JP2006127280A - Memory management program and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a memory management program that can increase free space in a working memory by reducing the size of data in the working memory and reduce an increase in a processing load on a CPU when an application program uses data in the working memory. <P>SOLUTION: The memory management program, which manages a heap area of the working memory 140 of an image display device 14 for displaying image data on a display 12, reduces the information amount of image data in the heap area when the unreferenced interval that is an elapsed time from the last reference by an application program to the image data loaded from an external storage device 144 to the heap area of the working memory 140 reaches a predetermined reduction threshold. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image display technique for displaying image data.

  In a computer system, management of working memory is an extremely important factor that greatly affects the execution performance and reliability of application programs. The C language can perform detailed control of hardware and can improve the execution performance of an application program. However, there are various control items, and it may be difficult to optimally control the hardware. For example, in the C language, after the working memory area is used, it is necessary to explicitly release the used working memory area. When many application programs that do not perform the releasing process are executed, In some cases, the operation of the system becomes unstable due to a decrease in free space in the working memory, a so-called memory shortage. Also, in embedded devices where the processing speed of the CPU and the capacity of the working memory are small compared to a PC (Personal Computer), etc., use at least limited hardware resources before increasing the performance of application programs. Management of working memory is particularly important because it is required to continue to operate reliably.

  In order to suppress memory shortage caused by forgetting to free up used area of working memory, work with compressed data when loading data stored in compressed form in external storage device to working memory A technique for reducing the amount of data loaded into a working memory by loading data into a memory and expanding data loaded by an application program at the stage of actual use is known (see, for example, Patent Document 1).

JP 2002-169695 A

  However, in the technique described in Patent Document 1, it is necessary to develop data when it is actually used by an application program, and the processing load on the CPU may increase at the timing of processing the data. In the technique described in Patent Document 1, an area for expanding compressed data is required in the working memory, and the required area depends on the data to be expanded. It was necessary to secure a sufficiently large area to cope with it, and the use efficiency of the working memory might be reduced.

  SUMMARY An advantage of some aspects of the invention is that it provides a memory management program and an image display apparatus that can solve the above-described problems. For example, the size of the data on the working memory is reduced, and when the application program uses the data on the working memory, an increase in the processing load on the CPU is kept low.

  In order to solve the above problem, the memory management program of the present invention has a non-reference period, which is an elapsed time since the image data loaded in the heap area is last referred, equal to or less than a predetermined reduction threshold. In this case, the information amount of the image data in the heap area is reduced.

  For example, a memory management program for managing a heap area of a working memory included in an image display device that displays image data on a display, and image data loaded from an external storage device to a heap area of the working memory is stored in the image display device When the non-reference period measuring means for measuring the non-reference period, which is the elapsed time since the last reference by the application program, and the non-reference period measured by the non-reference period measuring means are greater than or equal to a predetermined reduction threshold The present invention provides a memory management program characterized by realizing an information amount reducing means for reducing the information amount of image data in a heap area.

  According to the present invention, the amount of information of image data with a low reference frequency can be reduced on the memory, so that it is possible to suppress a decrease in the free area of the working memory.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 shows an example of a hardware configuration of an image display system 10 according to an embodiment of the present invention. The image display system 10 includes a display 12 and an image display device 14. The display 12 is a monitor such as an LCD (Liquid Crystal Display) or a CRT (Cathode Ray Tube), and displays image data output by the image display device 14.

  The image display device 14 includes a work memory 140, a video memory 142, an external storage device 144 such as an HDD (Hard Disk Drive), a CPU 146, and a bus 148. The external storage device 144 stores an OS (Operating System) that operates the image display device 14, application programs, setting data and image data handled by the OS and application programs, and the like. The external storage device 144 may be a ROM or a removable storage medium in addition to the HDD.

  The working memory 140 holds an application program being executed among the application programs stored in the external storage device 144. The work memory 140 also holds setting data, image data, and the like used by the application program being executed. The video memory 142 holds image data that needs to be displayed among the image data held in the work memory 140 in accordance with the operation of the OS or application program being executed. The video memory 142 is connected to the display 12, and the image data written in the video memory 142 is displayed on the display 12.

