JP2007174160A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus capable of photographing images as many as possible by reducing power consumption to be required for live view image displaying in photographing standby so as to effectively use a battery without deteriorating operability. <P>SOLUTION: When image data is displayed in a display means in the photographing standby, the imaging apparatus allows an A/D conversion control means to control the operation of an A/D converting means so as to generate image data where the number of bits is made to be smaller compared with the image data in photographing, or allows a YC conversion control means to control the operation of a YC converting part so as to generate luminance data and/or color data where the number of bits is made to be smaller compared with the luminance data and/or color data in photographing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an imaging apparatus, and more particularly to an imaging apparatus capable of reducing power consumption when displaying a shooting standby image on a display unit.

  Usually, in an image pickup apparatus represented by a digital camera, in order to perform operations such as visual recognition of a shooting standby image (hereinafter referred to as a live view image) and subtle focus adjustment on a display device in the same manner as an optical viewfinder. It has a live view function for displaying a shooting standby image on an LCD monitor or the like.

  In the photographing standby state, the image signal is taken into the image processing unit from the image sensor at a predetermined interval such as every 1/30 seconds. The captured image signal is written into the image memory in synchronization with reading of the image signal output from the image sensor. The image processing unit takes out the image data once recorded in the image memory from the image memory and performs predetermined image processing. Various image processing is performed in the image processing unit, and image data in the process is recorded in the image memory as needed to update the image data in the image memory. When the image processing is completed, the image data finally recorded in the image memory is read and a live view image is displayed on the LCD monitor or the like as a field image.

  As described above, since image data is updated every 1/30 seconds, for example, at the time of shooting standby, there is a huge amount of data to be processed by the image processing unit, the image memory, or the like. Such a large amount of data is one factor that increases the amount of power consumed in internal operations during data transfer and data processing.

  Generally, internal processing in a digital camera is configured to be performed using the power of the battery installed in the digital camera. When the power consumption of the digital camera increases, the number of images that can be shot in the digital camera decreases. become.

  Therefore, in order to effectively use the battery mounted on the digital camera and increase the number of images that can be taken by the digital camera, it is desired to reduce the power consumption in the internal operation.

For example, a technique for reducing the amount of power consumption by reducing the data processing amount per unit time by delaying the frame rate according to the shooting conditions during shooting standby is disclosed. (For example, refer to Patent Document 1).
JP 2004-15595 A

  The technique disclosed in Patent Document 1 described above reduces the power consumption by reducing the data processing amount per unit time by delaying the frame rate according to the shooting conditions during shooting standby. . However, the frame rate of a digital camera may greatly affect operability depending on the shooting scene. For example, when shooting a fast-moving subject such as a sports scene, if the frame rate is slow, the display image cannot follow the subject's movement, making composition determination difficult and missing a photo opportunity. In the case of shooting by manual focus operation, the image may be visually recognized or finely adjusted by the display device in the same way as the optical viewfinder. However, if the frame rate is slow, the display image cannot follow the change in the focus position and the shutter cannot be used. Sometimes you miss a chance. In addition, when performing autofocus adjustment based on image data, there is a problem that if the frame rate is slow, the autofocus speed is slowed and a photo opportunity is missed.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an imaging device capable of effectively using a battery and taking a large number of images without losing operability. . Specifically, the live view image is an image for visual recognition when performing operations such as composition determination and focus adjustment at the time of shooting, and may not require a clear color image as at the time of shooting. In view of this, the present invention reduces the number of bits per pixel when the image signal output from the image sensor is A / D converted to generate image data during shooting standby, and is processed by the image processing unit. Image pickup apparatus capable of reducing the power consumption amount by reducing the number of bits per pixel of luminance data and color data to be processed and reducing the amount of data to be processed, and capable of capturing as many images as possible I will provide a.

  The above object is achieved by the invention described in any one of 1 to 7 below.

1. Imaging means for photoelectrically converting a subject optical image to generate an image signal;
A / D conversion means for A / D converting the image signal generated by the imaging means to generate image data;
A / D conversion control means for controlling the operation of the A / D conversion means;
Image processing means for performing predetermined processing on the image data generated by the A / D conversion means;
Storage means for storing image data processed by the image processing means;
An image pickup apparatus comprising: display means for displaying image data stored in the storage means;
When displaying the image data on the display means during shooting standby,
The A / D conversion control means controls the operation of the A / D conversion means so as to generate image data in which the number of bits per pixel is smaller than the image data generated at the time of photographing. An imaging device.

