Patent Publication Number: US-7595901-B2

Title: Imaging apparatus, system having imaging apparatus and printing apparatus, and control method therefor

Description:
This application is a divisional of U.S. application Ser. No. 10/281,181, filed Oct. 28, 2002 now U.S. Pat. No. 7,161,701, allowed. 

   FIELD OF THE INVENTION 
   The present invention relates to an imaging apparatus such as a digital camera, a system having the imaging apparatus and a printing apparatus, and a control method therefor. 
   BACKGROUND OF THE INVENTION 
   In recent years, digital cameras (imaging apparatuses, imaging device or image sensing apparatus) capable of photographing an image by a simple operation and converting the image into digital image data have widely been used. To print an image photographed by this camera and use the print as a photograph, the photographed digital image data is temporarily input from the digital camera to a PC (computer), and undergoes image processing by the PC. The processed data is then output from the PC to a color printer, which prints the data. 
   To the contrary, there have been developed color print systems capable of directly transferring digital image data from a digital camera to a color printer and printing the data without the mediacy of any PC, and so-called photo-direct (PD) printers capable of directly mounting in a color printer a memory card which is mounted in a digital camera and stores a sensed image, and printing the photographed image stored in the memory card. 
   A digital camera generally stores image data encoded by JPEG or the like. In particular, to directly transfer image data from a digital camera to a printer and print the image data, JPEG-encoded data is temporarily decoded in printing. Then, the data is transferred to the printer and printed. Recently, printer apparatuses with a decoding function for JPEG codes and a function for color conversion and the like have been developed. To output print data to such a printer apparatus, the function of the connected printer apparatus must be confirmed to switch the format of output image data. 
   Digital cameras require decreases in size and weight. However, a plurality of keys for various operations in printing make the camera itself bulky, which conflicts with the user&#39;s needs. 
   SUMMARY OF THE INVENTION 
   The present invention has been made in consideration of the above situation, and has as its object to provide an imaging apparatus which, when connected to a printing apparatus, determines the type of printing apparatus and outputs corresponding image data, a system having the imaging apparatus and printing apparatus, and a control method therefor. 
   It is another object of the present invention to provide an imaging apparatus capable of, when connection to a printing apparatus is detected, automatically adding a user interface menu for outputting image data to the printing apparatus, a system having the imaging apparatus and printing apparatus, and a control method therefor. 
   Other features and advantages of the present invention will be apparent from the following descriptions taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the descriptions, serve to explain the principle of the invention. 
       FIG. 1  depicts a schematic perspective view showing a photo-direct printer apparatus according to an embodiment of the present invention; 
       FIG. 2  depicts a schematic view showing the operation panel of the photo-direct printer apparatus according to the embodiment; 
       FIG. 3  is a block diagram showing the arrangement of the main part concerning control of the photo-direct printer apparatus according to the embodiment; 
       FIG. 4  is a block diagram showing the arrangement of the ASIC of the photo-direct printer apparatus according to the embodiment; 
       FIG. 5  depicts a view for explaining connection between the photo-direct printer apparatus and a digital camera according to the embodiment; 
       FIG. 6  depicts a view showing a display example on the display of the operation panel when the photo-direct printer apparatus and digital camera according to the embodiment are connected; 
       FIG. 7  is a flow chart for explaining an initial state when the PD printer apparatus and digital camera according to the embodiment are connected; 
       FIG. 8  depicts a signal sequence chart for explaining exchange of signals in initial operation when the PD printer apparatus and digital camera according to the embodiment are connected; 
       FIG. 9  depicts a schematic view showing the appearance of the operation unit of the digital camera according to the embodiment; 
       FIG. 10  is a block diagram showing the arrangement of the digital camera according to the embodiment; 
       FIG. 11  is a flow chart for explaining an operation when print operation starts in the digital camera while the PD printer apparatus and digital camera according to the embodiment are connected; 
       FIG. 12  depicts a signal sequence chart for explaining exchange of signals when the PD printer apparatus and digital camera according to the embodiment are connected and perform normal image printing; 
       FIG. 13  is a flow chart for explaining coefficient processing of the number of prints in the digital camera according to the embodiment; 
       FIG. 14  is a flow chart for explaining print processing operation executed in the printer apparatus while the PD printer apparatus and digital camera according to the embodiment are connected; 
       FIG. 15  is a flow chart for explaining normal print operation executed in the printer apparatus while the PD printer apparatus and digital camera according to the embodiment are connected; 
       FIG. 16  depicts a signal sequence chart for explaining exchange of signals in trimming and/or date printing when the PD printer apparatus and digital camera according to the embodiment are connected and perform image printing; 
       FIG. 17  is a flow chart for explaining index print operation executed in the printer apparatus while the PD printer apparatus and digital camera according to the embodiment are connected; 
       FIG. 18  depicts a signal sequence chart for explaining exchange of signals in index printing when the PD printer apparatus and digital camera according to the embodiment are connected and perform image printing; 
       FIG. 19  is a flow chart for explaining layout print operation executed in the printer apparatus while the PD printer apparatus and digital camera according to the embodiment are connected; 
       FIG. 20  is a flow chart for explaining an operation when an error occurs in the printer apparatus during print processing in the printer apparatus while the PD printer apparatus and digital camera according to the embodiment are connected; 
       FIG. 21  depicts a signal sequence chart for explaining exchange of signals when an error occurs in the printer apparatus during print processing in the printer apparatus while the PD printer apparatus and digital camera according to the embodiment are connected and perform image printing; 
       FIG. 22  depicts a signal sequence chart for explaining exchange of signals when the camera issues forced termination of printing during print processing in the printer apparatus while the PD printer apparatus and digital camera according to the embodiment are connected and perform image printing; and 
       FIG. 23  depicts a signal sequence chart for explaining exchange of signals when an error occurs in the printer apparatus during print processing in the printer apparatus and the camera issues forced restart of printing with respect to the error while the PD printer apparatus and digital camera according to the embodiment are connected and perform image printing. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. 
