JP2004295564A - File storage device, file storage method, and file storage program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To store data of high quality without reducing the number of storable files by enhancing the using efficiency of a memory. <P>SOLUTION: A JPEG processing part 17 compresses original image data at a basic compression rate, and acquires the file size of the compressed image data. A CPU 11 calculates the actual occupation size occupying a flash memory 18 in the storage of the compressed image data from a cluster size and the file size, and determines a corrected compression rate from the value of the change rate of compression file size in reference to a correspondence table in which the compression rate is preliminarily conformed to the change rate of compression file size. The JPEG processing part 17 compresses the original image data at the corrected compression rate, and stores the compressed image data in the flash memory 18. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a file storage device, a file storage method, and a file storage program for compressing and storing a file on a recording medium having a predetermined minimum recording unit.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a digital camera or a mobile phone having a photographing function, an image file is usually compressed and then stored in a recording medium such as a memory. For example, in a digital camera or the like, if the user selects an image quality for saving a captured image from among several image quality, the image captured at the selected image quality (compression ratio) is compressed until the setting is changed. And stored in a recording medium such as a memory. In a mobile phone or the like having a photographing function, compression is performed at a preset fixed compression ratio, and then stored in a recording medium such as a memory (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP 2000-270294 A
[0004]
[Problems to be solved by the invention]
By the way, a memory for storing a file is managed by a file system. Generally, in a file system, memory is managed in units of clusters. The cluster size has a unique value for each system. For example, in the case of a FAT16 file system, the cluster size is 16 Kbytes. One file consumes at least this cluster capacity. For example, if one cluster is 16 Kbytes, storing 1 byte of data consumes 16 Kbytes. That is, the area other than 1 byte is not used. For example, in the case of a mobile phone, since there is a large amount of data of 4 to 7 Kbytes, there is a useless area in the cluster, and the memory use efficiency is poor.
[0005]
As described above, in the related art, the compression is performed without considering the capacity necessary for storing the file (the amount of the occupied area = the cluster size actually used), so that an unused area is generated at the end of the storage area. Was. Since this unused area is occupied by the saved image file, it cannot be used for storing other data, and becomes a useless area, thus deteriorating the memory use efficiency.
[0006]
Therefore, an object of the present invention is to provide a file storage device, a file storage method, and a file storage program that can store high-quality data without increasing the use efficiency of a memory and reducing the number of storable files. I do.
[0007]
[Means for Solving the Problems]
To achieve the above object, a file storage device according to the first aspect of the present invention is a file storage device for compressing and storing a file on a recording medium having a predetermined minimum recording unit. Means, size detection means for detecting the size of the file compressed by the compression means, occupancy size detection means for detecting the occupation size when the file compressed by the compression means is stored in the recording medium, Correction compression in which the unused area in the minimum recording unit on the recording medium is minimized based on the size of the compressed file detected by the size detection means and the occupation size of the compressed file detected by the occupation size detection means. Compression parameter determining means for determining a parameter; Based on the determined correction compression parameters, characterized by comprising a storage control unit for storing the re-compressed to a recording medium the file by the compression means.
[0008]
In a preferred embodiment, in the file storage device according to the first aspect, the compression parameter may be a compression ratio.
[0009]
In a preferred embodiment, for example, in the file storage device according to the first aspect, the compression parameter may be an encoding method.
[0010]
In a preferred embodiment, in the file storage device according to the first aspect, the compression parameter may be a sampling rate.
[0011]
Further, as a preferred mode, for example, in the file storage device according to claim 1, the compression parameter and the correction compression parameter are a size of the file, and a file resize for resizing the file. Means for resizing the file based on the corrected compression parameter by the file resizing means prior to compression of the file by the compression means, and resizing the file resized by the compression means. It may be compressed and stored in a recording medium.
