JP4100905B2 - Imaging apparatus, control method thereof, control program, and recording medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention forms a scene image on an image sensor such as a CCD, converts the scene image into an electrical image signal with this image sensor, and allows a photographer to observe the scene. The present invention relates to an imaging apparatus having a so-called EVF function for displaying an image on a display such as a liquid crystal, a control method thereof, a control program, and a recording medium.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, electronic still cameras and video cameras that electrically record a photographic field image on a recording medium have been proposed and commercialized.
[0003]
In these cameras, a photographic field image is formed on an image sensor such as a CCD by a photographic lens, and the scene image is converted into an image signal by the image sensor and recorded on a recording medium such as a video tape or a flash memory. To be recorded. There is also a camera having a so-called electronic view finder that displays an object scene image converted into an image signal on a screen such as a liquid crystal display to display a finder. In these cameras, the display resolution in the operation of the electronic viewfinder is always fixed.
[0004]
[Problems to be solved by the invention]
However, the conventional cameras as described above have the following problems because the display resolution is fixed.
[0005]
In order to realize a high-resolution finder operation, data acquisition processing and image digital processing must be performed at high speed, and hardware with high performance is required. Therefore, when operating with hardware that does not have a very high performance, processing is not in time, resulting in awkward video with a low frame rate. In this case, for example, even when shooting a scene with intense movement such as a sports scene, there is a problem that it is difficult to determine the composition because the finder cannot follow the movement of the scene.
[0006]
If the absolute processing amount is reduced by lowering the finder resolution, the color reproducibility and pixel density will deteriorate and the image quality will deteriorate, so it will be visible on the finder when shooting beautiful scenery. There is a problem that the image and the captured image are separated from each other.
[0007]
In order to solve this problem, Japanese Patent Application Laid-Open No. 11-313230 includes selection means for changing the resolution of an image displayed on the electronic viewfinder, and monitors the captured image on the electronic viewfinder at the selected resolution. Proposals have been made to display.
[0008]
However, in the above-described conventional example, it is necessary for the photographer himself to determine the resolution change according to the photographing scene and to input it to the camera, which is troublesome for the photographer.
[0009]
Accordingly, the present invention has been made in view of the above-described problems, and an object of the present invention is to provide an imaging apparatus capable of performing appropriate finder display corresponding to the degree of movement of the subject, a control method thereof, a control program, and a recording. To provide a medium.
[0010]
[Means for Solving the Problems]
In order to solve the above-described problems and achieve the object, an imaging apparatus according to the present invention includes an imaging unit having an imaging element that converts an object scene image formed by a photographing lens into an object scene image signal; A display means for monitoring and displaying a scene image signal obtained from the imaging means as a scene image, and two scene image signals successively converted by the imaging device are compared, and the scene image A scene image motion determining means for determining whether or not the scene image is a dynamic scene image based on the size of the area of the portion of the signal that has moved; And control means for changing the frame rate of the object scene image displayed on the display means in accordance with the judgment result of the field image motion judgment means.
[0011]
Further, in the imaging apparatus according to the present invention, the control means responds to the fact that the object scene image movement determining means determines that the object scene image is a dynamic object scene image. It is characterized by increasing the rate.
[0012]
In the imaging apparatus according to the present invention, the control means changes the resolution of the object scene image displayed on the display means together with the change of the frame rate.
[0013]
Further, in the imaging apparatus according to the present invention, the control means has a plurality of combinations of resolutions and frame rates for displaying the object scene image on the display means, and the determination of the object scene image motion determination means According to the result, one of the plurality of combinations of resolution and frame rate is determined.
[0015]
The image pickup apparatus control method according to the present invention includes an image pickup unit having an image pickup element that converts a field image formed by a photographing lens into a field image signal, and a field obtained from the image pickup unit. An image pickup apparatus control method comprising: a display means for displaying an image signal as a field image on a monitor, comparing two field image signals successively converted by the image pickup device; It is determined whether the object scene image is a dynamic object scene image based on the size of the area of the portion of the field image signal that has moved , and the display is performed according to the determination result. The frame rate of the object scene image displayed on the means is changed.
[0016]
In the image pickup apparatus control method according to the present invention, the frame rate is increased in response to determining that the object scene image is a dynamic object scene image.
[0017]
In the imaging apparatus control method according to the present invention, the resolution of the object scene image displayed on the display means is changed together with the change of the frame rate.