     FIG. 1  is a schematic perspective view showing a photo-direct printer  1000  according to the embodiment of the present invention. The photo-direct printer  1000  has a general PC printer function of receiving data from a host computer (PC) and printing the data, and a function of directly reading and printing image data stored in a storage medium such as a memory card, or receiving image data from a digital camera connected to the printer apparatus and printing the data. 
   In  FIG. 1 , the main body which defines the casing of the photo-direct printer  1000  according to this embodiment has casing members: a lower case  1001 , upper case  1002 , access cover  1003 , and discharge tray  1004 . The lower case  1001  forms almost the lower half of the printer  1000 , whereas the upper case  1002  forms almost the upper half of the main body. A combination of these cases forms a hollow structure with a storage space where each mechanism (to be described later) is accommodated. The upper and front surfaces have openings. The discharge tray  1004  is rotatably held at one end by the lower case  1001 , and the opening in the front surface of the lower case  1001  is opened/closed by rotating the discharge tray  1004 . To execute a print operation, the discharge tray  1004  is rotated toward the front side to open the opening. Print sheets can be discharged from the opening, and the discharged print sheets can be sequentially stacked. The discharge tray  1004  houses two auxiliary trays  1004   a  and  1004   b . These trays are selectively pulled out to enlarge/reduce the paper support area in three stages, as needed. 
   The access cover  1003  is rotatably held at one end by the upper case  1002  so as to open/close the opening formed in the upper surface. Opening the access cover  1003  enables exchanging a print head cartridge (not shown), ink tank (not shown), or the like accommodated in the main body. Although not shown, a projection formed on the back surface of the access cover  1003  rotates a cover opening/closing lever when the access cover  1003  is opened/closed. The lever rotation position is detected by a microswitch or the like, thereby detecting the open/closed state of the access cover  1003 . 
   A power switch  1005  is provided with the upper surface of the upper case  1002 . An operation panel  1010  having a liquid crystal display  1006 , various key switches, and the like is arranged on the right side of the upper case  1002 . The structure of the operation panel  1010  will be described in detail with reference to  FIG. 2 . Reference numeral  1007  denotes an automatic feeder which automatically feeds print sheets into the apparatus main body; numeral  1008  denotes a paper interval selection lever for adjusting the interval between the print head and the print sheet; and numeral  1009  denotes a card slot into which an adapter capable of mounting a memory card is inserted. Image data stored in a memory card can be directly received and printed via the adapter. The memory card (PC) includes, e.g., a compact flash memory™, smart media, or memory stick. Reference numeral  1011  denotes a viewer (liquid crystal display) which is detachable from the apparatus main body and is used to display an image of one frame, an index image, and the like when images stored in the PC card are searched for an image to be printed; and numeral  1012  denotes a terminal (input terminal for inputting image data) for connecting a digital camera (to be described later). A USB bus connector  1013  in  FIG. 3  for connecting a personal computer (PC) is provided with the back side of the apparatus main body. 
     FIG. 2  is a schematic view showing the operation panel  1010  according to this embodiment. 
   In  FIG. 2 , the liquid crystal display  1006  displays menu items for various settings of data on items printed on the right and left of the display  1006 . The displayed items are the first photograph number of a print range, a designated frame number (start/designate), the last photograph number of the print range (end), the number of prints (number of copies), the type of paper (print sheet) used for printing (paper type), setting of the number of photographs to be printed on one sheet (layout), designation of the print quality (quality), designation whether to print a photographing date (date printing), designation whether to correct and print a photograph (image correction), and display of the number of sheets necessary for printing (number of sheets). These items are selected or designated with cursor keys  2001 . Reference numeral  2002  denotes a mode key which allows switching the type of printing (index printing, printing of all frames, printing of one frame, or the like) every time the key is pressed; numeral  2004  denotes a maintenance key for performing printer maintenance such as cleaning of the printer head; numeral  2005  denotes a print start key which is pressed to designate the start of printing or establish maintenance setting; and numeral  2006  denotes a stop key which is pressed to stop printing or designate to stop a maintenance processing. 
   The arrangement of the main part concerning control of the photo-direct printer apparatus according to this embodiment will be explained with reference to  FIG. 3 . In  FIG. 3 , the same reference numerals as in the foregoing drawings denote the same parts, and a description thereof will be omitted. 