  The CPU 146 loads setting data and image data used in the application program together with the application program stored in the external storage device 144 to the heap area of the work memory 140, and executes the application program. Then, the CPU 146 reads out the image data that needs to be displayed in accordance with the operation of the application program from the heap area of the work memory 140 and copies it to the video memory 142, thereby displaying the image data on the display 12. Let The bus 148 connects the working memory 140, the video memory 142, the external storage device 144, and the CPU 146 to each other.

  In this example, the image data is stored in the external storage device 144 in a compressed state, and the CPU 146 loads the compressed image data into the heap area of the working memory 140 and then compresses the compressed image data. The image data is expanded and stored in the heap area of the working memory 140. In this example, application programs, image data, and the like are stored in the external storage device 144 in the image display device 14, but as another example, the image display device 14 stores application programs, image data, and the like. You may acquire from another apparatus via a network.

  FIG. 2 is a block diagram illustrating an example of a functional configuration of the image display device 14. The image display device 14 includes a display control unit 150, an image output unit 152, an image acquisition unit 154, an image storage unit 156, a recording medium 158, and a memory management unit 160. The image storage unit 156 stores image data used by the OS and application programs.

  The display control unit 150 operates based on the OS and application program stored in the recording medium 158, and loads image data used in the application program from the image storage unit 156 to the image acquisition unit 154. Then, the display control unit 150 outputs, from the image acquisition unit 154, the image data that has reached the timing to be displayed on the display 12 among the image data loaded on the image acquisition unit 154 according to the operation of the application program. Copy to unit 152.

  The image acquisition unit 154 reads out and holds image data used by the application program being executed from the image storage unit 156. The image output unit 152 acquires image data at a timing to be displayed on the display 12 from the image acquisition unit 154 and causes the display 12 to display the image data. The memory management unit 160 manages the image data held by the image acquisition unit 154, and reduces the information amount of the image data that has passed a predetermined time since the last reference by the application program, thereby freeing up the image acquisition unit 154. Increase memory capacity.

  The recording medium 158 is a program that causes the image display device 14 to function as the display control unit 150, the image output unit 152, the image acquisition unit 154, the image storage unit 156, and the memory management unit 160, an OS, an application program, and these programs Stores setting data used in. The recording medium 158 may be, for example, an optical recording medium such as a DVD or PD, a magneto-optical recording medium such as an MD, a tape medium, a magnetic recording medium, or a semiconductor recording device. The image display device 14 reads these programs from the recording medium 158 and executes them. Further, the image display device 14 may acquire these programs via a communication line such as the Internet network. A program stored in the recording medium 158 and causing the image display device 14 to function as the display control unit 150, the image output unit 152, the image acquisition unit 154, the image storage unit 156, and the memory management unit 160 is a Java language. Is preferably described by

  FIG. 3 shows an example of the structure of data stored in the image storage unit 156. The image storage unit 156 stores the image data main body 1562 in association with an image ID 1560 for identifying each image data. By referring to the image storage unit 156, the image acquisition unit 154 can distinguish each image data. Further, the display control unit 150 identifies each image data using the image ID 1560. As a result, the display control unit 150 can instruct the image acquisition unit 154 to copy the image data that is to be displayed from the image acquisition unit 154 to the image output unit 152.

  FIG. 4 is a block diagram illustrating an example of a functional configuration of the memory management unit 160. The memory management unit 160 includes a reference information storage unit 162, an application flag storage unit 164, a non-reference period measurement unit 166, an image size detection unit 168, an information amount reduction unit 170, a reference number counting unit 172, and a reload instruction unit 174. Prepare. The application flag storage unit 164 is a reduction indicating whether or not to reduce the information amount of the image data when a predetermined time has elapsed since the last copy to the image output unit 152 after being loaded into the image acquisition unit 154 The process application flag is stored in association with an image ID for identifying image data.

  When the image data is loaded from the image storage unit 156 to the image acquisition unit 154, the non-reference period measurement unit 166 refers to the image ID of the image data loaded to the image acquisition unit 154 and corresponds to the image ID. The reduction processing application flag to be read is read from the application flag storage unit 164. When the reduction process application flag read from the application flag storage unit 164 indicates that the amount of information of the image data should be reduced, the non-reference period measurement unit 166 displays the corresponding image data on the display 12. Therefore, a non-reference period that is an elapsed time since the last copy from the image acquisition unit 154 to the image output unit 152 is measured, and the measured non-reference time is associated with the image ID of the corresponding image data and reference information. Store in the storage unit 162.