2. Imaging means for photoelectrically converting a subject optical image to generate an image signal;
A / D conversion means for A / D converting the image signal generated by the imaging means to generate image data;
Image processing means having a YC conversion section for YC converting the image data generated by the A / D conversion means to generate luminance data and color data;
YC conversion control means for controlling the operation of the YC conversion unit;
Storage means for storing image data processed by the image processing means;
An image pickup apparatus comprising: display means for displaying image data stored in the storage means;
When displaying the image data on the display means during shooting standby,
The YC conversion control means controls the operation of the YC conversion unit so as to generate luminance data and / or color data having a smaller number of bits per pixel than luminance data and / or color data generated at the time of photographing. An imaging device characterized by being a thing.

3. The YC conversion control means is
When displaying the image data on the display means during shooting standby,
3. The imaging apparatus according to 2, wherein the operation of the YC conversion unit is controlled so as to generate only the luminance data.

4). The imaging device
Detection means for detecting the capacity of the battery stored in the imaging device;
Control means for controlling the operation of at least one of the A / D conversion control means and the YC conversion control means,
When displaying the image data on the display means in a shooting standby state,
When the detecting means detects that the capacity of the battery is lower than a preset reference capacity,
The control means controls the operation of the A / D conversion means so that the A / D conversion control means generates image data having a smaller number of bits per pixel than image data generated at the time of photographing. To control or
The YC conversion control means controls the operation of the YC conversion unit so as to generate luminance data and / or color data having a smaller number of bits per pixel than luminance data and / or color data generated at the time of photographing. The imaging apparatus according to any one of 1 to 3, wherein the imaging apparatus is controlled as follows.

5. The imaging device includes an image processing IC having a buffer memory for storing image data generated in a processing process performed on the image data generated by the A / D conversion unit, and a processing process performed by the image processing IC. A memory IC for storing image data;
When displaying the image data on the display means during shooting standby,
5. The imaging apparatus according to any one of claims 1 to 4, wherein the image processing IC does not communicate image data with the memory IC.

  6). 6. The imaging apparatus according to 5, wherein at least the imaging unit having the imaging element, the A / D conversion unit, and the image processing IC are configured by a one-chip IC.

  7). The number of bits of image data per pixel generated by the A / D conversion means, or the number of bits of luminance data and color data per pixel generated by the YC conversion unit is a multiple of 2. The imaging apparatus according to any one of 1 to 6.

  According to the present invention, when a live view image is displayed on the display unit during shooting standby, the A / D conversion control unit generates image data with a smaller number of bits per pixel than image data generated during shooting. In this way, the operation of the A / D conversion means is controlled. Therefore, at the time of shooting standby where high image quality is not required, the amount of data to be processed by the image processing means and the storage means is reduced by reducing the image data generated by the A / D conversion means, and data transfer and data processing In this case, the amount of power consumed in the internal operation can be reduced.

  In addition, when displaying a live view image on the display unit during shooting standby, the YC conversion control unit uses luminance data and / or color in which the number of bits per pixel is smaller than luminance data and / or color data generated during shooting. The operation of the YC converter is controlled so as to generate data. Therefore, at the time of shooting standby where high image quality is not required, the amount of data to be processed by the image processing means and storage means is reduced by reducing the luminance data and / or color data generated by the YC conversion unit, and data transfer In addition, the amount of power consumed in internal operations during data processing can be reduced.

  Further, the YC conversion control means controls the operation of the YC conversion section so as to generate only the luminance data when displaying the image data on the display means at the time of shooting standby. Therefore, at the time of shooting standby where a color image is not always required, the amount of data to be processed by the image processing unit and the storage unit is greatly reduced by deleting the color data generated by the YC conversion unit, and data transfer and data processing can be performed. In this case, the amount of power consumed in the internal operation can be greatly reduced.

  Further, when displaying the image data on the display means in the shooting standby state, if the detecting means detects that the battery capacity is lower than a preset reference capacity, the control means performs A / D conversion. The control means controls to control the operation of the A / D conversion means so as to generate image data having a smaller number of bits per pixel than the image data generated at the time of shooting, or the YC conversion control means The operation of the YC converter is controlled so as to generate luminance data and / or color data in which the number of bits per pixel is smaller than the luminance data and / or color data generated during shooting. Therefore, even in a situation where the capacity of the battery is reduced, many good images can be obtained even with one sheet.