[0012]
Further, as a preferable mode, for example, in the file storage device according to claim 1, the compression parameter and the correction compression parameter are the file format of the file, and the file format of the file is Comprising a file format conversion means for converting, the storage control means, prior to compression of the file by the compression means, after converting the file format of the file by the file format conversion means based on the corrected compression parameter, The file whose file format has been converted by the compression means may be recompressed and stored in a recording medium.
[0013]
In a preferred embodiment, the compression parameter and the correction compression parameter are additional information to be added to the file, and the storage control means May be recompressed by the compression means in a state where additional information based on the corrected compression parameter is added, and stored in a recording medium.
[0014]
According to another aspect of the present invention, there is provided a file storage method for compressing and storing a file on a recording medium having a predetermined minimum recording unit. Then, based on the size of the compressed file and the occupied size when the compressed file is stored on the recording medium, a correction compression parameter that minimizes an unused area in a minimum recording unit on the recording medium is determined. The file is recompressed based on the corrected compression parameter and stored in a recording medium.
[0015]
Further, as a preferable mode, for example, in the file storage device according to claim 7, the compression parameter may be a compression ratio.
[0016]
Further, as a preferable mode, for example, in the file storage device according to claim 7, the compression parameter may be an encoding method.
[0017]
Further, as a preferred mode, for example, in the file storage device according to claim 7, the compression parameter may be a sampling rate.
[0018]
As a preferred mode, for example, in the file storage method according to the twelfth aspect, the compression parameter and the correction compression parameter are the size of the file, and are set prior to the compression of the file. After resizing the file based on the corrected compression parameter, the resized file may be recompressed and stored on a recording medium.
[0019]
As a preferred mode, in the file storage method according to claim 7, for example, the compression parameter and the correction compression parameter are in a file format of the file, and the compression parameter and the correction compression parameter are set prior to the compression of the file. Then, after converting the file format of the file based on the corrected compression parameter, the file in which the file format has been converted may be recompressed and stored in a recording medium.
[0020]
As a preferred mode, in the file storage method according to claim 7, for example, the compression parameter and the correction compression parameter are additional information added to the file, and the correction compression parameter May be recompressed in a state where the additional information based on the information is added and stored in a recording medium.
[0021]
In order to achieve the above object, a file storage program according to a fifteenth aspect of the present invention is a file storage program for compressing and storing a file on a recording medium having a predetermined minimum recording unit. Based on the size of the compressed file and the occupied size when the compressed file is stored on the recording medium, the unused area in the minimum recording unit on the recording medium is minimized. Determining a corrected compression parameter, and recompressing the file based on the corrected compression parameter and storing the compressed file in a recording medium.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described as an example in which the present invention is applied to a digital camera with reference to the drawings.
[0023]
A. First embodiment
A-1. Configuration of the first embodiment
FIG. 1 is a block diagram showing the configuration of the digital camera according to the first embodiment of the present invention. In the figure, a lens 1 is a so-called photographic lens, which optically photographs a subject and forms an image on a CCD 2. The CCD 2 is a device having a MOS (metal-oxide semiconductor) structure for transferring electric charges in an array, is driven by a timing generator (TG) 3 and a vertical driver 4, and outputs a photoelectric conversion output for one screen at regular intervals. . The timing generator 3 and the vertical driver 4 generate a timing signal required for reading the CCD 2. The sample hold circuit (S / H) 5 samples the time-series analog signal read from the CCD 2 at a frequency suitable for the resolution of the CCD 2. The A / D converter 6 converts the sampled signal into a digital signal (Bayer data).
[0024]
The color process circuit 7 performs a color process for generating a luminance / color difference multiplex signal (hereinafter, referred to as a YUV signal) from the output of the A / D converter 6. In the color process, the Bayer data is converted into R, G, B data, and further converted into digital luminance and color difference multiplex signals (Y, Cb, Cr data).