  The image size detection unit 168 calculates the image size of the image data loaded in the image acquisition unit 154, and stores the calculated image size in the reference information storage unit 162 in association with the image ID of the corresponding image data. The image size detection unit 168 calculates, for example, the data size of the image data as the image size. As another example, the image size detection unit 168 may calculate the size of the display area of the image data and the type of color as the image size.

  The reference information storage unit 162 stores the non-reference period measured by the non-reference period measurement unit 166 and the image size calculated by the image size detection unit 168 in association with the image ID. In addition, the reference information storage unit 162 displays information on what kind of information amount reduction processing has been performed on the image data, and the image data is displayed on the display 12 after the information amount is finally reduced. The number of times of copying from the image acquisition unit 154 to the image output unit 152 is further stored in association with the image ID.

  The information amount reduction unit 170 refers to the non-reference period of each image ID stored in the reference information storage unit 162, and the reference information storage unit 162 has a non-reference period that is equal to or greater than a predetermined reduction threshold. The amount of image data corresponding to the non-reference period and existing in the image acquisition unit 154 is reduced. The information amount reduction unit 170 refers to the image size in the reference information storage unit 162 and reduces the amount of information for the image data when the image size is larger than a predetermined size threshold. . The information amount reducing unit 170 reduces the information amount of the image data, for example, by reducing the color type of the image data.

As another example, the information amount reduction unit 170 may reduce the brightness and resolution of image data. When reducing the resolution of the image data, the information amount reduction unit 170 converts, for example, four adjacent pixel data into one average pixel data obtained by averaging the image information of the four pixel data. The number of pixels of the image data may be reduced by half. In this case, the information amount reduction unit 170 may convert the four pieces of pixel data 30 into one piece of pixel data 30 by averaging the luminance and color information of the four pieces of pixel data. Further, the information amount reduction unit 170, by converting the adjacent x ² pieces of pixel data in the one pixel data may reduce the number of pixels in 1 / x times. When the image data is a moving image, the information amount reduction unit 170 may reduce the information amount of the image data by reducing the number of frames of the moving image data.

  In addition, when the information amount of the image data in the image acquisition unit 154 is reduced, the information amount reduction unit 170 is the number of references stored in the reference information storage unit 162 and corresponds to the reduced image data. Clear 0. Furthermore, when the image data is loaded into the image acquisition unit 154, the information amount reduction unit 170 refers to the image ID of the image data, and whether or not the corresponding image ID exists in the reference information storage unit 162. Determine whether. When the corresponding image ID exists in the reference information storage unit 162, the information amount reduction unit 170 performs the reduction process previously applied to the image data associated with the image ID in the image acquisition unit 154. This also applies to loaded image data.

  The reference number counting unit 172 counts the number of reference times of the image data in the image acquisition unit 154 whose information amount has been reduced by the information amount reduction unit 170, and associates the counted reference number with the image ID of the corresponding image data. And stored in the reference information storage unit 162.

  The reload instruction unit 174 refers to the reference count stored in the reference information storage unit 162, and when the reference count is equal to or greater than a predetermined recovery threshold, the image data corresponding to the image ID of the reference count Are loaded from the image storage unit 156 by the image acquisition unit 154.

  FIG. 5 shows an example of the structure of data stored in the reference information storage unit 162. The reference information storage unit 162 includes a non-reference period 1622, an image size 1624, and an information amount that are elapsed times since the image data was last copied from the image acquisition unit 154 to the image output unit 152 in order to be displayed on the display 12. Information amount reduction processing is performed by the reference count 1626 and the information amount reduction unit 170, which are the number of copies from the image acquisition unit 154 to the image output unit 152 to be displayed on the display 12. The application reduction process 1628, which is information indicating whether or not it has been applied, is stored in association with the image ID 1620 for identifying the image data.

  FIG. 6 is a conceptual diagram for explaining an example of the information amount reduction process of the pixel data 30. The image data includes a plurality of pixel data 30, for example. Each pixel data 30 has padding 31, R (red) 32, G (green) 33, and B (blue) 34. The information amount reduction unit 170 refers to the non-reference period of each image ID stored in the reference information storage unit 162, and reduces the information amount of image data whose non-reference period is equal to or greater than the reduction threshold. In this case, for example, the information amount reduction unit 170 reduces the information amount of the 32-bit pixel data 30 to 16 bits by deleting the lower 3 bits of R32, G33, and B34, and adding 1-bit padding 31, for example. Reduction process 1 is performed.