   In  FIG. 3 , reference numeral  3000  denotes a controller (control board); numeral  3001  denotes an ASIC (application specific LSI) whose arrangement will be described in detail below with reference to the block diagram of  FIG. 4 ; numeral  3002  denotes a DSP (Digital Signal Processor) which incorporates a CPU and performs various control processes (to be described later), and image processes such as conversion from an RGB signal (RGB signal indicates three primary color signals for display and is called as a luminance signal) to a CMYK signal (CMY signal indicates three primary color signal for printing and a CMYK signal including a black signal is called as a density signal), scaling, gamma conversion, and error diffusion; numeral  3003  denotes a memory having a program memory  3003   a  which stores the control program of the CPU of the DSP  3002 , a RAM area which stores variables and the like in executing a program, and a memory area functioning as a work memory which stores image data and various data; numeral  3004  denotes a printer engine which is an ink-jet print type printer engine for printing a color image by using a plurality of color inks in this embodiment; numeral  3005  denotes a connector serving as a port for connecting a digital camera  3012 ; numeral  3006  denotes a connector for connecting the viewer  1011 ; and numeral  3008  denotes a USB bus hub which transmits data from a PC  3010  and outputs the data to the printer engine  3004  via a USB bus  3021  when the printer  1000  performs printing based on image data from the PC  3010 . The connected PC  3010  can directly exchange data and signals with the printer engine  3004  and execute printing (functions as a general PC printer). Reference numeral  3009  denotes a power connector which receives from a power supply  3013  a DC voltage converted from a commercial AC voltage. The PC  3010  is a general personal computer. Reference numeral  3011  denotes a memory card (PC card) described above; and numeral  3012  denotes the digital camera. 
   Signal exchange between the controller  3000  and the printer engine  3004  is performed via the USB bus  3021  or an IEEE 1284 bus  3022 . 
     FIG. 4  is a block diagram mainly showing the arrangement of the ASIC  3001 . Also in  FIG. 4 , the same reference numerals as in the foregoing drawings denote the same parts, and a description thereof will be omitted. 
   Reference numeral  4001  denotes a PC card interface which reads image data stored in the mounted PC card  3011  or writes data in the PC card  3011 ; and numeral  4002  denotes an IEEE 1284 interface which exchanges data with the printer engine  3004 . The IEEE 1284 interface is a bus used to print image data stored in the digital camera  3012  or PC card  3011 . Reference numeral  4003  denotes a USB interface which exchanges data with the PC  3010 ; numeral  4004  denotes a USB host interface which exchanges data with the digital camera  3012 ; numeral  4005  denotes an operation panel interface which receives various operation signals from the operation panel  1010  or outputs display data to the display  1006 ; numeral  4006  denotes a viewer interface which controls display of image data on the viewer  1011 ; numeral  4007  denotes an interface which controls an interface between various switches, an LED  4009 , and the like; numeral  4008  denotes a CPU interface which controls data exchange between these interfaces and the DSP  3002 ; and numeral  4010  denotes an internal bus (ASIC bus) which is connected to these units. 
   The outline of the operation based on the above arrangement will be described. 
   &lt;General PC Printer Mode&gt; 
   The general PC printer mode is a print mode in which an image is printed on the basis of print data from the PC  3010 . 
   In this PC printer mode, when data from the PC  3010  is input via the USB bus connector  1013 , the data is directly sent to the printer engine  3004  via the USB bus hub  3008  and USB bus  3021  ( FIG. 3 ). Printing is executed based on the data from the PC  3010 . 
   &lt;Direct Print Mode from PC Card&gt; 
   When the PC card  3011  is mounted/dismounted in/from the card slot  1009 , an interrupt occurs, and the DSP  3002  can detect mounting/dismounting (removal) of the PC card  3011 . If the PC card  3011  is mounted, image data which is compressed (e.g., JPEG-compressed) and stored in the PC card  3011  is read out and stored in the memory  3003 . The compressed image data is decompressed and stored in the memory  3003  again. If printing of the stored image data is designated on the operation panel  1010 , conversion from an RGB signal to a YMCK signal, gamma correction, error diffusion, and the like are executed to convert the data into print data printable by the printer engine  3004 . The resultant data is output to the printer engine  3004  via the IEEE 1284 interface  4002  to print the data. 
   &lt;Direct Print Mode from Camera&gt; 
     FIG. 5  is a view for explaining connection between the photo-direct printer  1000  and the digital camera  3012  according to this embodiment. 
   In  FIG. 5 , a cable  5000  comprises a connector  5001  connected to the connector  1012  of the printer  1000 , and a connector  5002  connected to a connector  5003  of the digital camera  3012 . The digital camera  3012  can output via the connector  5003  image data saved in an internal memory. The digital camera  3012  can adopt various arrangements such as one incorporating a memory as a storage means and one having a slot for mounting a detachable memory. By connecting the printer  1000  and digital camera  3012  via the cable  5000  shown in  FIG. 5 , image data from the digital camera  3012  can be directly printed by the printer  1000 . 
     FIG. 6  depicts a view showing the display state of the display  1006  of the operation panel  1010  when the digital camera  3012  is connected to the printer  1000 . In this case, the display  1006  displays only a camera mark  6000 . The display and operation on the operation panel  1010  are invalidated, and image display on the viewer  1011  is also invalidated. As subsequent operation, only key operation on the digital camera  3012  and image display on the display (not shown) of the digital camera  3012  are valid. The user can designate printing by using the digital camera  3012 . 
   An operation when printing is done by connecting the PD printer  1000  and digital camera  3012  according to the embodiment will be explained in detail. 
     FIG. 7  is a flow chart showing connection processing to the PD printer  1000  in the digital camera  3012  according to the embodiment.  FIG. 8  depicts a view for explaining signal protocols between the digital camera  3012  and the PD printer  1000  in connection. 