  Also, when displaying an image on the display means during shooting standby, the image processing IC processes image data using a buffer memory provided inside the image processing IC, and the memory IC provided outside the image processing IC is I didn't use it. Usually, the buffer memory provided in the image processing IC has a relatively small storage capacity and may not be able to store various image data generated in the image processing process during shooting standby. A memory IC having a large storage capacity, such as a DRAM (Dynamic Random Access Memory) provided outside the computer, is used. However, since the image data by the A / D conversion means or the luminance data and the color data by the YC conversion unit are reduced at the time of shooting standby, the image data processed by the image processing IC is greatly reduced. Processing can be performed with a buffer memory having a relatively small storage capacity without using a memory IC having a large capacity. Accordingly, during standby for shooting, image processing is performed using a buffer memory with low power consumption instead of using a memory IC with high power consumption. Therefore, power consumed in internal operations during data transfer and data processing The amount can be reduced.

  Further, at least the image sensor, the A / D conversion means, and the image processing IC are configured by a one-chip IC. Accordingly, for example, in a CMOS (Complementary Metal-Oxide Semiconductor) type solid-state imaging device, various processes necessary for shooting standby can be performed inside the CMOS 1-chip IC. By stopping the power supply, it is possible to reduce the amount of power consumed, and by using a single chip, the component cost can be reduced.

  Further, the number of bits of image data per pixel generated by the A / D conversion means, or the number of bits of luminance data and color data per pixel generated by the YC conversion unit is set to a multiple of two. Therefore, the vertical direction can be used effectively in the arrangement of the storage means.

  Embodiments of an imaging apparatus according to the present invention will be described below with reference to the drawings. In addition, in each figure, the same code | symbol shows the same or an equivalent part, and the overlapping description is abbreviate | omitted.

  As a specific embodiment of the imaging apparatus according to the present invention, a digital camera is typical, but a mobile phone with a camera is also included.

Embodiment 1
First, the external appearance of a digital camera 1 that is one of representative embodiments of an imaging apparatus according to the present invention will be described with reference to FIG.

  FIG. 1A is a perspective view of the digital camera 1 according to the present invention as viewed obliquely from the front, and FIG. 1B is a rear view.

  The digital camera 1 has an LCD monitor 107 composed of an LCD (Liquid Crystal Display), a finder 108, and an external connection terminal for connecting the digital camera 1 to a personal computer (not shown). The image signal captured by the sensor 251 (hereinafter abbreviated as the CCD 251) is subjected to predetermined signal processing, and a live view display of the shooting standby image on the LCD monitor 107 and an image on a recording medium such as a memory card 177 to be described later. Processing such as recording, reproduction display of the recorded image on the LCD monitor 107, or transfer of the image to a personal computer is performed.

  As shown in FIG. 1A, a shutter button 101 and a power button 102 are provided on the upper surface of the digital camera 1. The shutter button 101 has a two-stage push stroke. AF (Auto Focus) control and AE (Auto Exposure) control are activated by “half-pressing” to lock AF and AE. Is done. Further, shooting (shooting for recording) is performed in a state of “full press” in which the “half press” is further pressed.

  A flash 103 and a photographing lens window 104 are provided in front of the digital camera 1, and a zoom lens 20 (not shown) is provided inside the photographing lens window 104.

  Further, as shown in FIG. 1B, an LCD monitor 107 is provided in the center of the back surface of the digital camera 1 for performing live view display of a shooting standby image, playback display of recorded images, various information displays, and the like. Yes. Further, a jog dial (cross key) 109 for performing various settings is provided in the vicinity of the LCD monitor 107. The jog dial (cross key) 109 also serves as a zoom operation button. A mode selection dial 110 for switching the operation mode of the digital camera 1 is provided in the vicinity of the LCD monitor 107. The operation mode of the digital camera 1 includes, for example, a still image shooting mode, a moving image shooting mode, and a playback mode. A mode setting button group 111 is provided in the vicinity of the LCD monitor 107. The mode buttons 111a to 111d include a power saving mode ON / OFF button 111d.

  Next, the control system of the digital camera 1 will be described with reference to FIG. FIG. 2 is a circuit block diagram of the digital camera 1 according to the present invention.

  The aperture / shutter 253 and the focus / zoom motor 254 operate according to control signals sent from a camera control CPU 181 to be described later via an aperture / shutter drive circuit 157 and a focus / zoom motor drive circuit 158, respectively.

