Abstract:
An image capture apparatus includes an image capture unit, an internal memory, a digital communication unit, a display unit and a control unit. The image capture unit captures an image. The internal memory stores the captured image. The digital communication unit sends the captured image stored in the internal memory to an external device. The control unit (i) selects a low-speed transfer mode if the display unit displays an image, and (ii) selects a high-speed transfer mode if the display unit does not display an image. Both the low-speed transfer mode and the high-speed transfer mode are used for transfer of data between the internal memory and the digital communication unit for transfer of the captured image to the external device.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an apparatus which generates still image data of an object. 
   2. Description of the Related Art 
   A known apparatus for generating still image data is a digital camera. 
   In a known digital camera, in processing for displaying display data (such as a frame of reduced image data of still image data generated by an image capture apparatus or read from a removable storage medium, or menu-panel data for illustrating a menu panel) on a display unit, when data to be written in an external apparatus is transferred from an internal memory to a digital interface unit or when data read from the external apparatus is transferred from the digital interface unit to the internal memory by a DMA (direct memory access) transfer, a display processing problem (for example, a delay in the display processing) is likely to occur, whereby the display data is sometimes displayed in an disarranged manner. 
   Also, in a known digital camera, in processing for continuously generating a plurality of frames of still image data (that is, in continuous capture processing), when data to be written in the external apparatus is transferred from the internal memory to the digital interface unit or when data read from the external apparatus is transferred from the digital interface unit to the internal memory by DMA transfer, a continuous capture processing problem (for example, a delay in photometric control processing, or in image processing) is likely to occur, whereby the frames of still image data are generated in an disarranged manner. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to overcome the above-described drawbacks. 
   Another object of the present invention is to provide an image capture apparatus which writes data in an external apparatus and reads out data from the external apparatus without causing a display processing problem or a continuous capture processing problem to occur. 
   An image capture apparatus according to a preferred embodiment of the present embodiment comprises storage means and digital communication means. A transfer mode between the storage means and the digital communication means is changed in accordance with an operating state of the image capture apparatus. 
   Still other objects, features and advantages of the present invention will become fully apparent from the following detailed description of the preferred embodiments with reference to the attached drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates an image capture system according to an embodiment of the present invention. 
       FIG. 2  illustrates the structure of a digital camera shown in  FIG. 1 . 
       FIG. 3  illustrates an example process procedure for controlling a transfer mode between an upper memory and a digital interface unit (DIU) shown in  FIG. 2 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   A preferred embodiment of the present invention will be described with reference to  FIGS. 1 to 3 . 
     FIG. 1  is a block diagram illustrating an image capture system according to a preferred embodiment of the present invention. 
   A digital camera  10  is an image capture apparatus according to the present embodiment. The digital camera  10  has a drive mode in which still image data and corresponding additional data are generated (hereinafter, referred to as an single-frame capture mode), and another drive mode in which a plurality of frames of still image data and corresponding additional data are continuously generated at specified time intervals (hereinafter, referred to as a continuous capture mode). A PC (personal computer)  20  is a controller according to the present embodiment. A storage medium  30  stores a program for operating the digital camera  10  by remote control (hereinafter, referred to as a camera-control program). 
   The PC  20  installs the camera-control program from the storage medium  30  and controls the digital camera  10  in accordance with the installed camera-control program. When the PC  20  is to read data such as still image data from the digital camera  10 , the PC  20  transmits a command block ORB (operation request block) including a READ ( 10 ) command to the digital camera  10 . When the PC  20  is to write data such as set data in the digital camera  10 , the PC  20  transmits the command block ORB including a WRITE ( 10 ) command to the digital camera  10 . The command block ORB is one of the requests defined by SBP-2 (Serial Bus Protocol 2) and stores SCSI (small computer system interface) commands such as the READ ( 10 ) command and the WRITE ( 10 ) command. The SBP-2 is a communication protocol defined by ISO/IEC 14776-232. 
   Referring next to  FIG. 2 , the structure of the digital camera  10  according to the present embodiment will be described. 
   An image capture unit  101  is means for generating still image data of an object and corresponding additional data. When the digital camera  10  is in the single-frame capture mode, the image capture unit  101  generates a frame of still image data and corresponding additional data. This data is temporally stored in a memory  102 . Meanwhile, when the digital camera  10  is in the continuous capture mode, the image capture unit  101  continuously generates still image data and corresponding additional data at specified time intervals. This data is also temporally stored in memory  102 . A photometric control unit  1011  controls the photometric processing of the image capture unit  101  in accordance with one of a plurality of photometric modes. The photometric modes can be selected with a photometric mode button of an operation unit  109 . 