  Further, when the non-reference period of the previously reduced image data exceeds the reduction threshold, the information amount reduction unit 170 deletes, for example, the lower 3 bits of R32, G33, and B34, and adds 2 bits of padding 31. By doing so, the reduction process 2 which further reduces the information amount of the 16-bit pixel data 30 to 8 bits is performed. As described above, when the non-reference period is equal to or greater than a predetermined reduction threshold, the information amount reduction unit 170 reduces the information amount of the corresponding image data in the image acquisition unit 154. Reduction of free space can be suppressed.

  The information amount reduction unit 170 refers to the image size in the reference information storage unit 162. If the image size of the image data to be reduced is equal to or larger than a predetermined size threshold, the information amount reduction unit 170 is the first reduction process. Alternatively, the information amount of the corresponding 32-bit image data may be reduced to 8 bits. As a result, a larger amount of information can be reduced as the image data has a larger image size, so that the free space in the work memory 140 can be quickly increased.

  Further, since the information amount reduction unit 170 processes each of the plurality of pixel data 30 in the image data one by one, it can be processed in the stack area of the CPU 146 or the register of the CPU 146. Therefore, as compared with the conventional configuration in which compressed image data is stored in the work memory 140, expanded at the stage of display, and written to the video memory 142, the work area for processing can be reduced. There is no need to provide a special processing area in the heap area. Accordingly, it is possible to suppress a decrease in the free area of the work memory 140.

  In addition, the information amount reduction unit 170 displays the image data with the reduced information amount because the information amount of the corresponding image data is reduced when the non-reference period of the previously reduced image data is equal to or greater than the reduction threshold. In this stage, the image data stored in the image acquisition unit 154 may be copied to the image output unit 152 as it is. Therefore, as compared with the conventional case where compressed image data is stored in the work memory 140 and the corresponding image data is expanded at the stage of display, the load on the CPU 146 at the stage of displaying the image data is small. Therefore, the image data can be displayed on the display 12 more appropriately.

  The image output unit 152 has the information amount reduced by inserting padding into each lower bit of the color information of the pixel data 30 reduced from, for example, 32 bits to 16 or 8 bits by the information amount reduction unit 170. The pixel data 30 is complemented to 32 bits. Thereby, the image output unit 152 can display the pixel data 30 with the reduced information amount on the display 12 together with the other 32-bit pixel data 30 with the color information not reduced.

As another example, if the reduced number of pixels in 1 / x times by converting the adjacent x ² pieces of pixel data in the one pixel data, the image output unit 152, the respective pixel data By copying, x ² pieces of the same pixel data are generated, and by arranging the generated same pixel data adjacent to each other, the image data in which the number of pixels is reduced to 1 / x times is obtained. The number of pixels may be displayed on the display 12.

  FIG. 7 shows an example of the structure of data stored in the application flag storage unit 164. The application flag storage unit 164 stores an application flag 1642 indicating whether or not the information amount reduction processing is applied to the corresponding image data in association with the image ID 1640 for identifying the image data. In this example, 1 is stored in the application flag 1642 when an information amount reduction process is applied to image data.

  In this way, whether or not to apply the information amount reduction processing is set for each image data, so the information amount reduction processing is not performed on the image data in which the color or resolution of the painting is a problem. Can be. Therefore, reduction processing can be performed only on image data that does not affect the service provided by the application program, and the reduction in the free space in the work memory 140 can be suppressed without causing a sense of incongruity to the user who uses the application program. Can do.

  In this example, the application flag 1642 is provided for each image data. However, as another example, the application flag 1642 may be provided for each application program. Thus, in an application program such as an image editing application program in which the quality of the image data is a problem, the information amount reduction process can be prohibited for all image data handled by the application program.

  FIG. 8 is a flowchart illustrating an example of the operation of the memory management unit 160. The operation of the memory management unit 160 described in this flowchart starts at a predetermined timing such as when the power is turned on. First, the non-reference period measuring unit 166 and the reference number counting unit 172 clear the non-reference period and the reference number stored in the reference information storage unit 162 to zero (S100).