[0025]
The DMA controller 8 performs data transfer between the color process circuit 7 and the DRAM 10 (precisely, the DRAM interface 9) without the intervention of the CPU 11, and performs a so-called direct memory access (DMA: direct memory access). It is what you do. The DMA controller 8 writes the Y, Cb, and Cr data outputs of the color process circuit 7 to the buffer inside the DMA controller 8 once by using the synchronization signal, the memory write enable, and the clock output of the color process circuit 7 as well. DMA transfer is performed to the DRAM 10 via the interface (DRAM I / F) 9. The DRAM interface 9 has a signal interface between the DRAM 10 and the DMA controller 8 and a signal interface between the DRAM 10 and the bus. The DRAM 10 stores image data (Y, Cb, Cr data) DMA-transferred from the DMA controller 8 via the DRAM interface 9.
[0026]
The CPU 11 executes a predetermined program recorded in the program ROM 20 to centrally control the operation of the camera, and includes an execution button such as a main switch, a recording / playback mode switch, a function selection key, and a shutter key. The operation unit 16 is connected. In the recording mode, the mode program is loaded, and in the reproduction mode, the mode program is loaded from the program ROM 20 to the RAM inside the CPU 11 and executed. After completing the DMA transfer of the image data (Y, Cb, Cr data) to the DRAM 10, the CPU 11 reads the image data (Y, Cb, Cr data) from the DRAM 10 via the DRAM interface 9, and controls the VRAM controller 12. Write to the VRAM 13 via the
[0027]
When the shutter key is depressed, the CPU 11 transfers the Y, Cb, and Cr data for one frame written in the DRAM 10 to each of the Y, Cb, and Cr components via the DRAM interface 9 in the recording and saving state. Is read out for each MCU block composed of 16 × 16 pixels obtained by dividing one frame into 80 × 60 blocks (“0” to “4799”) in MCU units, and further inserting an MCU block of an image to be added into JPEG. Send to processing unit 17. The image data sent to the JPEG processing unit 17 is compressed through processes such as DCT conversion, quantization, and encoding. The CPU 11 adds header information to the compressed image data and writes the image data to the flash memory 18 which is a nonvolatile memory. The header information includes information on an image and the like.
[0028]
In the DCT transform, the data of the MCU block (hereinafter simply referred to as MCU data) is defined as a set of luminance component data of a block composed of predetermined pixels and color difference component data of a block composed of predetermined pixels. Is converted to a DCT coefficient indicating the magnitude of the frequency component. When the compression processing of the Y, Cb, and Cr data for one frame and writing of all the compressed data to the flash memory 18 are completed, the CPU 11 activates the path from the CCD 2 to the DRAM 10 again.
[0029]
The VRAM controller 12 controls data transfer between the VRAM 13 and the bus, and between the VRAM 13 and the digital video encoder 14. Control the reading from.
[0030]
The VRAM 13 is a so-called video RAM, and when a preview image is written, the preview image is sent to the display device 15 via the digital video encoder 14 and displayed. The video RAM has two ports for writing and reading, so that writing and reading of an image can be performed simultaneously and in parallel.
[0031]
A digital video encoder (hereinafter, simply referred to as a video encoder) 14 periodically reads the image data (Y, Cb, Cr data) from the VRAM 13 via the VRAM controller 12 and converts a video signal based on the image data. Generated and output to the display device 15. As a result, a through image based on the image information currently taken in from the CCD 2 is displayed on the display device 15 in the recording mode. The display device 15 is a small liquid crystal panel of about several inches and having, for example, 279 × 220 pixels and attached to the back of the camera body.
[0032]
The JPEG processing unit 17 is a part that performs JPEG compression and decompression. JPEG compression parameters are provided from the CPU 11 each time compression processing is performed. The JPEG processing unit 17 is preferably implemented by dedicated hardware in terms of processing speed, but can be implemented by the CPU 11 as software.
[0033]
The flash memory 18 refers to a rewritable read-only memory (PROM) that can be electrically rewritten by erasing the contents of all bits (or blocks) in a programmable read only memory (PROM). The flash memory 18 may be a fixed type that cannot be removed from the camera body, or may be a removable type such as a card type or a package type. The flash memory 18 must be initialized (formatted) to a predetermined cluster size in a predetermined format, whether it is a built-in type or a removable type. The details of the cluster size will be described later. In the initialized flash memory 18, a number of images corresponding to the storage capacity can be recorded.
