Abstract:
An image-capturing apparatus is provided having a storage control device, a writing speed measuring device, and a selecting device. The storage control device writes image data into memory devices. The writing speed measuring device measures the writing speed of the memory devices by writing dummy data into the memory devices. The selecting device compares the writing speeds of the memory devices, and selects the memory device having the fastest writing speed. The storage control device stores image data in the selected memory device.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an image-capturing apparatus, in particular to the storage of an image file in a storage medium of the image-capturing apparatus. 
         [0003]    2. Description of the Related Art 
         [0004]    An image-capturing apparatus, for example a digital camera, processes image data, and stores it in a memory device. Some digital cameras have memory devices, for example, a built-in flash memory and a detachable external memory medium. A detachable external memory medium can be a memory card, for example an SD card™, or optical disc, for example a CD-R. 
         [0005]    In general, the amount of time required to store image data in a memory device is longer than the amount of time required for imaging and processing. An overly long storage time can cause the processed image data not to be stored. It increases the interval time until the next time that the camera is ready to photograph a photographic subject. In other words, the maximum number of photographs able to be taken per second depends on the writing speed of the memory device. 
         [0006]    Some digital cameras are required to photograph a subject, continuously. Continuous photographing demands fast writing speed of the memory device. Fast writing speed increases the maximum number of photographs able to be taken per second. 
         [0007]    The writing speed of a memory device is different for different types or generations of memory. Each memory device provided in a digital camera has an attribute, for example the writing speed. A digital camera which increases the number of photographs able to be taken per second by storing the image data in a memory device having an attribute of the fastest writing speed among memory devices is disclosed in Japanese Unexamined Patent Publication (KOKAI) No. (HEI) 5-49000. 
         [0008]    However, this attribute indicates the average writing speed of a memory device. The memory area of a memory device fragments into many small areas through the repetition of storing image data. This fragmentation interferes with storage of the image data in a continuous memory area, increases writing time, seduces writing speed, and increases the difference between the actual writing speed and the average writing speed. A digital camera storing image data into a memory device having a slow writing speed due to the average writing speed being different from the actual writing speed, cannot perform to show its potential. 
       SUMMARY OF THE INVENTION 
       [0009]    An object of the present invention is to provide an image-capturing apparatus with a reduced storage time of image data, and increased maximum number of photographs able to be taken per second by choosing an optimum memory device. 
         [0010]    According to the present invention, there is provided an image-capturing apparatus comprising a storage control device writing image data in memory devices, a writing speed measuring device measuring writing speed of the memory devices by writing dummy data in the memory devices, a selecting device comparing writing speeds of the memory devices, and selecting the memory device having fastest writing speed, and the storage control device stores image data in the selected memory device. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The objects and advantages of the present invention will be better understood from the following description, with reference to the accompanying drawings in which: 
           [0012]      FIG. 1  is a block diagram showing the image-capturing apparatus as an embodiment of the present invention; 
           [0013]      FIG. 2  is a flowchart showing the initialization process; 
           [0014]      FIG. 3  is a flowchart showing the process of the measurement and comparison of writing speeds; 
           [0015]      FIG. 4  is a flowchart showing the process of creating dummy data; 
           [0016]      FIG. 5  is a flowchart showing the process of continuous photographing; 
           [0017]      FIG. 6  is a flowchart showing the image processing; 
           [0018]      FIG. 7  is a flowchart showing the process of deleting image data stored in the memory device; 
           [0019]      FIG. 8  is a flowchart showing the process of changing photographing parameter; and 
           [0020]      FIG. 9  is a flowchart showing the process of formatting the external memory medium. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    The present invention is described below with reference to the embodiments shown in the drawings.  FIG. 1  is a block diagram showing a digital camera which has an image-capturing apparatus that applies to the embodiment of the present invention. 
         [0022]    A digital camera comprises mainly a CCD/AFE (Analog Front End)  120  which converts an image formed through a lens  110  to a digital signal, a DSP (Digital Signal Processor)  130  which processes the digital signal using a ram  150  that temporarily holds the digital signal, and a built-in flash memory  150  for storing an operation program for the DSP  130 . The processed digital signal is stored in an external memory medium  170  which is provided in the digital camera as a removable storage medium, for example an SD card™. Photography information and a photographic image are displayed on an LCD  160 . The DSP  130  is connected to a switch for operating the digital camera. 