  Next, the display control unit 150 operates according to the application program stored in the recording medium 158, and determines whether or not it is time to display the image data on the display 12 (S102). When it is not time to display the image data on the display 12 (S102: No), the non-reference period measurement unit 166 updates the non-reference period corresponding to the image data loaded in the heap area in the image acquisition unit 154 ( S124). Next, the information amount reduction unit 170 refers to the non-reference period of each image ID stored in the reference information storage unit 162, and an image ID whose non-reference period is equal to or greater than a predetermined reduction threshold is the reference information storage unit. It is determined whether it exists in 162 (S126). When an image ID equal to or greater than the reduction threshold does not exist in the reference information storage unit 162 (S126: No), the display control unit 150 performs the process shown in step 102 again. Note that the non-reference period measurement unit 166 performs the process of step 124 at a predetermined time interval such as 10 ms.

  If it is time to display the image data on the display 12 in step 102 (S102: Yes), the display control unit 150 instructs the image acquisition unit 154 to copy the image data to be displayed to the image output unit 152. The image acquisition unit 154 determines whether the corresponding image data is loaded in the heap area (S104). When the corresponding image data is not loaded into the heap area (S104: No), the image acquisition unit 154 reads the corresponding image data from the image storage unit 156 and loads it into the heap area (S106). Next, the information amount reduction unit 170 refers to the image ID of the image data loaded in the image acquisition unit 154, and determines whether or not the corresponding image ID exists in the reference information storage unit 162 (S108). . When the corresponding image ID does not exist in the reference information storage unit 162 (S108: No), the display control unit 150 performs the process shown in step 102 again.

  In step 108, when the corresponding image ID exists in the reference information storage unit 162 (S108: Yes), the information amount reduction unit 170 applies the reduction previously applied to the image data associated with the image ID. After the process is applied to the image data loaded in the image acquisition unit 154 (S110), the display control unit 150 performs the process shown in step 102 again.

  In step 104, when the corresponding image data is loaded in the heap area (S104: Yes), the reference number counting unit 172 stores the image ID and reference information storage unit of the image data loaded in the image acquisition unit 154. With reference to the application reduction process stored in 162, it is determined whether the reduction process has already been applied to the image data to be displayed (S112). When the reduction process is not applied (S112: No), the non-reference period measurement unit 166 clears the non-reference period in the reference information storage unit 162 of the corresponding image ID to zero (S112).

  In step 112, when the reduction process has already been applied (S112: Yes), the reference count unit 172 increases the reference count of the corresponding image data by 1 (S114). Then, the reload instruction unit 174 refers to the reference count in the reference information storage unit 162 and determines whether or not the corresponding image data reference count is equal to or greater than a predetermined recovery threshold (S116). When the reference count of the corresponding image data is less than the recovery threshold (S116: No), the non-reference period measurement unit 166 clears the non-reference period in the reference information storage unit 162 of the corresponding image ID to zero (S112). .

  If the reference count of the corresponding image data is greater than or equal to the recovery threshold value in step 116 (S116: Yes), the reload instruction unit 174 loads the corresponding image data from the image storage unit 156 to the image acquisition unit 154 again. Instruct. In response to the instruction from the reload instruction unit 174, the image acquisition unit 154 reloads the image data from the image storage unit 156 (S118). The reload instruction unit 174 clears the reference count stored in the reference information storage unit 162 and corresponding to the image data reloaded by the image acquisition unit 154 to zero (S120). Next, the non-reference period measurement unit 166 clears the non-reference period of the corresponding image data that is the non-reference period stored in the reference information storage unit 162 (S122), and the display control unit 150 again The process shown in step 102 is performed.

  In step 126, when an image ID equal to or greater than the reduction threshold exists in the reference information storage unit 162 (S126: Yes), the information amount reduction unit 170 stores information on the image data in the image acquisition unit 154 corresponding to the image ID. The amount is reduced (S128). In step 128, the information amount reduction unit 170 refers to the image size in the reference information storage unit 162, and if the image size of the image data to be reduced is equal to or larger than a predetermined size threshold value, the information amount reduction unit 170 performs the first reduction process. Even if there is, reduction processing 2 is performed on the corresponding image data. In this case, referring to the reference information storage unit 162, when the image size of the image data to be reduced is less than the size threshold and the previous reduction process has not been performed, for example, the image data to be reduced is 32 bits. If there is, it is preferable that the information amount reduction unit 170 reduces the 32-bit image data to 16 bits. Thus, by reducing the information amount of the image data step by step, it is possible to suppress a sense of discomfort given to the user. As another example, when the free space of the work memory 140 becomes smaller than a predetermined threshold, the information amount reduction unit 170 is a 32-bit image data when reducing the information amount of the image data. Alternatively, even 16-bit image data may be reduced to 8 bits. Thereby, the free space of the working memory 140 can be increased rapidly.