[0034]
A network connection interface (network connection I / F) 19 connects to a server 100 on the Internet 101 according to a specified URL according to a packet communication protocol of the mobile phone 104 as necessary, and acquires an HTML file from the server 100. Is what you do. In the first embodiment, as shown in FIG. 1, the mobile phone 104 is connected to the network connection interface 19 and connected to the Internet 101 via the mobile phone 104. However, the present invention is not limited to this. A detachable communication module may be used, or the communication function of the mobile phone 104 may be incorporated in the digital still camera itself.
[0035]
Further, as shown in FIG. 2, the program ROM 20 stores a correspondence table in which the compression rate and the change rate of the compressed file size are associated in advance. The JPEG processing unit 17 compresses the original image data at a basic compression ratio. The CPU 11 obtains the change rate of the compressed file size from the size of the compressed image data and the actual size occupying the memory when storing the compressed image data, and calculates the correspondence table according to the change rate of the compressed file size. To find the corrected compression ratio. Then, the JPEG processing unit 17 recompresses the original image data according to the corrected compression ratio, and stores the compressed image data in the flash memory 18.
[0036]
In the digital camera, when storing a captured image, the image data is compressed and then stored in the flash memory 18. For example, the image format called JPEG can exclusively control the image quality and the file capacity by the compression ratio. If the compression ratio is reduced to improve the image quality, the file size increases, so the number of storable files decreases.If the compression ratio is increased to increase the number of storable files, the image quality decreases. . Usually, the user sets a desired image quality, that is, a compression ratio in consideration of the image quality and the number of shots.
[0037]
In the first embodiment, when the image data is compressed, when the image data is compressed at a preset compression ratio and stored in the flash memory 18, the image data is compressed to the full cluster capacity so that an unused area does not occur. The compression ratio is reduced for use. As a result, the use efficiency of the flash memory 18 is improved, and the image quality is improved despite the same number of images that can be shot. In the following description, the data format of the original image is a YUV format. The compression method is a JPEG baseline.
[0038]
Usually, the cluster size is considered to be obvious, but if unknown, it can be confirmed by the following procedure.
[0039]
1) Check available remaining capacity
2) Writing dummy data (1 byte)
3) Check available remaining capacity
4) The difference between the above 1) and 3) is defined as the cluster size.
5) Erase dummy data.
[0040]
A-2. Operation of the first embodiment
Next, the operation of the digital camera according to the first embodiment will be described. Here, FIG. 3 is a flowchart for explaining the image data saving operation of the digital camera according to the first embodiment. FIG. 4 is a conceptual diagram illustrating an image compression operation of the digital camera according to the first embodiment.
[0041]
First, the original image data is compressed at the basic compression ratio (step S10). Next, the size of the compressed image data (hereinafter, file size) is obtained (step S12). Incidentally, in the compression of image data, the finally obtained file size differs depending on the content of the image data even with the same compression ratio. Next, the actual size (hereinafter, occupied size) occupying the flash memory 18 at the time of storing the compressed image data is calculated from the cluster size and the file size (step S14). The file size includes, in addition to the compressed image data, information necessary for generating a file such as information (table) necessary for the image data.
[0042]
Number of occupied clusters = ((file size) ÷ (cluster size)) + 1
Occupancy size = number of occupied clusters x cluster size
However, when (file size) = (cluster size × n), there is no +1.
[0043]
Next, with reference to a correspondence table (FIG. 2) in which the compression rate and the change rate of the compressed file size are associated in advance, the correction is made from the value of (occupancy size) / (file size) = change rate of the compressed file size. A compression ratio (hereinafter, a corrected compression ratio) is obtained and set (step S16).