   If it is detected in step S 1  that the digital camera  3012  has been connected to the PD printer  1000  via the USB bus cable  5000 , the flow advances to step S 2  to turn on the camera  3012 . Whether the USB bus has been connected is detected based on that the voltage level of a given signal on the USB bus reaches a predetermined voltage level. The process then advances to step S 3  and a Wake-up sequence is executed in the camera  3012 , in response to a Wake-up request  800  ( FIG. 8 ) from the PD printer  1000 . As shown by procedures in  FIG. 8 , when the digital camera  3012  receives commands such as a GetDeviceIDData command, SetNegotiationData, and Query from the PD printer  1000 , the camera  3012  acquires information necessary to exchange data and an ID representing the type of the digital camera  3012 . 
   The process advances to step S 4  and the type of the connected PD printer  1000  is set to a predetermined type (default value: Printertype=0). The process proceeds to step S 5  and it is checked whether a printer ID (PrinterID) from the PD printer  1000  has been received. If the ID of the PD printer  1000  is received by SetPrinterID  801  in  FIG. 8 , the process proceeds to step S 6  and the received PrinterID is stored into a memory (not shown) of the camera  3012 . Accordingly, the type of the connected PD printer  1000  is determined. After that, the digital camera  3012  receives a BatteryCheck command from the PD printer  1000 , and sends back a response to this command. In step S 7 , it is checked whether a command (PrinterModeInit)  802  ( FIG. 8 ) representing the end of printer mode setting processing is received from the PD printer  1000 . If NO in step S 7 , the process proceeds to step S 5  and the above-described processing is executed; if YES in step S 7 , the process advances to step S 8  and shifts to a print processing mode. 
   If the type of a printer is not identified, e.g., an unknown printer ID is received, then a predetermined type of the printer may be set or a user can manually set the type. This can prevent there from being non-operability by an error. 
   In  FIG. 8 , if the PD printer  1000  detects connection with the digital camera  3012 , the PD printer  1000  transmits to the digital camera  3012  a request defined by the USB bus and various requests according to the embodiment. The camera  3012  sends back a “response” to the requests, thereby executing signal exchange, as shown in  FIG. 8 . 
     FIG. 9  depicts a view for explaining an operation of the digital camera  3012  when the digital camera  3012  and PD printer  1000  according to the embodiment are connected via the cable  5000 . 
     FIG. 9  shows the back surface of the digital camera  3012 . Reference numeral  90  denotes a playback button which designates to play back an image which has been sensed and stored; numeral  91  denotes a liquid crystal display which displays an image, menu, and the like; numeral  92  denotes a print menu; and numeral  93  denotes a viewfinder. Designation of a print image in the digital camera  3012  is basically the same as an operation of creating a DPOF file when developing (printing) of sensed images is ordered for a Photo print shop. More specifically, printing of images can be ordered by pressing the playback button  90  and designating printing of recorded images one by one or whole of recorded images. When the digital camera  3012  is connected to the PD printer  1000 , the print menu  92  is displayed on the liquid crystal display  91 , and image selection and printing designation are done by using the menu. By selecting the print menu  92 , a printing paper size, color/monochrome printing, the type of paper (plain paper, fine paper, or the like) used for printing, unframed/framed printing and the like, can be designated. Also, index printing, date printing, trimming printing, layout printing and the like can be designated. 
     FIG. 10  is a block diagram showing a typical arrangement of the DSC  3012  according to the embodiment of the present invention. Some digital cameras connectable to the PD printer  1000  of the embodiment may not have any display  91  to be described later. 
   In  FIG. 10 , reference numeral  3100  denotes a CPU which controls the overall DSC; numeral  3101  denotes a ROM which stores a program for describing a processing procedures implemented by the CPU  3100 ; numeral  3102  denotes a RAM used as the work area of the CPU  3100 ; and numeral  3103  denotes switches for various operations that include various switches including the above-described switches, cursor keys, and the like. The liquid crystal display  91  is used to confirm a sensed image and display menus for various settings. Reference numeral  3105  denotes an optical unit mainly constituted by a lens and its driving system; numeral  3106  denotes a CCD element; numeral  3107  denotes a driver which drives and controls the optical unit  3105  under the control of the CPU  3100 ; numeral  3108  denotes a connector for connecting a storage medium  3109  (compact flash® memory card, smart medium, or the like); and  3110 , a USB interface (USB slave side) for connecting a PC or the PD printer  1000  of the embodiment. 
   This embodiment will mainly exemplify printing performed by connecting the PD printer  1000  and DSC  3012  described above. The purpose of this embodiment is to provide a PD printer apparatus capable of connecting a digital camera of each manufacturer and devices (DSPD: Digital Still Photography Devices) such as a cell phone and memory device to an image output apparatus such as the PD printer  1000 , and printing an image based on image data acquired from the connected device. 
     FIG. 11  is a flow chart showing processing in the camera  3012  activated by a designation of the start of printing by the digital camera  3012 . A program which executes this processing is stored in the ROM  3101 .  FIG. 12  depicts a view for explaining protocols when the PD printer  1000  performs a print processing in accordance with a print instruction from the digital camera  3012 . While the digital camera  3012  and PD printer  1000  are connected, an operation on the operation panel  1010  of the PD printer  1000  becomes invalid, and an operation with the operation button  3013  of the digital camera  3012  becomes valid. The user operates the button of the camera  3012  to select images to be printed, and designates to print the selected images. Then, a print request is issued from the camera  3012  to the PD printer  1000 , thereby the printer  1000  prints the images. 