  The CCD 251 corresponds to the imaging means in the present invention, and is a color area in which each color transmission filter of R (red) light, G (green) light, and B (blue) light is arranged in a checkered pattern in pixel units (pixel units). A subject light image formed by the zoom lens 20 by the imaging sensor is converted into an image signal of each color component of R (red) light, G (green) light, and B (blue) light (pixel signal received in units of pixels). The signal is converted into a signal).

  The analog signal processing unit 152 includes a timing generator 156, a CDS circuit 153, an AGC circuit 154, an A / D converter 155, and an A / D buffer 159, and a predetermined process is performed on the image signal via these components. Done. Hereinafter, a predetermined process for the image signal performed by the analog signal processing unit 152 will be described.

  The timing generator 156 generates a drive control signal for the CCD 251 based on a reference clock transmitted from a reference clock generator 171 described later. The drive control signal generated by the timing generator 156 includes, for example, an integration start / end timing signal for controlling the exposure start and end timings in the CCD 251, and a readout control signal (horizontal synchronization signal, vertical synchronization) of the light reception signal of each pixel. Clock signals such as signals, transfer signals, and the like. When these clock signals are supplied to the CCD 251, the CCD 251 performs drive control corresponding to each clock signal. The operation of the timing generator 156 is controlled by a camera control CPU 181 described later.

  A CDS (Correlated Double Sampling) circuit 153 reduces noise generated during reading from the image signal read from the CCD 251 and corrects dark noise by OB clamping operation.

  An AGC (automatic gain control) circuit 154 adjusts the gain of the image signal processed by the CDS circuit 153.

  The A / D converter 155 converts each pixel signal constituting the image signal input from the AGC circuit 154 into a digital signal. The A / D converter 155 converts each pixel signal of the analog signal into, for example, 12-bit digital image data based on the A / D conversion clock input from the reference clock generation unit 171.

  The A / D buffer 159 operates the number of bits of the image data A / D converted by the A / D converter 155 based on the control of the camera control CPU 181 at the time of shooting standby.

  Specifically, this will be described with reference to FIG. FIG. 3A is a schematic diagram showing output data of the A / D buffer 159 during still image or moving image shooting. FIG. 3B is a schematic diagram showing output data of the A / D buffer 159 during shooting standby.

  At the time of shooting a still image or a moving image, the A / D buffer 159 outputs the image data to the image processing CPU 161 described later without reducing the number of bits of, for example, 12-bit image data A / D converted by the A / D converter 155. To do. At this time, as the image data output from the A / D buffer 159, as shown in FIG. 3A, image data for 2 pixels is output in 3 bytes. On the other hand, during shooting standby, the A / D buffer 159 reduces, for example, the lower 4 bits of the 12-bit image data A / D converted by the A / D converter 155 and outputs the reduced data to the image processing CPU 161. At this time, the image data output from the A / D buffer 159 is, as shown in FIG. 3B, the image data for one pixel is 8 bits, so the image data for 3 pixels is output in 3 bytes. Will be. That is, at the time of shooting standby, the image data for one pixel is reduced to 2/3 of that for shooting a still image or a moving image. As described above, when displaying a live view image at the time of shooting standby in which a high-quality image such as still image or moving image shooting is not always necessary, image data output from the A / D buffer 159 is reduced. As a result, the amount of data to be processed by the image processing CPU 161 and the image memory 175, which will be described later, is reduced, and the amount of power consumed in internal operations during data transfer and data processing can be reduced. That is, the A / D converter 155 and the A / D buffer 159 function as A / D conversion means in the imaging apparatus according to the present invention. Details of the power saving operation performed by the digital camera 1 will be described later.

  In this manner, the image signal read by the CCD 251 is subjected to predetermined processing by the analog signal processing unit 152 and converted into digital image data. The digitized image data is captured by the image processing CPU 161 and subjected to predetermined processing.

  The image processing CPU 161 corresponds to the image processing means and the image processing IC in the present invention, and is composed of a microcomputer and comprehensively controls image signal processing operations performed by the digital camera 1. Hereinafter, a process for digital image data performed by the image processing CPU 161 will be described.

  First, the image data captured by the image processing CPU 161 is written in the image memory 175 corresponding to the storage means and the memory IC in the present invention in synchronization with the reading of the image signal output from the CCD 251. That is, the image data used in the processing performed by the image processing CPU 161 is once recorded in the image memory 175, taken out from the image memory 175, and used for processing in each block.