[0018]
Further, in the control method of the imaging apparatus according to the present invention, a plurality of combinations of resolutions and frame rates for displaying the scene image on the display means are prepared, and the scene image is a dynamic scene image. One of the combinations of the plurality of resolutions and frame rates is determined in accordance with the determination result of whether or not.
[0020]
A control program according to the present invention causes a computer to execute the above control method.
[0021]
A recording medium according to the present invention is characterized in that the control program is recorded.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.
[0023]
FIG. 1 is a block diagram showing a schematic configuration of a digital camera according to an embodiment of the present invention.
[0024]
In FIG. 1, reference numeral 101 denotes a CPU (Central Processing Unit), and the operation of the digital camera is controlled by the CPU 101. In order to supply power to the CPU 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, a data storage unit 104, an image processing unit 108, an LCD control unit 111, a shutter SW 114, which store control programs. The DC / DC converter 117 is connected to each other, and a CCD control unit 107 and a CCD 106 are connected to the image processing unit 108. The CCD 106 has about 4.92 million effective pixels (2560 × 1920). The object scene image is formed on the CCD 106 by the lens group 105.
[0025]
The LCD control unit 111 is connected to a display drive unit 112 and a display unit (TFT color liquid crystal) 113, and the DC / DC converter 117 is supplied with power from a battery 116.
[0026]
The CPU 101 performs various controls based on a control program in the ROM 102. Among these controls are processing for reading a captured image signal output from the image processing unit 108 and performing DMA transfer to the RAM 103, similarly processing for performing DMA transfer of data from the RAM 103 to the LCD control unit 111, and image data Is stored in the data storage unit 104 in a file format after JPEG compression.
[0027]
Further, the CPU 101 issues an instruction to change the finder resolution in accordance with an object scene image movement determination algorithm for determining whether or not the position of the object scene image has changed greatly based on the photographed image signal. 107, the image processing unit 108, the LCD control unit 111, and the like are instructed to change the number of pixels for data capture and digital image processing.
[0028]
In addition, processing for outputting a control signal for controlling the supply of power to each unit to the DC / DC converter 117 is also based on the control of the CPU 101. Has been done.
[0029]
The RAM 103 includes an image development area 103a, a work area 103b, a VRAM 103c, and a temporary save area 103d. The image development area 103a is a temporary buffer for temporarily storing the captured image (YUV digital signal) sent from the image processing unit 108 and the JPEG compressed image data read from the data storage unit 104. Used as an image-dedicated work area for image compression processing and decompression processing.
[0030]
The work area 103b is a work area for various programs. The VRAM 103 c is used as a VRAM that stores display data to be displayed on the display unit 113. The temporary save area 103d is an area for temporarily saving various data.
[0031]
The data storage unit 104 is a flash memory for storing captured image data JPEG-compressed by the CPU 101 or various attached data referenced by an application in a file format.
[0032]
The lens group 105 includes a plurality of lenses for optically projecting the object scene image onto the CCD 105, and the CCD (photoelectric conversion element) 106 converts the captured image projected by the lens group 105 into an analog electrical signal. It is an element for conversion.
[0033]
The CCD 106 can output thinned pixel data in the horizontal and vertical directions in accordance with a resolution conversion instruction from the CPU 101. The CCD control unit 107 is a timing generator for supplying a transfer clock signal and a shutter signal to the CCD 106, a circuit for performing noise removal and gain processing of the CCD output signal, and for converting an analog signal into a 10-bit digital signal. A / D conversion circuit, and similarly, a circuit for performing pixel thinning processing in accordance with a resolution conversion instruction from the CPU 101, and the like.
[0034]
Further, the image processing unit 108 performs image processing such as gamma conversion, color space conversion, white balance, AE, and flash correction on the 10-bit digital signal output from the CCD control unit 107, and YUV (4: 2: 2) An 8-bit digital signal is output in the format. These processing systems can also perform processing corresponding to an arbitrary resolution in accordance with a resolution conversion instruction from the CPU 101. These lens group 105, CCD 106, CCD control unit 107, and image processing unit 108 are collectively referred to as a camera module hereinafter.
[0035]
The LCD control unit 111 receives the YUV digital image data transferred from the image processing unit 108 or the YUV digital image data obtained by performing JPEG decompression on the image file in the data storage unit 104, and converts it into an RGB digital signal. After that, a process of outputting to the display driving unit 112 is performed. The display driving unit 112 performs control for driving the display unit 113, and also supports an arbitrary resolution in accordance with a resolution conversion instruction from the CPU 101. The display unit 113 is a VGA standard (640 × 480 dot) TFT liquid crystal display device for displaying an image, and a photographer views an object scene image displayed on the display unit 113 through an eyepiece lens (not shown). It is an electronic viewfinder (hereinafter referred to as EVF) that can determine the composition of the camera.