   In step S 11 , it is checked whether a print instruction has been input by manipulating the operation button  3013  of the digital camera  3012 . If YES in step S 11 , the process advances to step S 12  and the type of connected printer is determined. This determination is achieved based on a printer ID set in step S 6  in the flow chart of  FIG. 7 . If the type of the printer is not determined based on the printer ID, a user may set the type. If the PD printer  1000  according to the embodiment has been connected to the camera  3012 , the process advances to step S 13 , information about an image file to be printed is set in a PrintRequest parameter, and the PrintRequest is transmitted to the printer  1000  ( 900  in  FIG. 12 ). Then a file request command (Open/Close/Read/SeekFile) is received from the PD printer  1000  ( 901  in  FIG. 12 ) (step S 15 ). In response to this, the image file to be printed is sent to the printer  1000  (step S 16 ). If the image file to be printed is a JPEG file, the JPEG file is transmitted without decoding any JPEG code. This is because the PD printer  1000  according to the embodiment comprises the JPEG decoding function and an image processing function, as described above. The process advances to step S 17 , and upon reception of EndPrint from the PD printer  1000 , it is checked whether all image files have been transmitted. If NO in step S 17 , the process returns to step S 13  and the above-mentioned processing is repeated; if YES, advances to step S 18  and a command (PrintRequest (NULL)) in which all PrintRequest parameters are set to “0” ( 903  in  FIG. 12 ), is transmitted to the PD printer  1000 . After that, a sign representing “during printing” of the digital camera  3012  is disappeared, and the print mode is terminated. In step S 19 , it waits until it receives EndPrint representing the end of print processing from the PD printer  1000  ( 904  in  FIG. 12 ). After that, the digital camera  3012  terminates the print processing. Because of normal print processing, the PD printer  1000  prints image data transmitted in response to a file request command (Open/Close/Read/SeekFile) every time the PD printer  1000  receives the image data. Even if the PD printer  1000  receives a finally transmitted command (PrintRequest (NULL)) in which all parameters are set to “0”, the printer  1000  does not start printing. 
   If the type of connected printer is determined in step S 12  to be one other than the PD printer  1000  according to the embodiment, e.g., to be an apparatus having no JPEG code decoding function, color conversion processing function, or the like, the process proceeds to step S 20 . The digital camera  3012  decodes a stored JPEG file, changes the image size to a paper size used for printing, and executes sharpness/color conversion and the like. In step S 21 , the digital camera  3012  has converted the image file into bitmap image data as print image data, and transmits the bitmap image data to the printer apparatus. 
   In this embodiment, after the process advanced to step S 20 , the digital camera  3012  has completed decoding, change of the image size, sharpness/color conversion and the like to generate bitmap image data as print data, until the digital camera  3012  detects a timing at which the connected printer apparatus has prepared for predetermined printing and the image data to be printed is transmitted. This shortens the total print processing time. Detection of the timing at which the image data is transmitted is based on reception of an instruction from the connected printer. 
   In this manner, the digital camera  3012  according to the embodiment checks the type of connected printer when the start of printing is designated. In correspondence with the type of the connected printer, the digital camera  3012  determines whether an image file to be transmitted to the printer is kept JPEG-encoded or a bit-map image data obtained by decoding the JPEG code of the image file. In this way, the digital camera  3012  can transmit the image data (print data) corresponding to the type of the connected printer. 
     FIG. 13  is a flow chart for explaining the count display of the number of prints in the digital camera  3012 . 
   In step S 31 , both a variable (current) representing a counted number of images and a variable (page) representing a counted number of prints are set to “1”, and the maximum number of images to be printed on one sheet is set in a variable (total). These variables are stored in the RAM  3102  of the camera  3012 . The process advances to step S 32  and it is checked whether the variable (current) value is equal to or larger than the variable (total) value. If YES in step S 32 , the process proceeds to step S 33 , the variable (current) is initialized to “0”, and the number (page) of prints is incremented by one, and the result is displayed on the liquid crystal display  91  of the digital camera  3012 . If NO in step S 32 , the process proceeds to step S 34  and it waits until EndPrint representing the end of printing one image is received from the printer apparatus. Upon reception of EndPrint, the process advances to step S 35  and it is checked whether all target image data have been printed. If NO in step S 35 , the process proceeds to step S 36 , the variable (current) count value representing a counted number of images is incremented by one, and the process returns to step S 32 . 
   If the number of sheets is counted up and displayed every time one image is printed upon printing a plurality of images on one sheet, like index printing or layout printing to be described later, the number of printed images does not coincide with the number of printed sheets. To prevent this, the number (page) of printed sheets is incremented by one when the variable (current) value (number of printed images) reaches the number (total) of images to be printed on one sheet. This makes that the number of printed images and the number of printed sheets become correct. 
   In this way, the digital camera  3012  as an imaging apparatus issues a print instruction, transfers an image file to be printed to the PD printer  1000  in response to a request from the PD printer  1000 , and receives EndPrint from the PD printer  1000  after the completion of the printing. The digital camera  3012  can display the number of printed images on the liquid crystal display  91 , on the basis of reception of EndPrint and the number of images to be printed on one sheet. 