  As shown in FIG. 2, the image processing CPU 161 includes, for example, a black level correction unit 163, a pixel interpolation unit 164, a resolution conversion unit 165, a white balance control unit 166, a gamma correction unit 167, a matrix calculation unit 168, a shading correction unit 169, The image processing unit 162 includes an image compression unit 170, a reference clock generation unit 171, a buffer memory 172, and the like. The image processing unit 162 performs well-known image processing on image data extracted from the image memory 175. . Then, the image data that has undergone predetermined processing at these parts is stored again in the image memory 175.

  The reference clock generation unit 171 is a circuit that generates a reference clock used for driving control of the digital camera 1 and supplies the reference clock to each circuit. Specific examples of the reference clock in the present invention include a reference clock used for the timing generator 156, an A / D conversion clock used for the A / D converter 155, and the like. Generate a clock.

  The buffer memory 172 temporarily stores image data with a relatively small amount of data generated in the course of processing in the image processing unit 162.

  Next, the LCD monitor 107 corresponds to the display means in the present invention, and performs display of a live view image captured by the CCD 251, reproduction display of a recorded image, various information display, and the like.

  The LCD drive circuit 183 includes a buffer memory (VRAM) that temporarily stores image data read from the image memory 175 by the image processing CPU 161, and displays the image data on the LCD monitor 107 as a field image.

  The DC / DC converter 186 converts the voltage of the battery 185 as an operation power source of the digital camera 1 into a necessary voltage for each part of the digital camera 1 and supplies the converted voltage.

  Next, the camera control CPU 181 is composed of a microcomputer, and based on each switch operation of a switch group 191 to be described later, the driving of each member constituting the digital camera 1 is sequentially controlled to comprehensively control the photographing operation of the digital camera 1. To do.

  The camera control CPU 181 corresponds to the A / D conversion control means in the present invention, and controls the A / D buffer 159 during imaging standby, and the bit of the image data A / D converted by the A / D converter 155. Manipulate numbers.

  The camera control CPU 181 corresponds to the detection means in the present invention and detects the remaining capacity of the battery 185.

  The camera control CPU 181 corresponds to a control unit in the present invention, and controls a power saving operation performed in the digital camera 1 based on the detected remaining capacity of the battery 185.

  The digital camera 1 according to the present invention records an image signal captured by the CCD 251 in the image memory 175 or displays it on the LCD monitor 107 under a mode set by various operation switches of the switch group 191.

  In the photographing standby state, image signals are taken into the image processing CPU 161 from the CCD 251 via the analog signal processing unit 152 at a predetermined interval such as every 1/30 seconds. The captured image data is subjected to predetermined signal processing at a portion from the black level correction unit 163 to the shading correction unit 169 of the image processing unit 162 in the image processing CPU 161 as described above, and then recorded in the image memory 175. Is done. Then, the image data recorded in the image memory 175 is read, and the live image is displayed on the LCD monitor 107 by using the read image data as a field image via the LCD drive circuit 183.

  At the time of image recording, the image data is compressed by the image compression unit 170 of the image processing unit 162 in the image processing CPU 161 in order to obtain an image of the set recording resolution, and the obtained compressed image is stored in the memory card driver 176. To the memory card 177.

  At the time of reproduction, the image data read from the memory card 177 is subjected to predetermined signal processing by the image processing CPU 161 and displayed on the LCD monitor 107 via the LCD driving circuit 183.

  2 are switches corresponding to the shutter button 101, the power button 102, the jog dial key (cross key) 109, the mode selection dial 110, the mode setting button group 111, and the like in FIG.

  Here, the flow of the power saving operation performed in the digital camera 1 according to the present invention will be described in detail with reference to the flowchart shown in FIG.

  First, when the digital camera 1 is set to the still image shooting mode (step S1), the camera control CPU 181 sets the digital camera 1 to a shooting standby state, and the CCD 251 starts capturing an image signal (step S2). When the image signal is captured from the CCD 251, the A / D converter 155 A / D converts the image signal captured from the CCD 251 into, for example, 12-bit image data (step S3). Next, the camera control CPU 181 controls the lower 4 bits of the A / D buffer 159 so that, for example, the lower 4 bits of the 12-bit image data A / D converted by the A / D converter 155 are not output to the image processing CPU 161. Is turned off (step S4), and the upper 8-bit image data is output to the image processing CPU 161 (step S5). Next, the camera control CPU 181 changes the operation of the image processing CPU 161 from the 12-bit mode to the 8-bit mode (step S6). When the operation mode is set to the 8-bit mode, the image processing CPU 161 performs the predetermined image processing described above on the 8-bit image data output from the A / D buffer 159 (step S7), and displays the live view image on the LCD. The information is displayed on the monitor 107 (step S8).

