JP3797373B2 - Image transfer using drawing command hook - Google Patents

Description

  The present invention relates to an image display system including an image supply device and an image display device connected via a network.

  As a kind of projector for projecting and displaying an image, a projector capable of projecting and displaying an image supplied from a personal computer via a network (hereinafter also referred to as “network projector”) has been proposed (for example, Patent Document 1). . In addition, a technique called VNC (Virtual Network Computing) is used to supply such a network projector with an image from a personal computer via a network.

International Publication No. 01/093583 Pamphlet

  However, when using VNC, an image is temporarily transferred from a VRAM (frame memory) in the computer to a RAM (system memory), and then the image is acquired from the RAM and transferred to the projector via the network. . Since transfer of image data from the VRAM to the RAM takes a considerable time, there is a case where a sufficient transfer speed cannot be obtained as a whole. Such a problem is not limited to a network projector system, and is generally a problem common to systems that supply and display images from an image supply apparatus to an image display apparatus via a network.

  An object of the present invention is to provide a technique for improving the transfer speed when transferring an image to an image display device via a network.

In order to achieve at least a part of the above object, an image supply device according to the present invention includes:
An image supply device for supplying and displaying an image on an image display device via a network,
An application program capable of issuing image drawing commands;
A drawing module for drawing an image in a frame memory for displaying an image on a display unit of the image supply device according to a drawing command issued by the application program;
A specific drawing command issued by the application program is hooked and acquired instead of the drawing module, and an image is drawn in a specific transfer image storage area in a general-purpose memory according to the acquired drawing command. A hook processing module for supplying a drawing command to the drawing module;
An image transfer processing module for transferring an image to the image display device via the network;
With
The drawing module has a function of drawing an image in a frame memory in accordance with a drawing command received from the application program or the hook processing module;
The image transfer processing module
A normal transfer mode for acquiring and transferring an image drawn in the transfer image storage area by the hook processing module when the image is drawn;
And a retransmission mode for acquiring and transferring an image drawn in the frame memory by the drawing module after drawing of the image is stopped.

  According to this image supply device, when a specific drawing command is issued, the hook processing module hooks and acquires the drawing command instead of the drawing module, and draws the image in the general-purpose memory. As described above, the entire transfer processing speed can be improved as compared with the case where the entire image to be transferred is transferred from VRAM to RAM (general purpose memory). Also, after the drawing of the image is stopped, it has a retransmission mode in which the image drawn in the frame memory by the drawing module is acquired and transferred, so that an image with a slightly deteriorated image quality was transferred in the normal transfer mode. Even in this case, a high-quality image can be transferred after drawing is stopped.

The hook processing module stores, in the general-purpose memory, first change area information indicating a first change area that is an area in which an image is drawn in accordance with the specific drawing command in the transfer image storage area. With a function to write in,
The image transfer processing module
In the normal transfer mode, the first change area that has been transferred is set as a retransmission area, and retransmission area information representing the retransmission area is written in the general-purpose memory,
In the retransmission mode, an image portion corresponding to at least a part of the retransmission area may be acquired from the frame memory and transferred.

  According to this configuration, between the image drawn in the transfer image storage area by the hook processing module according to a specific drawing command and the image drawn in the frame memory by the drawing module according to the same drawing command. Even when there is a difference between the images, it is possible to correctly transfer the image in the frame memory after the drawing is stopped.

Further, the image part corresponding to at least a part of the retransmission area is an image part corresponding to an area of a predetermined size in the retransmission area,
The image transfer processing module may transfer an image portion corresponding to an area of a predetermined size in the retransmission area in the retransmission mode, and delete the area of the predetermined size from the retransmission area.

  According to this configuration, since an image is retransmitted for each region of a predetermined size, the time required for one retransmission process can be shortened. In addition, when drawing is started in the middle of the transfer process in the retransmission mode several times, the normal transfer mode can be quickly returned, so that the process in the normal transfer mode is not excessively delayed.

The drawing module further has a function of writing second change area information indicating a second change area, which is an area in which an image is drawn in the frame memory, into the general-purpose memory;
In the normal transfer mode, the image transfer processing module is
(I) Referring to the first and second change area information stored in the general-purpose memory, the second change area corresponds to an area not included in the first change area. Obtaining an image portion from the frame memory;
(Ii) obtaining an image portion corresponding to the first change area from the transfer image storage area without obtaining from the frame memory;
(Iii) The acquired image portion may be transferred to the image display device via the network together with screen update area information indicating a screen update area that is a sum of the first and second change areas.

  Of the second change area, the area that is not included in the first change area is an area that is not drawn by the hook processing module. Since the image in this area is acquired from the frame memory, the image is transferred without omission. Is possible.

  The re-transmission mode may include a full-screen re-transmission mode in which an image of the full-screen area in the frame memory is acquired and transferred after a lapse of a predetermined period after drawing of the image is stopped.

  According to this configuration, the image of the entire screen area in the frame memory can be reliably transferred after the drawing of the image is stopped.

  In the full-screen retransmission mode, the image transfer processing module divides the full-screen area into a plurality of divided areas having a predetermined size, and is sequentially selected from the plurality of divided areas for each transfer process. You may make it complete the transfer of the image of the said full screen area | region by transferring the image of one division area.

  According to this configuration, since the image is retransmitted for each divided area of a predetermined size, the time required for one transfer process can be shortened. In addition, when drawing is started in the middle of the transfer process performed several times in the full-screen retransmission mode, the normal transfer mode can be quickly returned to, so that the process in the normal transfer mode is not excessively delayed.

The image transfer processing module further includes:
An image transferred in the normal transfer mode is selected from a plurality of compression methods including a first compression method with relatively large image degradation and a second compression method with relatively small image degradation. A function of compressing by a different compression method,
A function of registering an area of an image compressed and transferred by the first compression method in the normal transfer mode as a retransmission area that is an area of an image transferred in the retransmission mode;
The retransmission mode may have a function of compressing and transferring an image in the retransmission area by the second compression method.

  According to this configuration, an image that has been compressed and transferred with a compression method with large image degradation in the normal transfer mode is compressed and transferred with a compression method with small image degradation in the retransmission mode. Can be transferred.

The image transfer processing module is
The hook processing module may be loaded into the application program when the image transfer processing module is activated, and the hook processing module may be unloaded from the application program when the execution of the image transfer processing module is completed.

  According to this configuration, since the hook processing module works only when the image transfer process is performed, it is possible to prevent the hook processing module from desirably executing the hook process when the hook process is unnecessary.

  The present invention can be realized in various forms, for example, an image display system, an image supply device and an image display device that constitute the image display system, a hook processing module and an image transfer used in the image supply device. The present invention can be realized in various modes such as a processing module, an image supply method, a computer program for realizing the method or apparatus, and a recording medium on which the computer program is recorded.