         [0023]    An instruction signal for photography is sent to the DSP  130  by operating a switch  180 . A photography subject is focused onto the CCD  120  through the lens  110 . The CCD  120  outputs an analog signal to the AFE which converts the analog signal into a digital signal. The digital signal is stored in RAM  140  as image data. These processes are carried out with the CCD/AFE  120  and the operation of the RAM  140  is executed by the control of the DSP  130 . 
         [0024]    The DSP  130  switches a control line that connects the DSP  130  with the built-in flash memory  150  or the external memory medium  170  using a connection switch  190 . In the case that the digital camera is powered on, the DSP  130  is connected to the built-in flash memory  150 , and retrieves an operation program from, the built-in flash memory  150 . In the case of photographing, image data stored into the RAM  140  is stored in a memory device, i.e. the built-in flash memory  150  or an external memory medium, that is connected to the DSP  130  by operating a connection switch  190 . 
         [0025]    The data of the image that is captured through the CCD/AFE  120  and is stored in the built-in flash memory  150  or the external memory medium  170 , may be displayed on the LCD  160  by operating an operation switch  180 . On the screen of the LCD  160 , information regarding the operation of the digital camera may also be displayed. 
         [0026]    The initializing process is described below with reference to  FIG. 2 . The first initialization process is executed in step S 210  when the digital camera is powered on by operating the operation switch  180 . The first initialization process comprises the movement of the lens  110  into a photographing position, the displaying of a star sign on the LCD  138 , the retrieving of user configuration information from the built-in flash memory  150 , and the connection of the DSP  130  with the built-in flash memory  150  or the external memory medium  170 . 
         [0027]    In step S 220 , it is judged whether the external memory medium is connected to the DSP  130 . If it is connected, the process of measurement and comparison of writing speeds is executed in step S 230 . In the case that an external memory medium is not connected, or step S 230  is finished, the second initialization process is executed in step S 240 . In the second initialization process, a photography subject focused on the CCD is displayed on the LCD  160  in real time, and the DSP  130  enables the operation of the operation switch  180 . All initialization processes are finished herewith, and preparation for photographing is finished. 
         [0028]    The process of measurement, and comparison of the writing speeds in step S 230  is described below with reference to  FIG. 3 . The remainder of the external memory medium  170  is measured in step S 332 , and dummy data is created in step S 334 . In the next step S 336 , the remainder of the external memory medium  170  is compared with the file size of the dummy data. In the case that the remainder of storable capacity in the external memory medium  170  is smaller than the file size of the dummy data, the switch flag is set to 0, and the process ends. In the case that the external memory medium has sufficient storable capacity to be write the dummy data, a timer begins to measure the amount of the time it takes to write the data in step S 350 , and the writing of the dummy data to the external memory medium  170  begins in step S 352 . In step S 353 , it is judged whether the writing of the dummy data is completed or not. In the case that writing of the dummy data is completed, the timer stops in step S 354 . The stored dummy data is deleted from the external memory medium  170  in step S 356 . In step S 358 , the writing speed is calculated in step S 358  by dividing the file size of the dummy data by the amount of storage time taken. 
         [0029]    The comparison of writing speeds is described below. The writing speed, of the built-in flash memory  150  is measured and stored in the DSP  130  in advance. The possibility of fragmentation influencing the writing or retrieving speed of the flash memory  150  is low because the built-in flash memory  150  has a small capacity and low frequency of usage. Therefore, the operating speed of the digital camera is improved by storing the writing speed of the built-in flash memory  150  beforehand. The writing speed of the external memory medium  170  is compared with the writing speed of the built-in flash memory  150  in step S 360 . In the case that the built-in flash memory  150  is faster, the switch flag is set to 1 in stop S 372 . In the case that the external memory medium  170  is faster, the switch flag is set to 0 in step S 370 . 
         [0030]    The process of creating the dummy data in step S 334  is described below with reference to  FIG. 4 . In the first step S 410 , a photographing parameter is decided, due to the file size of the dummy data being decided according to a photographing parameter. The photographing parameter is a number of pixels and an image quality. The number of pixels and the image quality is decided by the user using the operation switch  180 . According to the image quality, an average parameter is decided. The average parameter is an experimental value, and is calculated by averaging the compression ratio of various images. The file size of the dummy data is equal to the number of pixels multiplied by a certain parameter (for example ⅙), corresponding to a JPEG compression ratio, and divided by a certain parameter corresponding to the image quality set in step S 420 . After the file size of the dummy data is decided, the dummy data is stored in the RAM  140  in step S 430 , and then this process is finished. 