[0036]
The LCD control unit 111, the display driving unit 112, and the display unit 113 constitute display means.
[0037]
It should be noted that 1/64 (horizontal 1/8 × vertical 1/8) thinning mode in which image information of effective pixels 2560 × 1920 of the CCD 106 is thinned out to 320 × 240 pixels, and thinned out to 640 × 480 pixels are captured 1 There is a / 16 (horizontal 1/4 x vertical 1/4) thinning mode. Images captured in the 1/64 thinning mode are updated at 60 frames per second (so-called frame rate). The image is displayed on the EVF in the same 30 frames.
[0038]
The shutter SW 114 is a shutter for instructing the start of the photographing operation. The shutter SW 114 has a two-step switch position depending on the pressing pressure of the switch. When the first-stage position (SW1ON) is detected, camera settings such as white balance and AE are locked, and the second-stage position ( Upon detection of (SW2ON), an operation for capturing the object scene image signal is performed.
[0039]
The battery 116 is a rechargeable secondary battery or a dry battery. Further, the DC / DC converter 117 receives a power supply from the battery 116, generates a plurality of power supplies by performing boosting and regulation, and supplies a power supply of a necessary voltage to each element including the CPU 101. The DC / DC converter 117 can control the start and stop of each voltage supply by a control signal 118 from the CPU 101.
[0040]
FIG. 2 is a flowchart showing a flow of the EVF (electronic viewfinder) function in the camera photographing operation mode, and is a process performed in accordance with an instruction from the CPU 101 by a program stored in the ROM 102.
[0041]
In step S200, when the power is turned on, first, in step S201, a counter indicating the number of times of image capture from the EVF CCD 106 is set to an initial value n = 1, and a bit is set so as to execute the 1/64 thinning mode. Can be stood. In step S202, the CCD module including the CCD 106 and the CCD control unit 107 is set in an operable state (enable).
[0042]
In step S203, it is determined whether or not a 1/64 thinning mode flag is set. If the flag is set, 1/64 thinning mode control for outputting 320 × 240 pixel size data in step S204. Are performed after step S206.
[0043]
On the other hand, if the 1/64 decimation mode flag is not set and the 1/16 decimation mode flag is set in step S203, the process branches to step S205. A process for displaying an image with a size of × 480 pixels is executed.
[0044]
In step S206, in the determined 1/64 or 1/16 thinning mode, the optical information of the object scene captured from the camera lens group 105 is converted into an electric signal by the CCD 106.
[0045]
In step S207, the signal captured in step S206 is A / D converted into a 10-bit digital signal through noise removal processing and gain processing by the CCD control unit 107, and then sent to the image processing unit. The A / D converted image is also written in the RAM 103 as a frame memory for comparison with the next image, as will be described later.
[0046]
In step S208, it is determined how many times the currently captured image has been turned on, and if it is the first time, the process branches directly to step S213 to perform image display processing.
[0047]
On the other hand, in the case of the second time or later, the process proceeds to step S209.
[0048]
Steps S209 and S210 constitute a scene image motion determination unit that determines whether or not the scene image is a dynamic scene image, the details of which will be described later.
[0049]
In step S209, the magnitude of the motion of the object scene is quantified based on the comparison between the previous image signal stored in the RAM and the image signal captured this time, and in step S210, the subject motion is detected based on the result of step S209. It is determined whether the scene image is a dynamic scene with intense motion or a static scene with little motion. If it is determined that the scene is a dynamic scene, 1/64 decimation is performed in step S211. After setting a flag so that the next image capture is performed in the mode, the process proceeds to step S213 and subsequent steps which are image signal processing.
[0050]
On the other hand, if it is determined that the scene is static, a flag is set so that the next image capture is performed in the 1/16 decimation mode, and the process proceeds to signal processing in step S213.
[0051]
In step S213, the image processing unit 108 performs processing such as auto white balance, AE, and correction during strobe shooting of the currently captured image, or processing such as signal conversion to the YUV (4: 2: 2) format. I do. The YUV converted signal is written by the CPU 101 into the VRAM 103c that stores the display image data, and is output to the LCD control unit 111 constantly using DMA.