Hereinafter, embodiments of the present invention will be described in the following order.
A. First embodiment:
B. Second embodiment:
C. Third embodiment:
D. Variations:

A. First embodiment:
FIG. 1 is an explanatory diagram showing the configuration of an image display system as an embodiment of the present invention. The image display system 10 of the present embodiment includes a personal computer 100 as an image supply device, a projector 200 as an image display device, and a network 300 that connects the computer 100 and the projector 200. The computer 100 has a function of supplying an image to the projector 200 via the network 300 and causing the projector 200 to project the image and display it on the projection display screen 70.

  FIG. 2 is a block diagram showing the internal configuration of the computer 100 and the projector 200. The computer 100 includes a CPU 102, a ROM 104, a RAM 106 as a general-purpose memory (also referred to as “system memory”), a hard disk drive 108, an input unit 110 including a keyboard and a pointing device, a network interface unit 112, A VRAM 114 as a frame memory, a graphic controller 116, a display device 118 such as a liquid crystal display, and a bus 120 for connecting these elements are provided.

  The RAM 106 stores various computer programs including an application program 122, a graphical device interface (GDI) 124, a display driver 126, a projector driver 128, and a VNC server 130 as an image transfer processing module. Has been. The GDI 124, the display driver 126, and the projector driver 128 function as a part of the operating system. In this embodiment, Windows (registered trademark) provided by Microsoft Corporation is assumed as the operating system. Such various computer programs are provided in a form recorded on a computer-readable recording medium such as a flexible disk or a CD-ROM.

  The projector 200 includes a CPU 202, a ROM 204, a RAM 206, an input unit 210 including various operation buttons, a network interface unit 212, an image processing unit 214, a light source lamp, a liquid crystal panel, and a projection unit 216 including a projection optical system. And a bus 218 for connecting these elements. The ROM 204 stores various computer programs including the image processing driver 228 and the VNC client 230.

  Hereinafter, before describing the function of the computer 100 in the embodiment, the function of a conventional computer using a VNC server will be described as a comparative example.

  FIG. 3 is an explanatory diagram showing a hierarchical structure of computer software and hardware in a comparative example. The application program 122 and the VNC server 130 belong to an application program layer (also referred to as “user application program layer”). The GDI 124, the display driver 126, and the projector driver 128 belong to the kernel layer. Further, the RAM 106 as a general-purpose memory, the network interface unit 112, the VRAM 114, the graphic controller 116, and the display device 118 belong to the hardware layer.

  In the embodiment, a case where a presentation program (for example, Microsoft PowerPoint) is used as the application program 122 will be described.

  The application program 122 issues various drawing requests to the GDI 124. The GDI 124 is a computer program that uniformly manages drawing on a display device (the display device 118 or the projector 200 of the computer 100) or a printing device (not shown). As is well known, the GDI 124 provides an application program interface (API: Application Program Interface) relating to drawing called “GDI function” to various application programs. Note that an API generally refers to a collection of procedures for an application program to use various functions of an operating system.

  For example, the application program 122 issues a drawing request for a presentation sheet image included in the presentation file to the GDI 124. Usually, the drawing request also includes information regarding the output destination of the image (that is, information specifying whether to output the image to the display device or the printing device).

  Note that other general-purpose drawing APIs may be used instead of the GDI 124. The “general-purpose drawing API” means an API that is commonly used for many application programs.

  The GDI 124, the display driver 126, and the projector driver 128 all function as a drawing module that executes a drawing process in accordance with a drawing command. Specifically, the GDI 124 receives the drawing request issued from the application program 122, checks the output destination of the image based on the drawing request, and if the output destination is a display device, the display driver 126 and the projector driver A drawing request is passed to each of 128.

  The display driver 126 draws image data in the VRAM 114 in accordance with the received drawing request. As is well known, the drawing request is not limited to drawing the entire screen, but frequently drawing a part of the screen. When receiving a drawing command for drawing a part of the screen, the display driver 126 draws only an image portion of an area to be drawn (also referred to as “change area”) in the VRAM 114. The graphic controller 116 displays an image on the display device 118 based on image data (that is, bitmap data) drawn in the VRAM 114. On the other hand, the projector driver 128 writes the change area information 106 a indicating the position and size of the drawing target area (that is, the change area) in the VRAM 114 in the RAM 106 in accordance with the drawing request received from the GDI 124.

  4A and 4B are explanatory diagrams showing examples of the change area information 106a and the image data storage area 106b in the RAM 106. FIG. Here, it is assumed that the image to be projected and displayed by the projector changes from FIG. 4 (A) to FIG. 4 (B). As will be described later, the image data storage area 106 b stores image data transferred from the VRAM 114 by the VNC server 130. The image data storage area 106b preferably has the same data capacity as the VRAM 114 (frame memory).

  The change area Ra is an area of an image portion drawn by a drawing command when changing the image from FIG. 4 (A) to FIG. 4 (B). The change area information 106a regarding the change area Ra includes the x coordinate Xa and the y coordinate Ya of the reference point (usually the upper left point) of the change area Ra, and the width Wa and the height Ha of the change area Ra. The coordinates (Xa, Ya) of the reference point are data indicating the position of the change area Ra, and the width Wa and the height Ha are data indicating the size of the change area Ra.

  The VNC server 130 refers to the change area information 106 a in the RAM 106 and transfers the image data in the change area Ra from the VRAM 114 to the image data storage area 106 b in the RAM 106. The image data storage area 106b is a memory area having a size equal to the display resolution of the computer 100 or the projector 200, for example. The VNC server 130 further reads out the image data of the change area Ra from the image data storage area 106b, and creates a screen update message including the change area information 106a of the change area Ra and the image data.

  FIG. 5 is an explanatory diagram showing the structure of the screen update message. This screen update message conforms to the structure of the frame buffer update “FramebufferUpdate” defined in the VNC protocol. The screen update message has a message header portion indicating a message type and a parameter portion indicating a message parameter.

  The message header part includes a message type (1 byte) indicating the type of message and a change area number (2 bytes) indicating the number of change areas. The data value of the message type indicating the screen update message is “0”. The data value of the number of change areas is normally set to “1”. However, when the change area information 106a regarding a plurality of change areas remains unprocessed in the RAM 106, the screen update message includes information about the change areas (change area information and image data). It is also possible to construct an update message. The change area information included in the screen update message is also referred to as “screen update area information”. The message type data and the change area number data are divided through 1-byte padding.

  In the parameter section, the x coordinate (2 bytes) and y coordinate (2 bytes) of the reference point of the change area, the width (2 bytes) and height (2 bytes) of the change area, and the transfer of the image data of the change area Time encoding format (4 bytes) and change area image data (n bytes) are included. A predetermined format such as a JPEG format (data value “7”) is used as the encoding format.