   To print one image on one sheet, the PD printer  1000  sends an image file request corresponding to one image to the digital camera  3012 . In response to this request, the digital camera  3012  transmits a corresponding image file to the PD printer  1000 . The PD printer  1000  sends EndPrint to the digital camera  3012 , after the completion of printing based on the transferred image file. In this case, the number of printed images is counted and displayed every time EndPrint is received. If the total number of images to be printed is obtained in advance by one print instruction, the total number of images and the number of printed images are displayed, providing a high-convenience arrangement for an operator of the digital camera  3012 . 
   In the above example, the number of printed images is displayed. The order of an image being printed can also be displayed by subtracting a value “1” from the number of printed images. Further, the remaining number of images can be displayed by subtracting the number of printed images from the total number of images to be printed. 
   Print processing in the PD printer  1000  according to the embodiment will be explained. 
     FIG. 14  is a flow chart showing normal print processing (not including any index, layout, or date printing) of printing image data from the camera  3012  in the PD printer  1000  according to the embodiment. Exchange of signals between the PD printer  1000  and the digital camera  3012  in this case is the same as that shown in  FIG. 12 . 
   In step S 41 , it waits until PrintRequest (print request)  900  is received from the digital camera  3012 . Upon reception of PrintRequest, the process proceeds to step S 42  and it is checked whether all the parameters contained in PrintRequest are “0”. If NO in step S 42 , the process advances to step S 43  because PrintRequest is a print mode designation command. In step S 43 , it is checked whether index printing is designated. If YES in step S 43 , the process advances to step S 44  and an index print processing is executed. This processing will be described later with reference to the flow chart of  FIG. 17 . Parameters set in PrintRequest contain paper type determination codes (including a paper designation code, the presence/absence of the next image, index printing, the presence/absence of trimming, the presence/absence of the date, the presence/absence of unframed printing, and the like), the size of a designated file, and the file name. 
   If NO in step S 43 , the process proceeds to step S 45  and it is checked whether layout printing is designated. If YES in step S 45 , the process advances to step S 46  and a layout printing to be described later with reference to  FIG. 19  is implemented. If neither the index printing nor the layout printing is designated, the process advances to step S 47 , and a normal print processing of receiving and printing an image file is implemented. The normal print processing will also be described in detail later with reference to the flow chart of  FIG. 15 . 
   If all the PrintRequest parameters are “0” (print request) (PrintRequest (NULL)) in step S 42 , the process advances to step S 48  and it is checked whether a print mode for image data from the digital camera  3012  is designated. If YES in step S 48 , the process advances to step S 49  and it is checked whether the print data which has not been printed yet exists. If YES in step S 49 , the process advances to step S 50 , the unprinted data is printed. If NO in step S 49  or the print processing in step S 50  is terminated, the process advances to step S 51  and EndPrint representing the end of printing is transmitted to the digital camera  3012 . After the processes in steps S 44 , S 46 , S 47 , and S 51 , the process returns to step S 41  again and it waits for the next print request from the digital camera  3012 . 
   [Normal Printing] 
   Normal print processing in step S 47  of  FIG. 14  will be explained with reference to the flow chart of  FIG. 15  and the sequence chart of  FIG. 16 . 
   In  FIG. 15 , if the PD printer  1000  receives PrintRequest from the camera  3012  in step S 61  ( 1500  in  FIG. 16 ), it is checked whether a normal print mode other than index printing or layout printing is designated. If NO in step S 61 , the process ends. If YES in step S 61 , the process proceeds to step S 62  and it is checked whether trimming and/or date printing is designated. If NO in step S 62 , the process advances to step S 64 ; if YES, the process advances to step S 63 , GetAdditionalParam ( 1501 ) is transmitted to the digital camera  3012 , and a trimming position and/or date data is obtained from the camera  3012 . In step S 64  and subsequent steps, the PD printer  1000  executes print processing. 
   In step S 65 , the structure of an image file to be printed is obtained. The process advances to step S 66  and the print file name is obtained and an Open/Close/Read/SeekFile command is transmitted to the digital camera  3012  ( 1502  in  FIG. 16 ). In step S 67 , the file data from the camera  3012  is acquired, and decoding, change of the size, color conversion and the like are performed. The process advances to step S 68 , and the developed print data in a layout designated by the camera  3012  is obtained. The process advances to step S 69  and it is checked whether all image files to be printed have been acquired. If NO in step S 69 , the process returns to step S 65  and the above-described processing is executed. If YES in step S 69 , EndPrint is transmitted to the digital camera  3012  ( 1503 ). Thereafter, it is checked whether a print start instruction (PrintRequest (Null)) ( 1504  in  FIG. 16 ) is received from the digital camera  3012 . If PrintRequest has been received, the process advances to step S 70 , image data is developed into print data, and the print data is supplied to the printer engine  3004 , and then print processing is executed. In the print processing, the printer engine  3004  prints an image on a sheet on the basis of the received print data, and discharges the printed sheet. After printing ends, the process proceeds to step S 71 , EndPrint is transmitted to the camera  3012  ( 1505  in  FIG. 16 ), and the processing is terminated. 
     FIG. 16  depicts an exchange of data between the PD printer  1000  and the digital camera  3012  when trimming/date printing is performed upon printing an image. 
   If the first PrintRequest parameter ( 1500 ) designates trimming/date printing or the like, the PD printer  1000  transmits GetAdditionalParam ( 1501 ) to the digital camera  3012 , and requests detailed data. A response to GetAdditionalParam from the digital camera  3012  contains the origin coordinates (x,y) of the trimming range, the trimming range (horizontal width Δ x and vertical width Δ y), and a character string representing the date. In response to an Open/Close/Read/SeekFile command ( 1502 ) from the PD printer  1000 , the camera  3012  reads out corresponding image file, and transmits it as a JPEG code to the printer  1000 . 