[0052]
In step S214, the YUV signal received by the LCD control unit 111 is converted into an RGB digital signal, and then the RGB signal is output to the display driving unit 112 in step S215. In response to the output signal from the display drive unit 112, the display unit 113 displays the object scene image in step S216.
[0053]
As described above with reference to the flowchart of FIG. 2, 320 × 240 pixels in the 1/64 thinning mode when the photographic field image is dynamic, 60 frames in the refresh rate, and 1/16 thinning mode in the static case. A video of 640 × 480 pixels and a refresh rate of 30 frames is continuously monitored on the display unit 113 by continuously looping the processing from step S203 to step S216, and an EVF (electronic viewfinder) operation is performed.
[0054]
Next, description will be given of the object scene motion determination means performed in steps S209 and S210 with reference to FIGS.
[0055]
FIG. 3 is a logical block diagram constituting the object scene image motion judging means. The first frame memory 120a is an image signal obtained by A / D conversion of the object scene image signal obtained last time. The two-frame memory 120b is an image signal obtained by A / D conversion of the latest object scene image, and is stored in the memory 103.
[0056]
300a and 300b are respectively processed by the first resizing unit 301a and the second resizing unit 301b that convert the image signals of the first frame memory and the second frame memory into 80 × 60 coarse block image signals. The burden can be reduced.
[0057]
Note that even if the image signal stored in the first frame memory and the second frame memory is 320 × 240 pixels in the 1/64 thinning mode already described, it is 640 × 480 pixels in the 1/16 thinning mode. However, by performing pixel addition, the size is converted to a size of 80 × 60 pixels.
[0058]
Next, the difference calculation unit 302 obtains a difference value image obtained by taking the difference in pixel value for each corresponding pixel from the image signals of the first frame memory and the second frame memory resized to 80 × 60 image signals. Is generated. This difference value image is an image in which the image in the second frame memory is changed with respect to the image in the first frame memory, that is, an image having a significant pixel value (a value sufficiently larger than zero) only in a portion where movement has occurred. It is obtained as Therefore, an area composed of pixels having a significant pixel value included in the difference value image is detected as a moving object.
[0059]
Next, the binarization unit 303 binarizes the output of the difference calculation unit 302 using a predetermined threshold that is considered to be a significant value, whereby pixels in a region where there is a significant difference between the two images. Only 1 (ON: black), and other pixels output binarized pixel values of 0 (OFF: white). Next, the noise removal unit 304 removes isolated pixels and minute black pixel regions in the binary image caused by noise mixed due to various factors in the processing so far, and minute holes (in the black pixel connection region). A minute white pixel region is removed.
[0060]
Next, the area calculation unit 305 outputs only the pixels in the black pixel portion of the binary image, that is, outputs the black pixels as the pixel value 1 and outputs the white pixels as the pixel value 0 in this raster scanning format. By counting only one of the pixel values, the area of the extracted moving object is used as the motion level of the object scene.
[0061]
FIG. 4 is a simplified representation of the above-mentioned scene image motion determination means. When the camera photographer is trying to determine the composition of the subject to be photographed, it is used for EVF display. The captured scene image signal is displayed as an image.
[0062]
4 (a) and 4 (b) show the previous image signal stored in the first frame memory 300a and the current image signal stored in the second frame memory 300b, respectively. An image resized to an image signal of 80 × 60 pixels by 302b is shown. In both figures, 120 is the car, 121 is the background, and the position of the car 120 shown in FIG. 4 (a) has moved to the position of FIG. 4 (b) in the next frame taken in. It is shown.
[0063]
Further, each of the image signals in FIGS. 4A and 4B is subjected to image processing by the difference calculation unit 302, binarization unit 303, and noise removal unit 304, and the background region 121a as shown in FIG. 4C. Since there is no change in the image signal, it becomes the region of white pixel 0 by the differentiation process, and the overlapping region 120a accompanying the movement of the car 120 in FIGS. 4 (a) to 4 (b) also becomes the region of white pixel 0. The region 120b in which no overlap occurs due to the movement of the car 120 is detected as a region having a black pixel value of 1 because the signal component remains. By calculating the area of the black pixel value 1 by the area calculation unit 305, the degree of whether the motion of the object scene is large or not can be quantified. By comparing this numerical value with a predetermined threshold value, it is possible to determine whether or not the object scene in step S210 in FIG. 2 is dynamic.
[0064]
Even if the main subject is not moving while the framing of the camera is fixed as in the above example, even if the framing of the camera changes greatly and the entire shooting scene moves greatly, the object field Is considered dynamic. In this case as well, there is almost no need for the photographer to check the scene at high resolution (actually impossible to resolve with the eye), and the scene is projected on the EVF quickly at a high refresh rate. Needless to say, this is important.