         [0031]    The process of continuous photographing is described below with reference to  FIG. 5 . The 
         [0032]    initialization process is executed in advance, and the switch flag is set to 0 or 1 in the initialization process. The process of continuous photographing is executed when the digital camera is set to the continuous photographing mode by a user. 
         [0033]    The Maximum number of photographs able to be taken is estimated by dividing the remainder of storable capacity in the external memory medium  170  by the predetermined image file size in step S 510 . The predetermined image file size is decided according to a photographing parameter. It is confirmed that the external memory medium  170  is connected to the DSP  130  and the switch flag is set to 1 in step S 520 . In the case of these conditions being confirmed, the built-in flash memory  150  is connected to the DSP  130  in step S 522 , and the maximum number of photographs able to be taken is estimated by dividing the remainder of storable capacity in the built-in flash memory  150  by the predetermined image file size determined according to the photographing parameter in step S 524 . In the case of these conditions not being met in step S 520 , step S 522  and S 524  are skipped. 
         [0034]    The continuous photographing number is the maximum possible number of continuously-taken photographs and decided according to a memory device connected to the DSP  130  in step S 530 . In the case that the built-in flash memory  150  is connected to the DSP  130 , the DSP  130  compares the maximum number of photographs able to be taken of the external memory medium  170  with the maximum number of photographs able to be taken of the built-in flash memory  150 . The lesser number is set as the continuous photographing number. This prevents the case that image data is not able to be stored in the external memory medium  170  after photographing. In the case that the external memory medium  170  is connected to the DSP  130 , the maximum number of photographs able to be taken of the external memory medium  170  is set as the continuous photographing number. This completes the preparation for photographing, and continuous photographing is started in step S 540 . Image data created by the DSP  130  during continuous photographing is stored in the memory medium that is connected to the DSP  130 . 
         [0035]    During continuous photographing, it is judged whether the continuous photographing is finished or not in step S 550 . This judgment is made in the case that the number of photographs taken reaches the continuous photographing number, the remainder of storable capacity in a memory device connected to the DSP  130  runs out, or the user stops the operation. A user can stop continuous photographing by releasing a release switch (not shown), turning off the power of the digital camera, or so on. 
         [0036]    When continuous photographing is finished, it is judged whether the external memory medium  170  is connected to the DSP  130  or not. In the case that it is connected, this process is finished in step S 560 . In the case that the built-in flash memory  150  is connected to the DSP  130 , image data is copied from the built-in flash memory  150  to the external memory medium  170  in step S 562 . The image data stored in the built-in flash memory  150  is deleted in step S 564 . In step S 566 , the external memory medium  170  is connected to the DSP  130 . It is judged whether the user has stopped continuous photographing in step S 568 . In the case of continuous photographing being stopped by a user, this process is finished. In the case that continuous photographing is not stopped by a user, it is judged whether the remainder of storable capacity in the external memory medium  170  has run out in step S 570 . In the case that the remainder of storable capacity in the external memory medium  170  runs out, this process is finished. In the case that the remainder of storable capacity in the external memory medium  170  does not run out, this process restarts from step S 510 . 
         [0037]    According to this embodiment, a digital camera can store image data in a memory device that has the fastest writing speed, and increase the number of photographs able to be taken per second. 
         [0038]    The second embodiment of this invention is described below with reference to  FIG. 6 .  FIG. 6  is a flowchart showing the process of measurement and comparison of writing speeds after image processing. 
         [0039]    Some digital cameras have a function to edit image data. Editing image data is done when image data retrieved from the external memory medium  170  is processed by the DSP  130 . The image can be resized, trimmed, or filtered herewith. The processed image data is then stored in the external memory medium  170 . In many cases, the image data is divided into fragments, and each fragment is stored separately in the external memory medium  170 . This causes fragmentation of the memory area. The fragmentation of the memory area decreases the writing speed into the external memory medium  170 . 
         [0040]    After the operation mode of the digital camera is changed, to the image editing mode by operating an operation switch  160  and image data is edited in step S 610 , it is selected whether the DSP  130  overwrites the image data with the edited image data or not in step S 620 . In the case that to overwrite is selected, the DSP  130  overwrites the image data in step S 630 . The DSP  130  confirms that the switch flag is 0, i.e. the external memory medium  170  is connected, in step S 632 . In the case that the switch flag is 0, the process of measurement and comparison of writing speeds is executed in step S 230 . In the case that the switch flag is not 0 in step S 632 , the process ends. 