   [Index Printing] 
     FIG. 17  is a flow chart showing index printing in the PD printer  1000  according to the embodiment. Index print processing is to print as a thumbnail image the index of an image stored in the digital camera  3012 .  FIG. 18  depicts a protocol view for explaining exchange of signals in executing index print processing. 
   In step S 81 , the PD printer  1000  receives PrintRequest from the digital camera  3012  ( 1700  in  FIG. 18 ), and checks whether this PrintRequest is the first PrintRequest designating index printing. If YES in step S 81 , the process advances to step S 82  and an index print mode is set. The process then proceeds to step S 83 , the number of indices printable on a sheet subjected to printing is obtained, and the number of indices is transmitted to the digital camera  3012 . This corresponds to transmission of SetIndexNum in  1701  of  FIG. 19 . In step S 84 , it is checked whether index data based on PrintRequest has been received from the digital camera  3012 . If YES in step S 84 , the process proceeds to step S 85  and the number of indices is incremented by one. The process advances to step S 86  and it is checked whether the number of received indices has reached the number of indices printable on one sheet. If NO in step S 86 , the process returns to step S 84  and the above-described processing is repeated. 
   If YES in step S 86 , PrintRequest (NULL) (all parameters are 0) is received from the digital camera  3012  ( 1702 ). The process then advances to step S 87  and print processing is implemented as in step S 64  and subsequent steps in the flow chart of  FIG. 15 . In this case, Open/Close/Read/SeekFile from the printer  1000  designates the address of a JPEG code where the index data of the image file is stored. The image file is read out from the designated address in the digital camera  3012  and transmitted to the printer  1000 . Index printing can, therefore, be easily performed. After printing on one sheet ends, the process advances to step S 88  and all printed index data are erased. The process advances to step S 89 , and EndPrint is transmitted to the digital camera  3012 , thereby the printer  1000  notifies the digital camera  3012  of the end of index printing on one sheet. The process advances to step S 90  and it is checked whether print processing of all indices has ended. If NO in step S 90 , the process returns to step S 81 . 
   If the PrintRequest parameter does not designate index printing in step S 84 , the process proceeds to step S 91  and it is checked whether the PrintRequest is PrintRequest (NULL) in which all parameters are “0”. If YES in step S 91 , this PrintRequest is a print instruction from the digital camera  3012 . The process advances to step S 87  and print processing is executed as in step  64  and subsequent steps in the flow chart of  FIG. 15 . This print instruction designates the re-start of index printing when the number of indices has not reached the maximum number of indices printable on one sheet. If NO in step S 91 , the process advances to step S 89  and the printer  1000  responds to the camera  3012  by EndPrint. [Layout printing]  FIG. 19  is a flow chart showing a layout print processing in the PD printer  1000  according to the embodiment. The layout print processing is to lay out on one sheet a plurality of images stored in the camera  3012  and print the images. 
   In step S 101 , the PD printer  1000  receives PrintRequest designating layout printing from the digital camera  3012 , and it is checked whether this PrintRequest is the first PrintRequest. If YES in step S 101 , the process advances to step S 102  and a layout print mode is set. The process advances to step S 104  and it is checked whether trimming and/or date printing is designated. If NO in step S 104 , the process advances to step S 106 ; if YES, the process advances to step S 105  and trimming and/or date data is obtained. This is achieved by GetAdditionalParam in  1501  of  FIG. 16 . 
   The process then advances to step S 106  and image data is saved. The process advances to step S 107  and it is checked whether all image data to be printed on one sheet have been saved. If YES in step S 107 , the process advances to step S 108  and print processing is executed as in step S 64  and subsequent steps in the flow chart of  FIG. 15 . After layout printing on one sheet ends, the process proceeds to step S 109  and printed image data is cleared. The process advances to step S 110 , and EndPrint is transmitted to the digital camera  3012 , thereby the printer  1000  notifies the camera  3012  of the end of layout printing on one sheet. The process advances to step S 111  and it is checked whether layout print processing has ended. If NO in step  5111 , the process returns to step  5101 . 
   If the mode is the same as the first layout print mode in step S 103 , the process advances to step S 104  and the above-described processing is executed. If NO in step S 103 , the PD printer  1000  ends print processing. 
   If NO in step S 107 , the process advances to step S 112  and it is checked whether the PrintRequest is PrintRequest (NULL) (print request) in which all parameters are “0”. If YES in step S 112 , this PrintRequest is a print instruction from the camera  3012 . The process proceeds to step S 108  and the above-described print processing is executed. This print instruction designates the start of printing when the number of laid out images has not reached the maximum number of images to be laid out on one sheet. If NO in step S 112 , the process proceeds to step S 110  and the printer  1000  responds to the digital camera  3012  by EndPrint. 
   [Printer Error Processing] FIG. 20  is a flow chart showing processing when an error occurs in the PD printer  1000  according to the embodiment.  FIG. 21  is a sequence chart for explaining exchange of signals in this case. 