  As described above, in the present invention, when a live view image is displayed at the time of shooting standby in which a high-quality image such as still image or moving image shooting is not always necessary, an image output from the A / D buffer 159 is used. The data was reduced and the live view image was displayed. Therefore, the amount of data to be processed by the image processing CPU 161 and the image memory 175 can be reduced, and the amount of power consumed in internal operations can be reduced during data transfer and data processing.

  In the first embodiment of the present invention, the camera control CPU 181 always performs the power saving operation during shooting standby. For example, the user operates the power saving mode ON / OFF button 111d as necessary. By doing so, the power saving operation may be executed. Further, the camera control CPU 181 may execute the power saving operation when the remaining capacity of the battery 185 decreases to a predetermined capacity or less. In this way, even in a situation where the remaining capacity of the loaded battery 185 is reduced, it is possible to suppress power consumption and obtain many good images.

[Embodiment 2]
Next, a second embodiment of the imaging device according to the present invention will be described. The configuration of the main part is substantially the same as that of the above-described first embodiment, and thus detailed description thereof will be omitted, and only parts different in operation from the first embodiment will be described.

  The digital camera according to the first embodiment reduces the amount of data to be processed by the image processing CPU 161 and the image memory 175 by reducing the image data output from the A / D buffer 159 at the time of shooting standby. However, the digital camera 1 according to the second embodiment does not operate the image data by the A / D buffer 159, and the image processing in the image processing CPU 161 is performed. The amount of power consumed is reduced by reducing the luminance data and / or color difference data output from the matrix calculation unit 168 of the unit 162.

  The matrix calculation unit 168 corresponds to the YC conversion unit in the present invention, and the luminance data (R, G, B image data pixel-complemented by the pixel complementation unit 164 of the image processing unit 162 is converted into luminance data ( Y) and color difference data (Cr: (R−Y) and Cb: (B−Y)), and the converted luminance data and color difference data are converted into a data configuration conforming to the YCrCb422 format described later. .

  The matrix calculation unit 168 manipulates the number of bits of the converted luminance data and / or color difference data based on the control of the camera control CPU 181 corresponding to the YC conversion control means in the present invention at the time of shooting standby.

  Specifically, this will be described with reference to FIG. FIG. 4A is a schematic diagram showing output data of the matrix calculation unit 168 when shooting a still image or a moving image. FIG. 4B is a schematic diagram showing output data of the matrix calculation unit 168 during shooting standby.

  As the configuration of the luminance data and the color difference data handled by the image processing unit 162, a data configuration conforming to the YCrCb422 format is usually used. That is, the luminance data and the color difference data are configured at a ratio of Y: Cr: Cb = 2: 1: 1. Specifically, as shown in FIG. 4A, when an 8-bit data amount is assigned to each data unit of luminance data and color difference data, data for 8 pixels (Y: 8 data) , Cr: 4 data, Cb: 4 data), 16 bytes.

  At the time of taking a still image or a moving image, the matrix calculation unit 168 uses the luminance data and color difference composed of, for example, normal 16 bytes as data for 8 pixels (Y: 8 data, Cr: 4 data, Cb: 4 data). The data is output as it is without reducing the number of bits. On the other hand, at the time of shooting standby, as shown in FIG. 4B, the matrix calculation unit 168 reduces, for example, the lower 2 bits of converted luminance data and / or color difference data to 6 bits per converted data, as shown in FIG. Luminance data and / or color difference data composed of 12 bytes are output. That is, at the time of shooting standby, the image data for 8 pixels is reduced to 3/4 of that at the time of shooting a still image or a moving image. In this way, when displaying a live view image during shooting standby in which high-quality images such as still images and moving images are not always required, luminance data and / or color differences output from the matrix calculation unit 168 are displayed. By reducing the data, the amount of data to be processed by the image processing CPU 161 and the image memory 175 can be reduced, and the amount of power consumed in internal operations during data transfer and data processing can be reduced.

  If the input data format of the LCD drive circuit 183 or the LCD monitor 107 is different, it may be converted into a suitable format and input, for example, the input of the LCD drive circuit 183 corresponds to a YCrCb 8-bit input. If the data is input from the image processing CPU 161 to the LCD drive circuit 183, 2 bits “00”, for example, may be added to the lower order of the 6-bit luminance data and / or the color difference data to obtain 8 bits. .

