection switch SW2 may be provided, and the display may be made by operating this switch.

The image displayed on the EVF 60 changes according to the selection of the compression mode selection switch SW2. E
After selecting the compression mode that has reached the photographing purpose while viewing the image on the VF 60, the system controller 12 presses the recording switch SW4 to cause the system controller 12 to operate the recording medium, that is, the image memory 10
Start writing video to. If the recording switch SW4 is not pressed, the recording may be performed in the selected compression mode when a certain time has elapsed after the release operation or the switching operation of the compression mode selection switch SW2, or conversely, the recording may be canceled. May be performed. The recording switch SW4 is also used as a release button of the release switch SW1, and may be configured to record on a recording medium when the release operation is performed again.

Normally, the number of pixels of the EVF is not enough compared with the video information to be recorded. Therefore, a part of the photographing range is enlarged and displayed on the EVF, so that the EVF has a sufficient display compared to the video information to be recorded. The display according to the compressed signal enables the deterioration of the image quality to be clearly confirmed. Also, by changing the signal processing in a digital or analog signal processing circuit in accordance with the compression ratio or the compression method, the characteristics of the electric low-pass filter can be changed.
A process for lowering the / N ratio may be performed.

FIG. 17A shows a method for enlarging a part of the photographing range (framing) displayed by the EVF.
(B) As shown in (c), the magnification is variable (for example,
I, II), or as shown in FIG. 18, the enlargement location may be selected from a plurality of locations (for example, A to E), which makes it easy to confirm image quality deterioration. Further, as shown in FIG. 19, a position in the viewfinder where a part of the photographing range, for example, the center portion is enlarged and displayed may be selectable. In this example, the positions A to D can be selected, and the position B is enlarged in the drawing.

[0029]

As described above, according to the first aspect of the present invention,
When a video signal from an image sensor is subjected to a compression process and recorded on a recording medium, a part of an image based on the compressed video signal is enlarged and displayed on a display unit in conjunction with the image compression instruction. As a result, the image quality state of the image compressed and recorded on the recording medium can be understood well, and the image quality of the image can be sufficiently confirmed even with a small display means,
Image recording with an appropriate compression process can be performed. Also,
According to the second aspect of the present invention, in addition to the above effects, the compression mode can be arbitrarily selected, so that the degree of compression of the image can be appropriately set after confirming the degree of deterioration of the image quality. According to the third aspect of the present invention, in addition to the above-described effects, the display means can be used not only for checking the image quality but also as a normal finder for determining the composition at the time of shooting.

[Brief description of the drawings]

FIG. 1 is a block diagram of a still video system according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating cosine transform as one method of compression.

FIGS. 3A and 3B are a distribution diagram of transform coefficients obtained by cosine transform and a histogram of the coefficients.

FIG. 4 is a detailed view of an image pickup system of the steal video system.

FIG. 5 is a side view showing an example of an optical member used to confirm deterioration of an image due to compression.

FIG. 6 is a perspective view of a parallel plane plate as another example of the optical member.

FIG. 7 is a diagram showing movement of a light beam when the plate is driven.

FIG. 8 is a diagram showing the movement of an image in the above.

FIG. 9 is a diagram showing the above-described driving procedure.

FIG. 10 is a diagram illustrating another example of image movement.

FIG. 11 is a diagram showing another driving procedure.

FIG. 12 is a diagram illustrating movement of an image.

FIG. 13 is a diagram illustrating movement of an image.

FIG. 14 is a detailed diagram showing another example of the imaging system.

FIG. 15 is a block diagram showing another embodiment of the still video system.

FIG. 16 is a view showing still another embodiment.

17 (a), (b) and (c) are views showing an electronic view finder capable of enlarging and changing a part of a photographing range.

FIG. 18 is a diagram illustrating an electronic viewfinder in which an enlargement position can be selected.

FIG. 19 is a diagram illustrating an electronic viewfinder in which an enlarged display position is variable.

[Explanation of symbols]

 Reference Signs List 3 image pickup device 60 electronic viewfinder (display means) 10 image memory (recording medium) 11 digital operation circuit (compression means, display control means)

Claims (3)

(57) [Claims] An image pickup device and recording for recording a video signal from the image pickup device on a recording medium.
Means for displaying an image based on a video signal from the image sensor
Display means, instructing means for instructing compression of the photographed image, and when the instructing means instructs compression, the recording is performed.
Means for compressing the video signal to be recorded in the means
And when compression is instructed by the instruction means,
Enlarge part of the shooting screen based on the video signal
A video recording device having a video confirmation function, characterized in that the video recording device is provided with a display control means for enlarging the display . 2. The instruction means selects a plurality of compression modes.
And the display control means is configured to select the selected compression mode.
The video recording device having a video confirmation function according to claim 1, wherein a display state is changed according to a mode . 3. The video recording apparatus according to claim 1, wherein said display means has a finder function of displaying a video signal from an image sensor as a photographing screen.