   In step S 121 , if any error occurs in the printer  1000 , the printer  1000  transmits, to the camera  3012 , PrintDisable representing printing cannot be continued ( 1900  in  FIG. 21 ). This PrintDisable notifies the digital camera  3012  of the type of generated error. The flow advances to step S 122  to check whether a print stop/restart instruction has been issued. If NO in step S 122 , the process advances to step S 123  to check whether the error in the printer  1000  has been canceled. If YES in step S 123 , the process advances to step S 124  to notify the camera  3012  of the cancellation of the error ( 1901  in  FIG. 21 ). Then, the process advances to step S 125  to check whether another error has occurred. If YES in step S 125 , the process returns to step S 121 ; if all errors have been canceled, the process advances to step S 126  to continuously execute the current print processing. 
   If the restart/stop of printing is designated by the camera  3012  in step S 122 , the process advances to step S 127 . For a print restart instruction, the process advances to step S 124  to notify the digital camera  3012  of the cancellation of the error. If the stop of printing is designated in step S 127 , the process advances to step S 128  to abort print processing and notify the camera  3012  of the cancellation of the error. 
     FIG. 22  depicts a sequence chart showing processing when the digital camera  3012  issues a forced print termination instruction during print processing in the PD printer  1000  according to the embodiment. 
   If the forced termination of print processing is designated by a forced termination instruction (PrintAbort) input from the digital camera  3012  during print processing  2111 , the printer  1000  aborts print processing in progress and transmits PrintDisable to the digital camera  3012  ( 2112 ). Upon reception of a response to PrintDisable from the digital camera  3012 , the printer  1000  completely cancels print operation, and transmits, to the digital camera  3012 , PrintEnable representing the possibility of accepting the next print instruction. 
     FIG. 23  depicts a sequence chart for explaining exchange of signals when print processing aborts due to generation of an error in the PD printer  1000  according to the embodiment and restarts in accordance with an instruction from the digital camera  3012 . 
   If any error occurs in the printer  1000  during print processing  2211 , the PD printer  1000  aborts print processing in progress and transmits PrintDisable to the digital camera  3012  ( 2212 ). The display on the display  91  of the camera  3012  changes from “during printing” to “error”. If the user determines that the error does not inhibit the continuation of printing, he/she designates “restart of printing” using the operation button  3103  of the digital camera  3012 . The digital camera  3012  transmits PrintRequest to the printer  1000  ( 2213 ). Upon reception of the print request signal, the printer  1000  transmits PrintEnable representing that printing is possible ( 2214 ). The PD printer  1000  issues a print file request, and the digital camera  3012  sends back image data in response to the request, thus restarting print processing  2215 . 
   The present invention may be applied to a system constituted by a plurality of devices (e.g., a host computer, interface device, reader, and printer) or an apparatus (e.g., a copying machine or facsimile apparatus) formed from a single device. 
   The object of the present invention is also achieved when a storage medium (or recording medium) which stores software program codes for realizing the functions (processes performed on the camera side and various print processes performed on the printer side) of the above-described embodiment is supplied to a system or apparatus, and the computer (or the CPU or MPU) of the system or apparatus reads out and executes the program codes stored in the storage medium. In this case, the program codes read out from the storage medium realize the functions of the above-described embodiment, and the storage medium which stores the program codes constitutes the present invention. The functions of the above-described embodiment are realized when the computer executes the readout program codes. Also, the functions of the above-described embodiment are realized when an OS (Operating System) running on the computer performs part or all of actual processing on the basis of the instructions of the program codes. 
   The functions of the above-described embodiment are also realized when the program codes read out from the storage medium are written in the memory of a function expansion card inserted into the computer or the memory of a function expansion unit connected to the computer, and the CPU of the function expansion card or function expansion unit performs part or all of actual processing on the basis of the instructions of the program codes. 
   As has been described above, according to the embodiment, a PD printer apparatus can be connected to a digital camera to receive image data from the digital camera and print the image data. 
   The digital camera according to the embodiment can determine in accordance with the function of the connected printer apparatus whether to output, to the printer apparatus, a JPEG code or decoded data as a data file structure. Data of the determined structure is transmitted to the connected printer apparatus and printed. 
   The printer apparatus and digital camera according to the embodiment request the start of print operation using a command in which all the parameters of a print request command from the digital camera are set to “0”. This can simplify communication procedures between the printer apparatus and the digital camera. 
   In the number-of-prints count display, the number of printed sheets can be accurately counted and displayed even in a mode in which a plurality of images are printed on one sheet. 
   The embodiment has exemplified a digital camera as an imaging apparatus, but the present invention is not limited to this. For example, cell phones with an imaging function and a function of saving sensed image data have recently been known. Instead of the digital camera described in the embodiment, such a cell phone can be connected via a connection cable. 
   As a portable information terminal, PDAs (Personal Digital Assistances) having a liquid crystal monitor capable of displaying an image and a memory capable of saving a sensed image have recently been spread. Such a PDA can be connected via a connection cable to print saved image data, similar to the digital camera in the embodiment. 
   The PD printer apparatus according to the embodiment can implement the functions of a PC printer, camera printer, and memory printer by one printer apparatus. 
   Other interfaces, e.g., wireless or using infrared ray such as Bluetooth, IRDA and the like may be provided. In this case, the digital camera determines a type of the printer when a communication between the digital camera and the printer has been established instead of when the camera and the printer are connected. 
   The present invention is not limited to the above embodiments and various changes and modifications can be made within the spirit and scope of the present invention. Therefore, to apprise the public of the scope of the present invention, the following claims are made.