  After reducing the information amount of the image data, the information amount reduction unit 170 is an application reduction process stored in the reference information storage unit 162, and updates the corresponding image data application reduction process with the applied reduction process. (S130). Next, the reload instruction unit 174 clears the number of references stored in the reference information storage unit 162 and corresponding to the image data subjected to the reduction process to zero, and the non-reference period measurement unit 166 The non-reference period stored in the reference information storage unit 162, which is the non-reference period of the image data subjected to the reduction process, is cleared to 0 (S132), and the display control unit 150 performs the process shown in step 102 again. .

  As is clear from the above description, the memory management unit 160 of the present embodiment increases the free space of the work memory 140 by reducing the size of the data in the work memory 140, and the application program is stored in the work memory 140. When using this data, an increase in CPU processing load can be kept low.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in embodiment mentioned above. For example, in the present embodiment, the information amount reduction unit 170 acts to suppress a sense of incongruity given to the user by reducing 32-bit image data in stages by 16 bits and 8 bits. By reducing the amount of information of image data from 8 bits to 8 bits, or by reducing the color information of color image data, the image data is made black and white, so that the image data that has not been referred to for a long time is made conspicuous. It may be recognized. As a result, it is possible to prompt the user to operate the application program so that it does not handle image data that has not been referenced for a long time, and the application program can be operated efficiently according to the user's preference. Can be made.

  In the present embodiment, the information amount reduction unit 170 determines whether or not the non-reference period is equal to or greater than the reduction threshold at a predetermined time interval such as 10 ms. Although the information amount of the corresponding image data has been reduced, the present invention is not limited to this. As another example, when the image display device 14 has a garbage collection function that collects memory areas that are no longer used by a program or memory areas that are gaps between programs into a continuously usable memory area, The amount reduction unit 170 registers in the table that the information amount of the corresponding image data is reduced when the non-reference period is equal to or greater than the reduction threshold, and immediately before the garbage collection is executed, the information amount of the image data May be reduced. Here, while the CPU is executing garbage collection, the execution of the application program may be stopped, or the execution speed of the application program may be reduced. However, if the information amount reduction unit 170 performs the process of reducing the information amount of the image data immediately before performing garbage collection, the information amount reduction unit 170 reduces the information amount of the image data to newly create a free area in the memory. Since it can be generated, the possibility that the execution of garbage collection can be postponed increases. Therefore, the application program can be operated more appropriately.

It is a figure which shows an example of the hardware constitutions of the image display system 10 which concerns on one Embodiment of this invention. 3 is a block diagram illustrating an example of a functional configuration of an image display device 14. FIG. 6 is a diagram illustrating an example of the structure of data stored in an image storage unit 156. FIG. 3 is a block diagram illustrating an example of a functional configuration of a memory management unit 160. FIG. 4 is a diagram illustrating an example of a structure of data stored in a reference information storage unit 162. FIG. FIG. 6 is a conceptual diagram for explaining an example of information amount reduction processing of pixel data 30; 6 is a diagram illustrating an example of a structure of data stored in an application flag storage unit 164. FIG. 5 is a flowchart illustrating an example of the operation of the memory management unit 160.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Image display system, 12 ... Display, 14 ... Image display apparatus, 140 ... Working memory, 142 ... Video memory, 144 ... External storage device, 146 ... CPU, 148 ... bus, 150 ... display control unit, 152 ... image output unit, 154 ... image acquisition unit, 156 ... image storage unit, 1560, 1620, 1640 ... image ID, 1562 ... image data main body, 158 ... recording medium, 160 ... memory management section, 162 ... reference information storage section, 1622 ... non-reference period, 1624 ... image size, 1626 ... Reference count, 1628 ... application reduction processing, 164 ... application flag storage unit, 1642 ... application flag, 166 ... non-reference period measurement unit, 168 ... image size detection unit, 170 ... Information amount reduction unit, 172... Reference number counting unit, 174... Reload instruction unit, 30... Pixel data, 31. ..B