   The memory  102  is high-speed, large-capacity storage means to which random access is permitted. The memory  102  temporally stores data for a predetermined number of still images obtained from the image capture unit  101  or a storage medium  111 , the corresponding additional data, and reduced image data of the still image data. In addition, the memory  102  also stores menu-panel data to be displayed on a display unit  104 . Moreover, the memory  102  also temporally stores data (such as still image data obtained from the image capture unit  101  or the storage medium  111  and the corresponding additional data) to be written in the PC  20  and data (such as set data used in an image process unit  103 ) read from the PC  20 . Furthermore, the memory  102  can be used as a working area of a control unit  106 . 
   A function of the image process unit  103  is to generate reduced image data from the still image data temporally stored in memory  102 . Another function of the image process unit  103  is to tune at least one of the image quality, white balance, color balance, brightness, and sharpness of the still image data temporally stored in memory  102  in accordance with one of a plurality of set data stored in a memory  1061  of the control unit  106 . Still another function of the image process unit  103  is to encode or decode the still image data temporally stored in memory  102  in accordance with a predetermined encoding or decoding system. 
   The display unit  104  is means for displaying display data, such as reduced image data of still image data picked up by the image capture unit  101  or read from the storage medium  111 , or menu-panel data for illustrating a menu-panel. 
   A DIU (digital interface unit)  105  is digital communication means for controlling digital communications between the digital camera  10  and external units including the PC  20 . The DIU  105  reads data requested by the PC  20  from the memory  102  and writes it in the PC  20 . The DIU  105  is in conformity with at least one of a wire communication system, a wireless communication system, and an optical communication system. Accordingly, for example, the DIU  105  may be in conformity with standards about serial buses (such as USB (Universal Serial Bus) 1.1 or USB 2.0 in IEEE Std 1394-1995). In the present embodiment, for example, the DIU  105  is in conformity with IEEE Std 1394-1995 and its related standards. In addition, the DIU  105  supports the SBP-2 standard defined by ISO/IEC 14776-232. 
   The control unit  106  is means for controlling the functions provided in the digital camera  10 . In particular, a function of the control unit  106  is to change a data transfer mode between the memory  102  and the DIU  105 . Another function of the control unit  106  is to control PIO (programmed I/O) transfer between the memory  102  and the DIU  105 , and this function works effectively when the memory  102  and the DIU  105  are mutually in a low-speed transfer mode. In the low-speed transfer mode, the control unit  106  transfers data to be written in the PC  20  from the memory  102  to the DIU  105  by DMA (direct memory access) transfer or transfers {an item of} data read from the PC  20  from the DIU  105  to the memory  102  by DMA transfer. Memory  1061  is storage means for storing a control program executable in the control unit  106 . Memory  1061  also stores programs for controlling a process procedure, shown in  FIG. 3 , and the PIO transfer between the memory  102  and the DIU  105 . 
   A DMA controller A  107  is means for controlling the DMA transfer between the memory  102  and the display unit  104  and is activated when display data is displayed on the display unit  104 . 
   A DMA controller B  108  is means for controlling the DMA transfer between the memory  102  and the DIU  105  and is effective when the memory  102  and the DIU  105  are mutually in a high-speed transfer mode. In the high-speed transfer mode, the DMA controller B  108  transfers data to be written in the PC  20  from the memory  102  to the DIU  105  at high-speed by DMA transfer, or data read from the PC  20  from the DIU  105  to the memory  102  at high-speed by DMA transfer. 
   The operation unit  109  is means for inputting instructions of an operator. The operation unit  109  has manual operation buttons, such as a power switch for turning on or off the electric power of the digital camera  10 , a shutter release button for instructing the generation of still image data, a drive mode button for selecting one of the plurality of drive modes (such as the single-frame capture mode and the continuous capture mode), a photometric mode button for selecting one of the plurality of photometric modes, a menu-button for calling up menu-panel data to the display unit  104 , and a display button for displaying reduced image data of predetermined still image data on the display unit  104 . 
   A storage interface unit  110  has two functions for writing still image data read from the memory  102  and the corresponding additional data in the storage medium  111 , and for reading still image data selected by the control unit  106  and the corresponding additional data from the storage medium  111 . The still image data read from the storage medium  111  and the corresponding additional data are temporally stored in memory  102 . The storage medium  111  is removable. 
   Referring now to  FIG. 3 , an example of the process procedure for controlling the transfer mode between the memory  102  and the DIU  105  in accordance with an operating state of the digital camera  10  will be described. Whenever the digital camera  10  (target) receives a request from the PC  20  (initiator), the request is executed in accordance with the process procedure shown in  FIG. 3 . 
   In Step S 301 , the control unit  106  of the digital camera  10  (target) determines whether the request received from the PC  20  (initiator) is a command block ORB. If YES, a process in Step S 302  starts. 