  The VNC server 130 transfers the screen update message thus created to the projector 200 via the network interface unit 112.

  As described above, in the comparative example shown in FIG. 3, the image data once stored in the VRAM 114 is transferred to the RAM 106 which is a general-purpose memory, and then the image data in the RAM 106 is transferred to the projector 200. For this reason, it takes a considerable time to transfer data from the VRAM 114 to the RAM 106, and a sufficient transfer speed may not be obtained.

  FIG. 6 is an explanatory diagram showing a hierarchical structure of computer software and hardware in the first embodiment. 3 is different from the comparative example shown in FIG. 3 in that a hook processing module 400 is added between the application program 122 and the GDI 124, and two types of change area information 106a1 and 106a2 (hereinafter, “ Change area information A1, A2 "), and retransmission area information 106s (hereinafter referred to as" retransmission area information RS ") is stored in the RAM 106. It is the same as FIG. The hook processing module 400 hooks a specific drawing command issued by the application program 122 in advance and executes processing described later. Other drawing commands are processed by the GDI 124 as usual. Note that the hook processing module 400 is preferably configured exclusively for each application program so as to hook only a specific drawing command appropriate for the application program 122.

  The hook processing module 400 can also be considered as a kind of drawing API, but is distinguished from a general-purpose drawing API such as the GDI 124. That is, the hook processing module 400 is typically configured to process only specific drawing commands, whereas the GDI 124 is configured to process all drawing commands. .

  The hook processing module 400 is loaded (installed) into the application program 122 as a DLL (dynamic link library), for example. In general, an application program operates in units of “processes”. During execution of an application program, multiple modules (GDI32.DLL, Kernel32.DLL, etc.) are loaded in the process, and the application program performs various operations by using the functions in those modules. Is going. The “loading” of the hook processing module 400 means that the module 400 in which the hook procedure is mounted is incorporated in the process of the application program 122.

  When the hook processing module 400 is loaded, the function address of a specific drawing command issued from the application program 122 is the address of another function for executing a unique function implemented in the hook processing module 400. Is replaced. In the function of this unique function, processing for writing change information and image data into the RAM (described later) is executed, and then a normal GDI function is executed. When the hook processing module 400 is unloaded, the hook processing module 400 loaded in the process is unloaded after the function address replaced at the time of loading is restored.

  The hook processing module 400 can be loaded into the application program 122 and unloaded at any time as necessary. However, when the VNC server 130 is activated, the hook processing module 400 is loaded into a specific application program 122 (presentation program in this embodiment) that is operating, and when the VNC server 130 is terminated, the hook processing module 400 is loaded. Preferably, the VNC server 130 is configured to unload. In this way, since the hook processing module 400 can be operated only during the period when the VNC server 130 is being executed, a drawing command is hooked when the VNC server 130 is not executed (not activated) on the computer 100. And undesirable results can be avoided. In the present specification, the phrase “VNC server 130 is running on computer 100” means that the process of VNC server 130 is activated.

  FIG. 7 is an explanatory diagram showing an example of two change area information A1, A2 and retransmission area information RS. FIGS. 7A-1 to 7A-3 show states at time t100, and FIGS. 7B-1 to 7B-3 show states at time t101. It is assumed that the VNC server 130 repeatedly executes the transfer process at predetermined time intervals, and after the transfer is executed at time t100, the next transfer is executed at time t101.

  The first change area information A1 shown in FIG. 7A-1 is an area RA1 (referred to as “change area RA1”) drawn directly in the image data storage area 106b in the RAM 106 by the hook processing module 400 (FIG. 6). ). The image in the change area RA1 is referred to as “image G1”. The first change area information A1 is written into the RAM 106 by the hook processing module 400. Second change area information A2 shown in FIG. 7A-2 represents an area RA2 (referred to as “change area RA2”) drawn in the VRAM 114 by the display driver 126 (FIG. 6). The image in the change area RA2 is referred to as “image G2.” The second change area information A2 is written in the RAM 106 by the projector driver 128. The retransmission area information RS shown in FIG. 7A-3 is drawn in the image data storage area 106b directly by the hook processing module 400 and then transferred to the past first change area RA1 ("Retransmission area") by the VNC server 130. RRS)). In the transfer process before time t100, it is assumed that the first change area RA1 does not exist, and therefore, retransmission area information RS is not registered at time t100. The retransmission area information RS is written into the RAM 106 by the VNC server 130.

  In the example of FIG. 7, a state in which the areas RA1, RA2, and RRS are arranged in the same screen area SCA is shown. Here, the “screen area SCA” means the entire area of the image stored in the VRAM 114, which is equal to the entire area of the image data storage area 106b. Strictly speaking, the first change area RA1 is an area defined by an address in the image data storage area 106b, and the second change area RA2 and the retransmission area RRS are areas defined by an address in the VRAM 114. However, these can be expressed by the same screen area SCA.

  As shown in FIGS. 7B-1 to (B-3), at time t101, the first and second change region information A1 and A2 do not exist, and the retransmission region information RS is the region of the image G1 (that is, , The same region as the first change region RA1 at time t100). In FIG. 7 (B-3), for convenience of illustration, retransmission area RRS is drawn with a one-dot chain line.

  As will be described below, the VNC server 130 executes normal transfer processing (also referred to as “normal transfer mode”) based on the change area information A1 and A2 at time t100. At time t101, since there is no change area information A1, A2, retransmission processing (also referred to as “retransmission mode”) is executed based on retransmission area information RS.

  Even if retransmission area information RS is registered at time t100, normal transfer processing is executed at time t100, not retransmission processing. That is, when either one of the two change area information A1 and A2 exists, the normal transfer process is executed, and both of the two change area information A1 and A2 do not exist and the retransmission area information RS exists. In this case, retransmission processing is executed.

  FIG. 8 is a flowchart showing the operations of the hook processing module 400 and the VNC server 130 in the first embodiment. Steps S10 to S16 are executed by the hook processing module 400, and steps S20 to S26 are periodically executed by the VNC server 130.

  When a specific drawing command is issued from the application program 122, the hook processing module 400 hooks the drawing command in step S10 and acquires the drawing command instead of the GDI 124. Note that it is preferable that the drawing command hooked by the hook processing module 400 is not limited to all drawing commands, but only limited specific drawing commands. This is because there are many drawing commands issued by the application program 122. If all of them are hooked, there is a possibility that the processing speed may be lowered or the desired drawing may not be performed. Because.

  In step S12, a process of registering the change area information is executed according to the acquired drawing command. Specifically, the hook processing module 400 acquires the position and size of the area (the change area RA1 in FIG. 7A-1) where drawing is performed according to the drawing command, and changes area information A1 representing the change area is obtained. A process of directly writing to the RAM 106 is executed.