  Here, the flow of the power saving operation performed in the digital camera 1 according to the present invention will be described in detail with reference to the flowchart shown in FIG.

  First, when the digital camera 1 is set to the still image shooting mode (step S1), the camera control CPU 181 sets the digital camera 1 to a shooting standby state, and the CCD 251 starts capturing an image signal (step S2). When the image signal captured from the CCD 251 is subjected to the above-described predetermined processing by the analog signal processing unit 152 and output to the image processing CPU 161, the matrix calculation unit 168 outputs the R, G, and R output from the analog signal processing unit 152. The B image data is converted into 8-bit luminance data and color difference data (step S3). Next, the camera control CPU 181 controls the matrix calculation unit 168 to delete the lower 2 bits of the converted 8-bit luminance data and / or chrominance data, and to perform luminance data and / or compliant with the 6-bit YCrCb422 format. Or it converts into color difference data (step S4). Next, the image processing CPU 161 performs the predetermined image processing described above on the luminance data and / or color difference data compliant with the 6-bit YCrCb422 format output from the matrix calculation unit 168 (step S5), and the live view image is displayed on the LCD. The information is displayed on the monitor 107 (step S6).

  As described above, in the present invention, luminance data output from the matrix calculation unit 168 is displayed when a live view image is displayed at the time of shooting standby, in which a high-quality image such as still image or moving image shooting is not always necessary. In addition, the color difference data is reduced and the live view image is displayed. Therefore, the amount of data to be processed by the image processing CPU 161 and the image memory 175 can be reduced, and the amount of power consumed in internal operations can be reduced during data transfer and data processing.

  In the second embodiment of the present invention, at the time of shooting standby, the camera control CPU 181 reduces the amount of power consumed by reducing the luminance data and / or color difference data output from the matrix calculation unit 168. However, for example, when the remaining capacity of the battery 185 decreases, the camera control CPU 181 deletes the color difference data from the luminance data and color difference data output from the matrix calculation unit 168 and outputs only the luminance data. Alternatively, a black and white live view image may be displayed. By doing so, the amount of data to be processed by the image processing CPU 161 and the image memory 175 is greatly reduced, and even in a situation where the remaining capacity of the battery 185 is reduced, the power consumption is suppressed and even a single sheet is good. Can be obtained. In addition, when the remaining capacity of the battery 185 decreases, the live view image changes from color display to black and white display, so that the user can visually recognize that the remaining capacity of the battery 185 has decreased.

  The present invention has been described above with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be changed or improved as appropriate. For example, in the digital camera 1 described in the first and second embodiments, the image processing CPU 161 performs various image processing using the image memory 175 (memory IC) during shooting standby. Various image processing may be performed using a buffer memory 172 provided inside.

  Normally, the buffer memory 172 provided in the image processing IC 161 has a relatively small storage capacity, and may not be able to store various image data generated in the image processing process during shooting standby. An image memory 175 (memory IC) having a large storage capacity such as (Dynamic Random Access Memory) was used. However, since image data by the A / D buffer 159 or luminance data and / or color data is reduced by the matrix calculation unit 168 during shooting standby, the image data processed by the image processing IC 161 is greatly reduced. Therefore, processing can be performed with a buffer memory having a relatively small storage capacity without using the image memory 175 (memory IC) having a large storage capacity. Therefore, at the time of shooting standby, image processing is performed using the buffer memory 172 with low power consumption without using the image memory 175 (memory IC) with high power consumption, so that internal operations can be performed during data transfer and data processing. The amount of power consumed can be greatly reduced.

  In the digital camera 1 described in the first and second embodiments, the CCD 251, the analog signal processing unit 152, and the image processing CPU 161 are configured with different parts, but a CMOS solid-state image sensor or the like is used as the image sensor. In such a case, at least the image sensor, the A / D converter 155, the A / D buffer 159, and the image processing CPU 161 may be configured by a one-chip CMOS IC. By adopting such a configuration, various processes necessary for shooting standby can be performed inside the CMOS 1 chip IC, so that power supply to an external image memory 175 (memory IC) or the like is stopped. As a result, the amount of power consumed can be reduced, and component costs can be reduced by using one chip.