[0044]
Next, it is determined whether or not the corrected compression rate is the same as the basic compression rate (step S18). If the two compression rates are different, the original image data is compressed again at the corrected compression rate (step S18). S20). On the other hand, if the two compression ratios are the same, the process proceeds to step S22 without performing compression again.
[0045]
Next, it is determined whether or not the file size of the compressed image data is larger than the occupation size (step S22). If the file size is smaller than the occupation size, the compressed image data is stored in the flash memory 18 (step S24). ). On the other hand, if the file size has become larger than the occupied size, the process returns to step S16, the compression ratio is readjusted, and the above-described processing is repeated.
[0046]
According to the above-described first embodiment, as shown in FIG. 4, since the compression ratio tends to be lower than that of the related art, the recompressed image data has a higher image quality than an image without adjusting the compression ratio. There is an advantage that is improved. Also, since the occupation size is not changed, the number of storable images can be maintained the same. Further, since there is no unused area in the cluster, the use efficiency of the flash memory 18 can be improved.
[0047]
In the first embodiment described above, the image format is described as JPEG, but other formats, such as PNG, GIF, and TIFF, may be used. Further, in the first embodiment, the description has been made on the assumption that image files are compressed. However, all compressed files (MP3, MPEG, etc.) including images may be used. Further, although the entire image is compressed to determine the file size, a part of the image may be compressed to determine the file size. Further, although the compression format is the JPEG baseline, other formats (JPEG progressive, JPEG2000) may be used.
[0048]
B. Second embodiment
Next, a second embodiment of the present invention will be described. The configuration of the digital camera is the same as that of FIG. In the second embodiment, an encoding method that matches the occupied size of image data obtained by compressing original image data at a basic compression ratio is selected. As the encoding method, a JPEG2000 method (reference encoding method), a JPEG paceline method, and a JPEG progressive method are prepared. Therefore, as shown in FIG. 5, a correspondence table in which the encoding method and the change rate of the compressed file size are associated with each other is stored in the program ROM 20 in advance.
[0049]
Next, the operation of the second embodiment will be described. Here, FIG. 6 is a flowchart for explaining the operation of the second embodiment. First, the original image data is compressed by the basic encoding method, that is, JPEG2000 (step S30). Next, the size of the compressed image data (hereinafter, file size) is obtained (step S32). Next, an actual size occupying the flash memory 18 when saving the compressed image data (hereinafter, occupied size) is calculated from the cluster size and the file size (step S34).
[0050]
Next, with reference to a correspondence table (FIG. 5) in which the encoding method and the change rate of the compressed file size are associated in advance, an appropriate value is obtained from the value of (occupancy size) / (file size) = change rate of the compressed file size. An appropriate encoding method is selected (step S36). Next, the original image data is compressed again by the newly selected encoding method (step S38). Next, it is determined whether or not the file size of the compressed image data is larger than the occupied size (step S40). If the file size is smaller than the occupied size, the compressed image data is stored in the flash memory 18 (step S42). ). On the other hand, if the file size has become larger than the occupied size, the process returns to step S36, re-selects the encoding method, and repeats the above processing.
[0051]
In the above-described second embodiment, since the encoding method is changed from the JPEG2000 method to the JPEG paceline method or the JPEG progressive method, there are effects of shortening the compression and decompression processing time and increasing the drawing speed. Further, since the occupation size is not changed, the number of storable images can be kept the same. Further, since there is no unused area in the cluster, the use efficiency of the flash memory 18 can be improved.
[0052]
In the second embodiment described above, the basic encoding method is described as JPEG2000, but another encoding method (JPEG baseline, JPEG progressive) may be used. Although the image format is JPEG2000, other formats (PNG, GIF, TIFF) may be used. In addition, although the description has been given as the compression of the image file, all the compressed files including the image may be used. Further, although the entire image is compressed to determine the file size, a part of the image may be compressed to determine the file size.