  In step S14, the image data writing process of the change area RA1 is executed. Specifically, the hook processing module 400 executes a process of expanding the image data in the change area RA1 in accordance with the drawing command and directly writing the image data in the image data storage area 106b in the RAM 106.

  In step S16, the hook processing module 400 calls a normal GDI function according to the drawing command acquired in step S10, and executes the drawing process. Note that the display driver 126 and the projector driver 128 (FIG. 6) execute respective processes in accordance with the drawing command received from the GDI 124, as in the comparative example shown in FIG. That is, the display driver 126 draws an image in the VRAM 114, and the projector driver 128 writes the change area information A2 indicating the drawing area in the RAM.

  On the other hand, in step S20, the VNC server 130 determines an area of image data to be transferred to the projector 200 (referred to as a “screen update area”). FIG. 9 is a flowchart showing the detailed procedure of step S20. In step S300, the retransmission flag is set to off. This retransmission flag is a flag indicating whether or not to perform retransmission processing. The ON state of the retransmission flag indicates that the retransmission process is executed, and the OFF state indicates that the normal transfer process is executed. Note that the retransmission flag is registered in the RAM 106.

  In steps S302 and S304, first and second change area information A1 and A2 are acquired. As described above, the first change area information A1 is information representing an area drawn in the image data storage area 106b in the RAM 106 by the hook processing module 400, and is written in the RAM 106 by the hook processing module 400. It is. On the other hand, the second change area information A2 is information representing an area drawn in the VRAM 114 by the display driver 126, and is written in the RAM 106 by the projector driver 128.

  FIG. 10A shows two change areas RA1 and RA2 and a retransmission area RRS at time t100 (FIGS. 7A-1 to 7A-3). However, there is no retransmission area RRS at time t100.

  In the example of FIG. 10A, the two change areas RA1 and RA2 partially overlap, but the two change areas RA1 and RA2 may have various other relationships. For example, there are cases where the two change regions RA1 and RA2 do not overlap at all, and there are also cases where the two change regions RA1 and RA2 completely overlap. For example, when the hook processing module 400 performs drawing in accordance with a specific drawing command, and then the normal drawing modules 124, 126, and 128 perform drawing in the same region in accordance with the same drawing command, the two change regions RA1, RA2 Are the same. However, even when the same drawing command is executed, there may be a slight difference between the two change areas RA1 and RA2 depending on the setting of each module.

  FIG. 10B shows an area TG1 where the VNC server 130 directly acquires an image from the RAM 106 at the time t100 during image transfer, and FIG. 10C shows an area TG2 where the image is acquired from the VRAM 114. These areas TG1 and TG2 are also referred to as “transfer areas”. As can be understood from this example, in the normal transfer process, the image of the first change area RA1 (= TG1) is directly acquired from the RAM 106, and the first change area RA1 among the second change areas RA2 is obtained. The image of the area TG2 that is not included in the area is acquired from the VRAM 114. The reason for this distinction is to reduce the number of images acquired from the VRAM 114 as much as possible and reduce the time required for the acquisition. For example, when the two change areas RA1 and RA2 are completely overlapped, it is not necessary to acquire an image from the VRAM 114, so that the transfer process can be performed at high speed. FIG. 10D shows the entire area (screen update area TTG) transferred by the VNC server 130 at time t100. This screen update area TTG corresponds to the sum area of the first and second change areas RA1 and RA2.

  The first change area information A1 may include a plurality of information corresponding to a plurality of drawing commands. In this case, the sum area of the drawing areas of the plurality of drawing commands becomes the first change area RA1. The same applies to the second change area RA2 and the retransmission area RRS.

  In step S306 in FIG. 9, it is determined whether or not both of the two change areas RA1 and RA2 are empty. When the two change areas RA1 and RA2 are both empty, retransmission processing is executed in step S314 described later. On the other hand, when one of the two change areas RA1 and RA2 is not empty, normal transfer processing is executed in steps S308 to S312.

  In step S308 in FIG. 9, the difference between the change areas RA1 and RA2 represented by the two types of change area information A1 and A2 is calculated. Specifically, a region TG2 (FIG. 10C) that is not included in the first change region RA1 in the second change region RA2 is calculated.

  In step S310, the first change area information A1 is added as retransmission area information RS. As a result, the first change area information A1 at time t100 can be used as retransmission area information RS after the next time t101.

  In step S312, the optimization process of the screen update area TTG (FIG. 10D) is executed. FIG. 11 is an explanatory diagram showing the contents of the optimization process of the screen update area. FIG. 11A shows the same screen update area TTG as in FIG. In the optimization process, as shown in FIG. 11B, the screen update area TTG is divided into adjacent rectangular areas R11 to R13 that do not overlap each other. And these rectangular area | regions R11-R13 are employ | adopted as a screen update area | region after optimization. Since each of the screen update areas R11 to R13 is rectangular, it is possible to reduce the amount of image data to be transferred compared to the case of transferring a rectangular image including the screen update area TTG before optimization. is there.

  In step S22 of FIG. 8, image data of an image portion corresponding to the screen update area is acquired. FIG. 12 is a flowchart showing the detailed procedure of step S22. In step S70, it is checked whether or not the second transfer area TG2 (FIG. 10C) is empty. The “second transfer area TG2” is an area in which image data is acquired from the VRAM 114 in the screen update area TTG as described above. When the second change area information A2 does not exist and when the second change area A2 is completely included in the first change area A1, the second transfer area TG2 is empty. If the second transfer area TG2 is empty, the process proceeds to step S74 described later. On the other hand, if the second transfer area TG2 is not empty, step S72 is executed. In step S72, the VNC server 130 acquires the image data in the second transfer area TG2 from the VRAM 114 and writes it in the image data storage area 106b in the RAM 106. As a result, all the images in the screen update area TTG shown in FIG. 10D are stored in the image data storage area 106b. In step S74, the VNC server 130 acquires the image data of the screen update area TTG from the image data storage area 106b of the RAM 106. Note that what is actually acquired is the image data of the individual screen update areas R11 to R13 (FIG. 11B) after the optimization processing.

  In step S24 of FIG. 8, the image data is converted according to any of a plurality of preset encoding formats (also referred to as “compression method” or “compression method”). FIG. 13 is a flowchart showing the detailed procedure of step S24. In step S502, it is determined whether or not the retransmission flag is off. When the retransmission flag is off (in the case of normal transfer processing), the image is compressed by JPEG compression. On the other hand, when the retransmission flag is on (in the case of retransmission processing), the image is compressed by ZLIB compression. As is well known, ZLIB compression is a compression method (lossless compression) that is lossless and has no image quality degradation. In this embodiment, JPEG compression is used in the normal transfer process, so that the amount of image data can be reduced and the transfer speed can be increased. On the other hand, since the ZLIB compression is used in the retransmission process, it is possible to transfer a higher quality image.