1 is a schematic external view of a digital camera according to the present invention. 1 is a circuit block configuration diagram of a digital camera according to the present invention. It is a schematic diagram which shows the output data of the A / D buffer by Embodiment 1 in this invention. It is a schematic diagram which shows the output data of the matrix calculating part by Embodiment 2 in this invention. It is a flowchart which shows the flow of the power saving control of the digital camera by Embodiment 1 in this invention. It is a flowchart which shows the flow of the power saving control of the digital camera by Embodiment 2 in this invention.

Explanation of symbols

1 Digital Camera 101 Shutter Button 102 Power Button 103 Flash 104 Shooting Lens Window 107 LCD Monitor 109 Jog Dial Key (Cross Key)
110 Mode selection dial 111 Mode setting button group 152 Analog signal processing unit 153 CDS circuit 154 AGC circuit 155 A / D converter 156 Timing generator 157 Aperture / shutter drive circuit 158 Focus / zoom motor drive circuit 159 A / D buffer 161 Image processing CPU
162 Image processing unit 163 Black level correction unit 164 Pixel complementation unit 165 Resolution conversion unit 166 White balance control unit 167 Gamma correction unit 168 Matrix calculation unit 169 Shading correction unit 170 Image compression unit 171 Reference clock generation unit 172 Buffer memory 175 Image memory 176 Memory card driver 177 Memory card 178 External communication I / F
181 Camera control CPU
183 LCD drive circuit 185 Battery 186 DC / DC converter 191 Switch group (shutter button, etc.)
20 Zoom lens 251 CCD color area sensor 253 Aperture / shutter 254 Focus / zoom motor

Claims (7)

Imaging means for photoelectrically converting a subject optical image to generate an image signal;
A / D conversion means for A / D converting the image signal generated by the imaging means to generate image data;
A / D conversion control means for controlling the operation of the A / D conversion means;
Image processing means for performing predetermined processing on the image data generated by the A / D conversion means;
Storage means for storing image data processed by the image processing means;
An image pickup apparatus comprising: display means for displaying image data stored in the storage means;
When displaying the image data on the display means during shooting standby,
The A / D conversion control means controls the operation of the A / D conversion means so as to generate image data in which the number of bits per pixel is smaller than the image data generated at the time of photographing. An imaging device. Imaging means for photoelectrically converting a subject optical image to generate an image signal;
A / D conversion means for A / D converting the image signal generated by the imaging means to generate image data;
Image processing means having a YC conversion section for YC converting the image data generated by the A / D conversion means to generate luminance data and color data;
YC conversion control means for controlling the operation of the YC conversion unit;
Storage means for storing image data processed by the image processing means;
An image pickup apparatus comprising: display means for displaying image data stored in the storage means;
When displaying the image data on the display means during shooting standby,
The YC conversion control means controls the operation of the YC conversion unit so as to generate luminance data and / or color data having a smaller number of bits per pixel than luminance data and / or color data generated at the time of photographing. An imaging device characterized by being a thing. The YC conversion control means is
When displaying the image data on the display means during shooting standby,
The imaging apparatus according to claim 2, wherein the operation of the YC conversion unit is controlled so as to generate only the luminance data. The imaging device
Detection means for detecting the capacity of the battery stored in the imaging device;
Control means for controlling the operation of at least one of the A / D conversion control means and the YC conversion control means,
When displaying the image data on the display means in a shooting standby state,
When the detecting means detects that the capacity of the battery is lower than a preset reference capacity,
The control means controls the operation of the A / D conversion means so that the A / D conversion control means generates image data having a smaller number of bits per pixel than image data generated at the time of photographing. To control or
The YC conversion control means controls the operation of the YC conversion unit so as to generate luminance data and / or color data having a smaller number of bits per pixel than luminance data and / or color data generated at the time of photographing. The imaging apparatus according to claim 1, wherein the imaging apparatus is controlled as follows. The imaging device includes an image processing IC having a buffer memory for storing image data generated in a processing process performed on the image data generated by the A / D conversion unit, and a processing process performed by the image processing IC. A memory IC for storing image data;
When displaying the image data on the display means during shooting standby,
The imaging apparatus according to claim 1, wherein the image processing IC does not exchange image data with the memory IC. The imaging apparatus according to claim 5, wherein at least the imaging unit including the imaging element, the A / D conversion unit, and the image processing IC are configured by a one-chip IC. The number of bits of image data per pixel generated by the A / D conversion means, or the number of bits of luminance data and color data per pixel generated by the YC conversion unit is a multiple of 2. The imaging device according to any one of claims 1 to 6.

Images