   In Step S 302 , the control unit  106  checks the command type written in the command block field of the command block ORB received from the PC  20 . If the request is a command block ORB including the READ ( 10 ) command or the WRITE ( 10 ) command, a process in Step S 303  starts. 
   In Step S 303 , the control unit  106  determines whether the digital camera  10  is in the continuous capture mode. If YES, a process in Step S 304  starts. If NO, a process in Step S 305  starts. 
   In Step S 304 , the control unit  106  determines whether the digital camera  10  is in continuous capture processing (in particular, in photometric control processing or in image processing). A plurality of frames of still image data and corresponding additional data are generated at specified time intervals by the foregoing continuous capture processing, which includes the photometric control processing and image processing. Photometric processing of the image capture unit  101  is controlled by the foregoing photometric control processing in accordance with one of the plurality of photometric modes. Also, at least one of the image quality, white balance, color balance, brightness, and sharpness of the still image data temporally stored in memory  102  is tuned by the foregoing image processing in accordance with one of the set data stored in the memory  1061 . If YES, a process in Step S 306  starts in order to prevent occurrence of a continuous capture processing problem (for example, a delay in the photometric control processing or in the image processing). If NO, a process in Step S 305  starts. 
   In Step S 305 , the control unit  106  determines whether the digital camera  10  is in display processing. Display data, such as reduced image data of still image data picked up by the image capture unit  101  or read from the storage medium  111 , or menu-panel data for illustrating a menu panel, is displayed on the display unit  104  by the foregoing display processing. If YES, a process in Step S 306  starts in order to prevent occurrence of a display processing problem (for example, a delay in the display processing). If NO, a process in Step S 307  starts in order to execute a high-speed data transfer. 
   In Step S 306 , the control unit  106  changes the transfer mode between the memory  102  and the DIU  105  to the low-speed transfer mode (also referred to as PIO transfer mode). Once the transfer mode has been changed to the low-speed transfer mode, data transfer between the memory  102  and the DIU  105  is appropriately controlled by the control unit  106  so as to prevent occurrence of a display processing problem and a continuous capture processing problem. As a result, data (such as still image data obtained from the image capture unit  101  or the storage medium  111  and the corresponding additional data) requested by the command block ORB including the READ ( 10 ) command are transferred at low speed by the PIO transfer from the memory  102  to the DIU  105 , and are then written in the PC  20 . Also, data (such as the set data used in the image process unit  103 ) requested by the command block ORB including the WRITE ( 10 ) command is read from the PC  20  and is then transferred at low speed by the PIO transfer from the DIU  105  to the memory  102 . 
   In Step S 307 , the control unit  106  changes the transfer mode between the memory  102  and the DIU  105  to the high-speed transfer mode (also referred to as DMA transfer mode). Once the transfer mode has been changed to the high-speed transfer mode, data transfer between the memory  102  and the DIU  105  is controlled by the DMA controller B  108 . As a result, data (such as still image data obtained from the image capture unit  101 , or the storage medium  111 , and the corresponding additional data) requested by the command block ORB including the READ ( 10 ) command is transferred at high speed by DMA transfer from the memory  102  to the DIU  105 , and is then written in the PC  20 . Also, data (such as the set data used in the image process unit  103 ) requested by the command block ORB including the WRITE ( 10 ) command is read from the PC  20 , and is then transferred at high speed by DMA transfer from the DIU  105  to the memory  102 . 
   As described above, with the digital camera  10  according to the present embodiment, since the transfer mode between the memory  102  and the DIU  105  can be changed between a low-speed transfer mode and a high-speed transfer mode in accordance with the operating state of the digital camera  10 , data requested by a command block ORB including the READ ( 10 ) command or the WRITE ( 10 ) command is respectively written in or read from the PC  20 , without causing a display processing problem. 
   Also, with the digital camera  10  according to the present embodiment, since the transfer mode between the memory  102  and the DIU  105  can be changed between the low-speed transfer mode and the high-speed transfer mode in accordance with the operating state of the digital camera  10 , data requested by a command block ORB including the READ ( 10 ) command or the WRITE ( 10 ) command is respectively written in or read from the PC  20 , without causing a continuous capture processing problem (in particular, a photometric control processing problem and an image processing problem). 
   In addition, with the digital camera  10  according to the present embodiment, when the digital camera  10  is neither in display processing nor in the continuous capture processing, data transfer between the memory  102  and the DIU  105  can be executed at high speed, thereby improving the process speed of the image capture system. 
   The above-described preferred embodiment is merely exemplary of the present invention and should not be construed to limit the scope of the present invention. 
   The scope of the present invention is defined by the scope of the appended claims, and is not limited to only the specific descriptions in this specification. Furthermore, all modifications and changes belonging to equivalents of the claims are considered to fall within the scope of the present invention.