  It should be noted that various compression methods other than these can be employed as the compression method. The same compression method may be used for the normal transfer process and the retransmission process. When using different compression methods for normal transfer processing and retransmission processing, select a compression method from multiple compression methods, including compression methods with relatively large image quality degradation and compression methods with relatively small image quality degradation. Preferably it can be done. In this case, it is preferable to use a compression method with relatively large image quality degradation in the normal transfer processing, and a compression method with relatively little image quality degradation in the retransmission processing. The reason for this is that the retransmission process is executed when drawing is stopped, and the quality of the image quality is conspicuous, so that a higher quality image is desired to be transferred.

  In step S <b> 26 of FIG. 8, a screen update message (FIG. 5) including the image data thus converted and the change area information is created and transferred to the projector 200 via the network interface unit 112.

  When the network interface unit 212 (FIG. 2) of the projector 200 receives the communication data supplied via the network 300, the network interface unit 212 (FIG. 2) extracts a screen update message included in the communication data and passes it to the VNC client 230. The VNC client 230 passes the image data included in the screen update message to the image processing driver 228. The image processing driver 228 controls the image processing unit 214 according to the image data, and causes the image processing unit 214 to develop the image data in a display memory (not shown) in the image processing unit 214. As a result, the projector 200 can display an image on the projection display screen 70 as shown in FIG.

  Also at time t101, the processing of steps S20 to S26 in FIG. 8 is executed in the same manner. However, at time t101, as shown in FIGS. 7B-1 to 7B-3, there is no change area information A1, A2, and information representing the area of the image G1 is registered as retransmission area information RS. ing. The absence of both of the two change area information A1 and A2 means that there has been no image drawing command (image drawing has been stopped). At this time, since the change areas RA1 and RA2 are both empty in step S306 in FIG. 9, the retransmission process in step S314 is executed.

  FIG. 14 is a flowchart showing a detailed procedure of step S314. In step S320, it is determined whether or not retransmission area RRS is empty. If the retransmission area RRS is empty, the process is terminated as it is. In this case, the retransmission process is not actually executed. On the other hand, if the retransmission area RRS is not empty, the processes of steps S322 to S326 are executed.

  FIG. 15 is an explanatory diagram showing the processing content of step S322. As shown in FIG. 15A, the first and second change areas RA1 and RA2 do not exist at time t101, and the retransmission area RRS is an area of the image G1. At this time, in step S322 of FIG. 14, as shown in FIGS. 15B and 15C, a region DP having a predetermined size at the head of the retransmission region RRS is divided (or extracted), and this region DP is Is added to the second transfer area TG2. Since the change areas RA1 and RA2 are empty, only the divided area DP is set as the second transfer area TG2. In step S322, the segment area DP is further deleted from the retransmission area RRS. FIG. 15D shows the re-transmission area RRS 'after this correction. At time t101, the first transfer area TG1 (an area in which an image is directly acquired from the RAM 106) is empty, so the second transfer area TG2 and the screen update area TTG (FIG. 15E) are equal. Therefore, all the images in the screen update area TTG are acquired from the VRAM 114 and transferred.

  Note that it is possible to set the entire retransmission area RRS instead of a part thereof as the second transfer area TG2. In other words, at least a part of the retransmission area RRS may be set as the second transfer area TG2. However, if only the area DP of a predetermined size in the retransmission area RRS is set as the second transfer area TG2 as in the present embodiment, the time required for one retransmission process can be shortened. it can. In addition, when drawing is started in the middle of several retransmission processes, it is possible to quickly return to the normal transfer process, and there is an advantage that the process by the normal transfer process is not excessively delayed.

  The size of the divided area DP is preferably a predetermined size set in advance. Here, the “predetermined size” is not limited to the case where both the height and width of the region DP are determined in advance, but only when the height is determined in advance and the width is arbitrary (retransmission region RRS). The data size of the area DP (how many bytes from the beginning), when only the width is predetermined and the height is arbitrary (when set equal to the height of the retransmission area RRS) It has a broad meaning encompassing various cases such as the case where ()) is set.

  In step S324 in FIG. 14, the optimization process of the screen update area TTG is executed. This process is the same as the optimization process (FIG. 11) in the normal transfer process. In step S326, the retransmission flag is set on.

  When the screen update area is thus determined, step S22 (FIG. 12), step S24 (FIG. 13), and step S26 of FIG. 8 are sequentially executed. Note that the processing content of steps S22 to S26 in the retransmission processing is different from the processing content of the normal transfer processing only in that ZLIB compression is executed in step S500 of FIG. Since the retransmission processing uses ZLIB compression, it is possible to transfer a higher quality image.

  As described above, in the first embodiment, the hook processing module 400 hooks a specific drawing command to prefetch and executes a process of directly writing the image data of the change area to the RAM 106. As a result, the time required to transfer the image data from the VRAM 114 to the RAM 106 in the comparative example shown in FIG. 3 can be saved. As a result, there is an advantage that the transfer speed when image data is transferred to the projector 200 can be sufficiently increased.

  In a general personal computer, data transfer from the RAM 106 to the VRAM 114 can be executed at a very high speed, whereas data transfer from the VRAM 114 to the RAM 106 can be executed only several times slower than that. There are many. In the first embodiment, since the data transfer from the low-speed VRAM to the RAM can be reduced, the time required to transfer the image data to the projector 200 can be greatly reduced.

  In the first embodiment, in the normal transfer process, the image portion of the area TG2 (FIG. 10C) not drawn by the hook processing module 400 is acquired from the VRAM 114 and transferred to the projector 200. As a result, the images drawn by the normal drawing modules 124, 126, and 128 can be transferred to the projector 200 without omission.

  Furthermore, in the first embodiment, the first change area RA1 is registered as the retransmission area RRS during the normal transfer process, and the image in the retransmission area RRS is acquired from the VRAM 114 and retransmitted when image drawing stops. The During the normal transfer process, the image of the first change area RA1 is directly acquired from the RAM 106, but even when the image quality of this image is not desirable, it is possible to retransmit the high-quality image after the drawing is stopped. . This is particularly effective in the following cases.