Claims (10)

A memory management program for managing a heap area of a working memory included in an image display device that displays image data on a display,
In the image display device,
A non-reference period measuring means for measuring a non-reference period that is an elapsed time since the image data loaded from the external storage device to the heap area of the working memory was last referred to by an application program;
Realizing an information amount reducing unit that reduces the information amount of the image data in the heap area when the non-reference period measured by the non-reference period measuring unit is equal to or greater than a predetermined reduction threshold. Feature memory management program. The memory management program according to claim 1,
The image display device further realizes image size calculation means for calculating the image size of the image data loaded in the heap area for each of the image data,
The information amount reducing means is:
When reducing the information amount of the image data in the heap area, referring to the image size calculated by the display size calculation means, the larger the image size, the larger the information amount. A memory management program characterized by reducing. The memory management program according to claim 1 or 2,
The information amount reducing means is:
A memory management program for reducing the types of colors of the image data in the heap area when the non-reference period measured by the non-reference period measuring means is equal to or greater than a predetermined reduction threshold. . The memory management program according to claim 1 or 2,
The information amount reducing means is:
A memory management program for reducing the resolution of the image data in the heap area when the non-reference period measured by the non-reference period measuring unit is equal to or greater than a predetermined reduction threshold. The memory management program according to claim 1 or 2,
The image data is moving image data,
The information amount reducing means is:
A memory management program for reducing the number of frames of the moving image data in the heap area when the non-reference period measured by the non-reference period measuring means is equal to or greater than a predetermined reduction threshold. A memory management program according to any one of claims 1 to 5,
In the image display device,
The reference number counting means for counting the number of times of reference, which is the number of times the image data whose information amount has been reduced by the application program has been referred to since the information amount of the image data was reduced last time by the information amount reducing means. When,
When the reference count counted by the reference count counting unit is equal to or greater than a predetermined recovery threshold, the image data whose reference count is equal to or greater than the recovery threshold is transferred from the external storage device to the heap area. A memory management program characterized by further realizing a reloading means for reloading. A memory management program according to any one of claims 1 to 6,
In the terminal device,
Further realized is a reduction processing flag storage means for storing a reduction processing flag indicating whether or not the image data reduction processing is performed by the information amount reduction means in association with application program identification information for identifying each of the application programs. Let
The information amount reducing means is:
Referring to the reduction processing flag stored in the reduction processing flag storage means, performing the reduction processing on the image data handled by the application program indicated to perform the reduction processing of the image data. Feature memory management program. A memory management program according to any one of claims 1 to 7,
In the terminal device,
When the information amount reducing unit reduces the information amount of the image data, the reduction information indicating that the information amount is reduced is associated with the image identification information for identifying the image data with the reduced information amount. Further realize the reduction information storage means to store,
The information amount reducing means is:
Based on the non-reference period measured by the non-reference period measurement means when the image data previously loaded in the heap area is loaded from the external storage device into the heap area again by the application program. Prior to reducing the amount of image information, the reduction information stored in the reduction information storage means was referred to and the same reduction process as the previous reduction process applied to the image data was loaded again. A memory management program applied to the image data. A memory management program according to any one of claims 1 to 7,
A memory management program characterized in that a code of an application program is described in Java language. An image display device for displaying image data on a display,
An external storage unit for storing a plurality of compressed image data;
A working memory that expands and holds the loaded image data when any of the plurality of image data stored in the external storage unit is loaded;
Operates based on an application program, and loads the compressed image data from the external storage unit to the heap area of the working memory according to an instruction of the application program, and loads the compressed image data loaded to the heap A display control unit that expands in the area and displays the image data expanded in the heap area on the display according to an instruction of the application program;
A memory management unit for managing the image data in the heap area;
The memory management unit
A non-reference period measurement unit that measures a non-reference period, which is an elapsed time since the display control unit was last referred to after the image data was loaded from the external storage device into the heap area by the display control unit. When,
An information amount reduction unit that reduces the information amount of the image data in the heap area when the non-reference period measured by the non-reference period measurement unit is equal to or greater than a predetermined reduction threshold. It is an image display device.

Images