         [0041]    In the case that to overwrite is not selected in step S 620 , it is selected whether the edited image data is to be stored separately or not in step S 640 . If separate storage is selected, the edited image data is stored in a memory device in step S 643 . If not, the edited image data is deleted in step S 640  and the process ends. 
         [0042]    The third embodiment of the invention is described below with reference to  FIG. 7 .  FIG. 7  is a flowchart showing the process of deleting image data stored in the memory device. 
         [0043]    The DSP  130  can delete image data stored in a memory device. Normally, after image data stored in a memory device is cleared, the memory area which stored the image data is released. The memory area is divided into fragments toy repeating this process of clear, consequently the writing speed of the memory device is decreased. However, the process of deleting shown in  FIG. 7  prevents a decrease of the writing speed. The image data is deleted by operating the operation switch  180  in step S 710 . In step S 720 , it is judged whether the switch flag is 0 or not. In the case that the switch flag is 0, the process of measurement and comparison of writing speeds is executed in step S 230 . The memory device which has the faster writing speed is selected herewith. In the case that the switch flag is 1 in step S 720 , i.e. the built-in flash memory  150  is connected to the DSP  130 , the process of measurement and comparison of writing speeds is not executed, and the deleting process ends. 
         [0044]    According to the second and third embodiments, if the fragmentation of a memory device decreases the writing speed, the amount of time required to store image data can be decreased by selecting a memory device having the faster writing speed. 
         [0045]    The fourth embodiment of the invention is described below with reference to  FIG. 8 . 
         [0046]    Some digital cameras have a function that changes the number of pixels in an image and the image quality, for example the image quality is the compression ratio of the image. 
         [0047]    When the number of pixels of an image or the image quality is changed, the file size of the data of the image which is photographed is changed. When the file size of the image data is changed, the amount of time required to write the image data into a memory device is changed. Therefore, it is required to select a memory device again by changing the file size of the dummy data used in the process of measurement and comparison of writing speeds. After the photographing parameters are changed in step S 810 , the process of measurement and comparison of writing speeds is executed in step S 230 . The memory device having the faster writing speed is selected herewith. 
         [0048]    According to this embodiment, even if the file size of the image data is changed, the image data may he stored in a memory device which has a writing speed suited to the file size of the image data. This prevents a decrease of the writing speed, and decreases the amount of time required to store the image data. 
         [0049]    The other embodiment of this invention is described below with reference to  FIG. 9 . 
         [0050]    A digital camera may eliminate fragmentation of the external memory medium  170  by formatting, so that the writing speed of the external memory medium  170  is increased. In the case that the external memory medium  170  is formatted in step S 910 , it is judged whether the switch flag is 1, i.e. the built-in flash memory  150  is connected to a DSP  130 , or not. When the built-in flash memory  150  is connected, the process of measurement and comparison of writing speeds is executed in step S 230 . The process inspects whether the writing speed of the external memory medium  170  has been improved. In the case that the switch flag is not 1, i.e. the external memory medium  170  is connected, the formatting process ends because the writing speed of the external memory medium  170  is faster than that of the built-in flash memory  150 . 
         [0051]    According to this embodiment, a digital camera increases the writing speed and maximum number of photographs able to be taken per second by connecting the DSP  130  to the faster memory device when an external memory medium is formatted. 
         [0052]    Note that, the process of measurement and comparison may be executed after the photographing configuration is changed to continuous photographing mode. The digital camera can decrease the amount of time required to store image data in a memory device. 
         [0053]    Note that the writing speed of the built-in flash memory  150  may be measured as well as that of the external memory medium  170 . This enables a precise comparison of the writing speeds. 
         [0054]    Note that the photographic parameter is not limited to being the number of pixels of an image, or the image quality, but may also be another parameter which changes the file size of an image. 
         [0055]    Moreover, the external memory medium  170  is not limited, to being a memory card such as an SD card™, but may also be a storage medium such as an optical disc, a hard disk, or a solid state memory. 
         [0056]    Although the embodiment of the present invention has been described herein with reference to the accompanying drawings, obviously many modifications and changes may be made by those skilled in the art without departing from the scope of the invention. 
         [0057]    The present disclosure relates to subject matter contained in Japanese Patent Application No. 2006-144517 (filed, on May 24, 2006), which is expressly incorporated herein, by reference, in its entirety.