  That is, when a specific drawing command is issued from the application program 122, the drawing command is passed to the GDI 124 via the hook processing module 400. At this time, depending on the drawing command, the GDI 124 may further process the image data. In this case, a difference occurs between the image drawn by the hook processing module 400 in the image data storage area 106 b in the RAM 106 and the image drawn by the display driver 126 in the VRAM 114. The image in the first change area RA1 is directly acquired from the image data storage area 106b, transferred to the projector 200, and displayed. On the other hand, the image is drawn on the VRAM 114 by the display driver 126 on the screen of the computer 100 (FIG. 1). Displayed. Originally, it is desired to display the same image as the image displayed on the computer 100 on the projector 200, but this cannot be realized when the GDI 124 processes the image. However, since the difference between the two images is usually slight, there is a difference between the images displayed on the projector 200 and the computer 100 while the drawing is continuously executed and any changes are made to the image on the screen. However, it is not a big problem. On the other hand, when the drawing is stopped, the observer can observe the image in more detail, and thus the image displayed on the projector 200 may feel unsatisfactory. In the first embodiment, after drawing is stopped, the image in the retransmission area RRS is acquired from the VRAM 114 and transferred, so that the desired image can be displayed on the projector 200 even in such a case.

  In the above embodiment, the retransmission process is started immediately when drawing is stopped. However, the retransmission process may be disclosed after the elapse of a predetermined period after the drawing is stopped.

B. Second embodiment:
FIG. 16 is a flowchart showing a detailed procedure of step S20 (screen update area determination processing in FIG. 8) in the second embodiment. The second embodiment is different from the first embodiment only in the processing contents of step S20 (more specifically, the contents of the retransmission process), and the other configurations and operations are the same as those of the first embodiment. In FIG. 16, step S400 is added between step S306 and step S308 of FIG. 9, and the contents of step S314a of the retransmission process are different from step S314 of FIG.

  In step S400, the stop count value CT and the segment area number N are initialized to zero. These parameters CT and N are parameters used in the retransmission process (step S314a). Since the normal transfer process (steps S308 to S312) is the same as that of the first embodiment, the description thereof is omitted.

  FIG. 17 is a flowchart showing a detailed procedure of step S314a (retransmission processing) in the second embodiment. In FIG. 17, steps S410 to S416 are added to steps S320 to S326 of FIG.

  In step S410, it is determined whether or not the stop count value CT is greater than or equal to a predetermined maximum value CTmax. The stop count value CT is a parameter indicating how many times transfer processing by the VNC server 130 has been started since drawing has stopped. If the stop count value CT is less than the maximum value CTmax, the stop count value CT is incremented by 1 in step S412, and the retransmission processing in steps S320 to S326 is executed. Therefore, the retransmission process of steps S412 and S320 to S326 is repeatedly executed (CTmax-1) times after the drawing is stopped. Note that the processing in steps S320 to S326 is the same as the processing described in the first embodiment (FIG. 15), and thus description thereof is omitted.

  On the other hand, when the stop count value CT becomes equal to or greater than the maximum value CTmax, step S414. The process of S416 ("full screen retransmission process") is executed. That is, this full-screen retransmission process is executed when the stop count value CT becomes equal to or greater than the maximum value CTmax, regardless of whether or not the retransmission area information RS is registered. The maximum value CTmax is set to a value corresponding to about 1 second after drawing is stopped, for example.

  In step S414, the value of the segment area number N is incremented by one. This divided area number N is a parameter for indicating the number (ordinal number) of each divided area when the entire screen area is divided into a plurality of areas with a predetermined size. In step S416, the Nth segment area in the entire screen area is added to the second transfer area TG2, and the process proceeds to step S326, where the retransmission flag is set to ON.

  FIG. 18 is an explanatory diagram showing the contents of steps S414 and S416. In the full screen retransmission process, the entire screen area SCA is divided into a plurality of divided areas DDP1 to DDPn having a predetermined size. Then, at time t200 (FIG. 18A) when CTmax ≦ CT, the first segment area DDP1 is set as the second transfer area TG2. At the next time t201 (FIG. 18B), the second segment area DDP2 is set as the second transfer area TG2. As a result, the full-screen image is transferred to the projector 200 by a plurality of retransmission processes.

  Note that it is possible to set not the entire screen area SCA but the whole as the second transfer area TG2. However, as in the present embodiment, if only a part of the segment area of the screen area SCA is set as the second transfer area TG2, the time required for one retransmission process can be shortened. In addition, when drawing is started in the middle of a plurality of retransmission processes, it is possible to quickly return to the normal transfer process, and there is an advantage that the process by the normal transfer process is not excessively delayed.

The sizes of the divided areas DDP1 to DDPn are preferably a predetermined size set in advance. Here, the “predetermined size” is not limited to the case where both the height and width of the segmented area are determined in advance, but only when the height is determined in advance and the width is arbitrary (in the screen area SCA). If the width is predetermined and the height is arbitrary (set equal to the height of the screen area SCA), the data size of the section area (how many bytes from the top) Has a broad meaning including various cases such as

  The full-screen retransmission process is also referred to as “full-screen retransmission process” or “full-screen retransmission mode”. The full-screen retransmission process is different from the retransmission process described with reference to FIGS. 14 and 15 in the first embodiment in that the retransmission area information RS is not used. The retransmission process using the retransmission area information RS can also be referred to as a narrowly defined retransmission process. In the second embodiment, only the full-screen retransmission process may be executed without executing the narrowly-defined retransmission process.

  As described above, in the second embodiment, when the predetermined period elapses after the drawing is stopped, the process proceeds to the full screen retransmission process. Therefore, the image of the full screen area in the VRAM 114 can be transferred after the drawing of the image is stopped. Is possible. Therefore, even if there is a difference between the image transferred by the normal transfer process and the retransmission process in the narrow sense using the retransmission area information RS and the image in the VRAM 114 for some reason, the computer 100 and the projector 200 It is possible to completely match the displayed images.

C. Third embodiment:
FIG. 19 is a flowchart showing a detailed procedure of step S24 (image data conversion processing of FIG. 8) in the third embodiment. The third embodiment is different from the first embodiment or the second embodiment only in the processing contents of step S24 (more specifically, the contents of the retransmission process), and the other configurations and operations are the first embodiment or the second embodiment. Same as example. FIG. 19 is obtained by adding steps S520 and S522 between step S500 and step S502 of FIG.

  In step S520, it is determined whether JPEG compression should be applied to the image in the image update area. Whether or not JPEG compression should be applied can be determined by analyzing image data, for example. Specifically, pixel values of a predetermined number of pixels at each of predetermined positions (for example, the four corners and the center) of the image are sampled to count the number of colors, and when the number of colors is less than a predetermined threshold, ZLIB compression is adopted, In the above case, JPEG compression may be adopted. For an image with a small number of colors, the amount of data can be considerably reduced even by ZLIB compression, so that a high-quality image can be transferred without excessively reducing the transfer speed. On the other hand, for images with a large number of colors, high-speed image transfer can be realized by adopting JPEG compression. The determination of which compression method to use may be made for each individual image to be rendered, or individual screen update regions after optimization (regions R11 to RR13 in FIG. 11B). It may be done every time.