[0065]
[Other Embodiments]
In addition, an object of each embodiment is to supply a storage medium (or recording medium) in which a program code of software that realizes the functions of the above-described embodiments is recorded to a system or apparatus, and the computer (or CPU) of the system or apparatus Needless to say, this can also be achieved by reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an operating system (OS) running on the computer based on the instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included.
[0066]
Furthermore, after the program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer, the function is determined based on the instruction of the program code. It goes without saying that the CPU or the like provided in the expansion card or the function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.
[0067]
When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the flowchart described above (shown in FIG. 2).
[0068]
In the present embodiment, an imaging unit having an imaging element that converts a scene image formed by a photographing lens into a scene image signal, and a scene image signal obtained from the imaging unit are used as a scene image. Display means for displaying on a monitor; and a scene image motion determining means for calculating a displacement amount of the scene image at a predetermined time and determining whether or not the scene image is a dynamic scene image. The electronic camera is characterized in that the resolution and the frame rate of the object scene image displayed on the display means are changed according to the result of the object scene image movement determining means. According to the present embodiment, in an electronic viewfinder type electronic camera, when shooting an intense scene such as a sports scene, the camera is automatically set to an electronic viewfinder mode with a low resolution and a high frame rate. Since the image on the finder follows the movement of the object field and can reliably determine the composition, it is possible to take a picture without missing a photo opportunity. Conversely, when shooting scenes with little movement, such as portrait and landscape shooting, the electronic viewfinder mode is set to high resolution and low frame rate, and accurate color reproduction, focus confirmation, and depth confirmation are displayed on the electronic viewfinder display screen. This makes it possible to perform shooting more faithful to the shooting intention.
[0069]
【The invention's effect】
As described above, according to the present invention, it is possible to perform an appropriate finder display corresponding to the degree of movement of the subject.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram of a digital camera according to an embodiment of the present invention.
FIG. 2 is a flowchart of an EVF function.
FIG. 3 is an explanatory block diagram of a scene image motion determination unit.
FIG. 4 is an explanatory diagram of a determination method of a scene image motion determination unit.
[Explanation of symbols]
101 CPU
106 CCD
113 Display

Claims (10)

An image pickup means having an image pickup element for converting the object scene image formed by the photographing lens into an object scene image signal;
Display means for monitoring and displaying the object scene image signal obtained from the imaging means as an object scene image;
Comparing two object scene image signals successively converted by the imaging device, the object scene image is determined based on the size of the area of the object image signal that has moved. A scene image motion determining means for determining whether the scene image is a dynamic scene image;
An image pickup apparatus comprising: control means for changing a frame rate of an object scene image displayed on the display means according to a determination result of the object scene image movement determining means.   The control means increases the frame rate in response to the scene image motion determining means determining that the scene image is a dynamic scene image. The imaging apparatus according to 1.   The imaging apparatus according to claim 1, wherein the control unit changes the resolution of the object scene image displayed on the display unit together with the change of the frame rate.   The control means has a plurality of combinations of resolutions and frame rates for displaying the scene image on the display means, and the plurality of resolutions according to a determination result of the scene image motion determination means. The imaging apparatus according to claim 3, wherein one of the frame rate combinations is determined. Imaging means having an imaging element for converting a scene image formed by the photographing lens into a scene image signal, and display means for displaying the scene image signal obtained from the imaging means as a scene image on a monitor A method of controlling an imaging apparatus comprising:
Comparing two object scene image signals successively converted by the imaging device, the object scene image is determined based on the size of the area of the object image signal that has moved. A control method for an imaging apparatus, characterized by determining whether or not the image is a dynamic object scene image, and changing a frame rate of the object image displayed on the display means in accordance with the determination result. 6. The method according to claim 5 , wherein the frame rate is increased in response to determining that the object scene image is a dynamic object scene image. The method for controlling an imaging apparatus according to claim 5 or 6 , wherein the resolution of the object scene image displayed on the display means is changed together with the change of the frame rate. A plurality of combinations of resolution and frame rate for displaying the scene image on the display means are prepared, and depending on the determination result whether the scene image is a dynamic scene image, 6. The method according to claim 5 , wherein one of a plurality of combinations of resolution and frame rate is determined. A control program for causing a computer to execute the control method according to claim 5 . A recording medium on which the control program according to claim 9 is recorded.

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