  In step S522, retransmission area information RS indicating an image update area to be JPEG compressed is additionally registered. In this way, even when an image with slightly deteriorated image quality due to JPEG compression is transferred, a high-quality image can be retransmitted by resending processing after drawing is stopped.

  In the third embodiment, two types of areas to be transferred in the normal transfer process are registered as retransmission areas. That is, in step S310 in FIG. 9, the first change area RA1 is registered as the retransmission area, and in step S522 in FIG. 19, the area of the image transferred after JPEG compression is registered as the retransmission area.

  FIG. 20 shows an example of the relationship between the change areas RA1, RA2 and the retransmission area RRS in the third embodiment. 20A is the same as the first and second change areas RA1 and RA2 shown in FIG. 10A, and the screen update areas R11 to R13 in FIG. 20B are shown in FIG. It is the same as shown in. Here, the screen update area R11 is equal to the first change area RA1, and is an area drawn by hook processing. Therefore, this area RA1 is registered as a retransmission area regardless of whether JPEG compression or ZLIB compression is used to compress the image. It is assumed that JPEG compression is used when transferring images in the screen update areas R12 and R13. At this time, the screen update areas R12 and R13 are additionally registered as retransmission areas. As a result, as shown in FIG. 20C, all of the screen update areas R11 to R13 are registered as the retransmission area RRS.

  In the third embodiment, the first change area RA1 may not be registered as the retransmission area, but only the area of the image transferred by JPEG compression may be registered as the retransmission area. As described in the first embodiment, various compression methods other than JPEG compression and ZLIB compression can be used as the compression method.

  Thus, in the third embodiment, when transferring a JPEG compressed image, the area is registered as a retransmission area, and after drawing of the image is stopped, the image in the retransmission area is acquired from the VRAM 114 and transferred. Therefore, a high-quality image can be displayed on the projector 200.

D. Variations:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

D1. Modification 1:
As the screen update message supplied from the computer 100 to the projector 200, various messages other than those used in the above embodiment can be used. For example, a screen update message that includes at least image data can be used. Specifically, for example, when transferring image data of the entire screen, there is no need to transfer change area information.

  The screen update message preferably includes at least information indicating the position and size of the change area (screen update area) and image data in the change area. This is because the amount of data to be transferred is reduced if only the data relating to the change area (change area information and its image data) is transferred.

D2. Modification 2:
In the above-described embodiment, the image portion of the second transfer area TG2 is acquired from the VRAM 114 and once written in the image data storage area 106b in the RAM 106, and then the image of the screen update area TTG is acquired from the RAM 106 to connect the network. However, the process of writing to the image data storage area 106b can be omitted. However, according to the procedure of the above-described embodiment, when an image is finally transferred through the network, the image can be acquired from one image data storage area 106b.

D3. Modification 3:
In the above embodiment, the drawing module is divided into three modules, the GDI 124, the display driver 126, and the projector driver 128. However, the modules can be arbitrarily classified, and these functions can be combined into one module. It is also possible to combine the functions of the display driver 126 and the projector driver 128 into one module.

D4. Modification 4:
In the above embodiment, a personal computer is used as the image supply device, but other types of computers (mobile computer, handheld computer, workstation, etc.) may be used instead. In addition to these computers, devices that can be connected to a network and have the same functions as the computer may be used. Such devices include, for example, information mobile terminals, mobile phones, mail terminals, game machines, set top boxes, and the like. As the image display device, various display devices other than the projector can be used.

D5. Modification 5:
As the network, in addition to a local area network (LAN), various networks such as a wide area network (WAN), the Internet, and an intranet can be applied. The network may be configured by wire or may be configured by radio.

D6. Modification 6:
In the above embodiment, a part of the functions realized by software may be realized by hardware, or a part of the functions realized by hardware may be realized by software.

It is explanatory drawing which shows the structure of an image display system as one Example of this invention. It is a block diagram which shows the internal structure of a computer and a projector. It is explanatory drawing which shows the hierarchical structure of the software and hardware of a computer in a comparative example. It is explanatory drawing which shows the example of the change area information and image data storage area in an Example. It is explanatory drawing which shows the structure of a screen update message. It is explanatory drawing which shows the hierarchical structure of the software and hardware of a computer in an Example. It is explanatory drawing which shows the example of two change area information A1, A2, and resending area information RS. It is a flowchart which shows operation | movement of the hook process module and VNC server in 1st Example. It is a flowchart which shows the detailed procedure of step S20. It is explanatory drawing which shows the relationship between the change area | region at the time t100, a resending area | region, and a screen update area | region. It is explanatory drawing which shows the content of the optimization process of a screen update area | region. It is a flowchart which shows the detailed procedure of step S22. It is a flowchart which shows the detailed procedure of step S24. It is a flowchart which shows the detailed procedure of step S314. It is explanatory drawing which shows the content of the resending process. It is a flowchart which shows the detailed procedure of step S20 (screen update area | region determination process) in 2nd Example. It is a flowchart which shows the detailed procedure of step S314a (retransmission process) in 2nd Example. It is explanatory drawing which shows the content of step S414, S416 (full-screen resending process). It is a flowchart which shows the detailed procedure of step S24 (image data conversion process) in 3rd Example. It is explanatory drawing which shows an example of the relationship between change area | region RA1, RA2 and resending area | region RRS in 3rd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Image display system 60 ... Display screen 70 ... Projection display screen 100 ... Computer 102 ... CPU
104 ... ROM
106 ... RAM
106a ... Change area information 106b ... Image data storage area 106s ... Retransmission area information 108 ... Hard disk drive 110 ... Input section 112 ... Network interface section 114 ... VRAM
116: Graphic controller 118 ... Display device 120 ... Bus 122 ... Application program 124 ... GDI (graphics device interface)
126 ... Display driver 128 ... Projector driver 130 ... VNC server 200 ... Projector 202 ... CPU
204 ... ROM
206 ... RAM
210: Input unit 212 ... Network interface unit 214 ... Image processing unit 216 ... Projection unit 218 ... Bus 228 ... Image processing driver 230 ... VNC client 300 ... Network 400 ... Hook processing module

Claims (12)

An image supply device for supplying and displaying an image on an image display device via a network,
An application program capable of issuing image drawing commands;
A drawing module for drawing an image in a frame memory for displaying an image on a display unit of the image supply device according to a drawing command issued by the application program;
A specific drawing command issued by the application program is hooked and acquired instead of the drawing module, and an image is drawn in a specific transfer image storage area in a general-purpose memory according to the acquired drawing command. A hook processing module for supplying a drawing command to the drawing module;
An image transfer processing module for transferring an image to the image display device via the network;
With
The drawing module has a function of drawing an image in a frame memory in accordance with a drawing command received from the application program or the hook processing module;
The image transfer processing module
A normal transfer mode for acquiring and transferring an image drawn in the transfer image storage area by the hook processing module when the image is drawn;
An image supply apparatus comprising: a retransmission mode for acquiring and transferring an image drawn in the frame memory by the drawing module after drawing of the image is stopped. The image supply device according to claim 1,
The hook processing module stores, in the general-purpose memory, first change area information indicating a first change area that is an area in which an image is drawn in response to the specific drawing command in the transfer image storage area. And has a writing function,
The image transfer processing module
In the normal transfer mode, the first change area that has been transferred is set as a retransmission area, and retransmission area information representing the retransmission area is written in the general-purpose memory,
In the retransmission mode, an image supply device that acquires and transfers an image portion corresponding to at least a part of the retransmission area from the frame memory. The image supply device according to claim 2,
An image portion corresponding to at least a part of the retransmission region is an image portion corresponding to a region of a predetermined size in the retransmission region;
The image supply processing module, wherein the image transfer processing module transfers an image portion corresponding to a predetermined size area of the retransmission area in the retransmission mode and deletes the predetermined size area from the retransmission area. The image supply device according to claim 2, wherein
The drawing module further has a function of writing second change area information indicating a second change area, which is an area in which an image is drawn in the frame memory, into the general-purpose memory;
In the normal transfer mode, the image transfer processing module is
(I) Referring to the first and second change area information stored in the general-purpose memory, the second change area corresponds to an area not included in the first change area. Obtaining an image portion from the frame memory;
(Ii) obtaining an image portion corresponding to the first change area from the transfer image storage area without obtaining from the frame memory;
(Iii) An image supply device that transfers the acquired image portion to the image display device via the network together with screen update region information indicating a screen update region that is a sum of the first and second change regions. The image supply device according to any one of claims 1 to 4,
The re-transmission mode includes a full-screen re-transmission mode in which an image of a full-screen area in the frame memory is transferred after a predetermined period has elapsed since drawing of the image is stopped. The image supply device according to claim 5,
In the full-screen retransmission mode, the image transfer processing module divides the full-screen area into a plurality of divided areas having a predetermined size, and is sequentially selected from the plurality of divided areas for each transfer process. An image supply device that completes the transfer of the image of the entire screen area by transferring an image of one divided area. The image supply device according to any one of claims 1 to 6,
The image transfer processing module further includes:
An image transferred in the normal transfer mode is selected from a plurality of compression methods including a first compression method with relatively large image degradation and a second compression method with relatively small image degradation. A function of compressing by a different compression method,
A function of registering an area of an image compressed and transferred by the first compression method in the normal transfer mode as a retransmission area that is an area of an image transferred in the retransmission mode;
A function of compressing and transferring an image in the retransmission area by the second compression method in the retransmission mode;
An image supply apparatus. The image supply device according to any one of claims 1 to 7,
An image supply configured to load the hook processing module into the application program when the image transfer processing module is activated and unload the hook processing module from the application program when the execution of the image transfer processing module is completed. apparatus. An image transfer processing module program used in an image supply device for supplying and displaying an image on an image display device via a network,
The image supply device includes an application program capable of issuing an image drawing command and a drawing for drawing an image in a frame memory for displaying an image on a display unit of the image supply device according to the drawing command issued by the application program A module and a specific drawing command issued by the application program are hooked and acquired instead of the drawing module, and an image is drawn in a specific transfer image storage area in the general-purpose memory according to the acquired drawing command. A hook processing module for supplying the acquired drawing command to the drawing module;
The image transfer processing module program is configured to cause a computer to realize a function of transferring an image to the image display device via the network.
The drawing module has a function of drawing an image in a frame memory in accordance with a drawing command received from the application program or the hook processing module;
The image transfer processing module program is
A normal transfer mode for acquiring and transferring an image drawn in the transfer image storage area by the hook processing module when the image is drawn;
An image transfer processing module configured to cause a computer to realize a retransmission mode for acquiring and transferring an image drawn in the frame memory by the drawing module after drawing of the image is stopped program. An image transfer processing device used in an image supply device for supplying and displaying an image on an image display device via a network,
The image supply device includes an application program capable of issuing an image drawing command and a drawing for drawing an image in a frame memory for displaying an image on a display unit of the image supply device according to the drawing command issued by the application program A module and a specific drawing command issued by the application program are hooked and acquired instead of the drawing module, and an image is drawn in a specific transfer image storage area in the general-purpose memory according to the acquired drawing command. A hook processing module for supplying the acquired drawing command to the drawing module;
The image transfer processing device has a function of transferring an image to the image display device via the network,
The drawing module has a function of drawing an image in a frame memory in accordance with a drawing command received from the application program or the hook processing module;
The image transfer processing device includes:
A normal transfer mode for acquiring and transferring an image drawn in the transfer image storage area by the hook processing module when the image is drawn;
An image transfer processing apparatus comprising: a retransmission mode for acquiring and transferring an image drawn in the frame memory by the drawing module after drawing of the image is stopped. A drawing module that draws an image in a frame memory for displaying an image on the display unit of the image supply device according to a drawing command issued by an application program, and the drawing by hooking a specific drawing command issued by the application program A hook processing module that obtains instead of the module, draws an image in a specific transfer image storage area in the general-purpose memory in accordance with the obtained drawing command, and supplies the obtained drawing command to the drawing module. A method for supplying and displaying an image from an image supply device to an image display device via a network,
(A) the hook processing module rendering an image in a specific transfer image storage area in the general-purpose memory in response to a specific rendering command issued by the application program;
(B) the image supply device acquires and transfers an image drawn in the transfer image storage area when drawing of an image is performed in accordance with a drawing command;
(C) the image supply device obtains an image drawn in the frame memory after image drawing stops and transfers the image via the network;
An image supply method comprising: A computer-readable recording medium recording an image transfer processing module used in an image supply device for supplying an image to an image display device via a network for display.
The image supply device includes an application program capable of issuing an image drawing command and a drawing for drawing an image in a frame memory for displaying an image on a display unit of the image supply device according to the drawing command issued by the application program A module and a specific drawing command issued by the application program are hooked and acquired instead of the drawing module, and an image is drawn in a specific transfer image storage area in the general-purpose memory according to the acquired drawing command. A hook processing module for supplying the acquired drawing command to the drawing module;
The image transfer processing module causes a computer to execute a process of transferring an image to the image display device via the network;
The drawing module has a function of drawing an image in a frame memory in accordance with a drawing command received from the application program or the hook processing module;
The image transfer processing module
A normal transfer mode for acquiring and transferring an image drawn in the transfer image storage area by the hook processing module when the image is drawn;
And a retransmission mode for acquiring and transferring an image drawn in the frame memory by the drawing module after drawing of the image is stopped.

Images