[0053]
C. Third embodiment
Next, a third embodiment of the present invention will be described. The configuration of the digital camera is the same as that of FIG. In the third embodiment, the sampling rate is selected according to the occupied size of the image data obtained by compressing the original image data at the basic sub-sampling rate. As the subsampling rates, 4: 2: 0 (reference subsampling rate), 4: 2: 2, and 4: 4: 4 are prepared. Therefore, as shown in FIG. 7, a correspondence table in which the sub-sampling rate and the change rate of the compressed file size are associated in advance is stored in the program ROM 20.
[0054]
Next, the operation of the third embodiment will be described. Here, FIG. 8 is a flowchart for explaining the operation of the third embodiment. First, the original image data is compressed at 4: 2: 0 (reference subsampling rate) (step S50). Next, the size of the compressed image data (hereinafter, file size) is obtained (step S52). Next, an actual size occupying the flash memory 18 when storing the compressed image data (hereinafter, occupied size) is calculated from the cluster size and the file size (step S54).
[0055]
Next, referring to a correspondence table (FIG. 7) in which the sub-sampling rate and the change rate of the compressed file size are associated in advance, an appropriate value is obtained from the value of (occupancy size) / (file size) = change rate of the compressed file size. An appropriate sub-sampling rate is selected (step S56). Next, the original image data is compressed again at the newly selected sub-sampling rate (step S58). Next, it is determined whether or not the file size of the compressed image data is larger than the occupied size (step S60). If the file size is smaller than the occupied size, the compressed image data is stored in the flash memory 18 (step S62). ). On the other hand, if the file size has become larger than the occupied size, the process returns to step S46, reselects the sub-sampling rate, and repeats the above-described processing.
[0056]
In the third embodiment described above, since the subsampling rate is changed from 4: 2: 0 (reference subsampling rate) to 4: 2: 2 or 4: 4: 4, image information is increased. This has the effect of improving image quality. Further, since the occupation size is not changed, the number of storable images can be kept the same. Further, since there is no unused area in the cluster, the use efficiency of the flash memory 18 can be improved.
[0057]
In the above-described third embodiment, the original image data is described as YUV data. However, another color space (RGB, YCMK, YcbCr, or the like) may be used. Although the image format has been described as JPEG, another format (PNG, GIF, TIFF) may be used. Although the compression format is the JPEG baseline, other formats (JPEG progressive, JPEG2000, etc.) may be used. Further, the subsampling of the image is adjusted as a parameter, but the sampling rate of audio (such as MP3) may be used. Also, the subsampling rate has been described as being limited to three types (4: 4: 4, 4: 2: 2, 4: 2: 0), but other ratios (4: 1: 1, 6: 1: 1). Etc.).
[0058]
D. Fourth embodiment
Next, a fourth embodiment of the present invention will be described. The configuration of the digital camera is the same as that of FIG. In the fourth embodiment, an image size that matches the occupied size of image data obtained by compressing original image data with the basic image size is selected. As the image size, VGA (640 × 480: basic image size), SVGA (800 × 600) and XGA (1024 × 768) are prepared. Therefore, as shown in FIG. 9, a correspondence table in which the image size and the change rate of the compressed file size are associated in advance is stored in the program ROM 20.
[0059]
Next, the operation of the fourth embodiment will be described. Here, FIG. 10 is a flowchart for explaining the operation of the fourth embodiment. First, the original image data is converted into VGA (basic image size: 640 × 480) and compressed with a JPEG baseline (step S70). Next, the size of the compressed image data (hereinafter, file size) is obtained (step S72). Next, an actual size occupying the flash memory 18 at the time of storing the compressed image data (hereinafter, occupied size) is calculated from the cluster size and the file size (step S74).
[0060]
Next, referring to a correspondence table (FIG. 9) in which the image size and the change rate of the compressed file size are associated in advance, an appropriate value is obtained from the value of (occupancy size) / (file size) = change rate of the compressed file size. An image size is selected (step S76). Next, the original image data is converted to a newly selected image size and compressed again (step S78). Next, it is determined whether or not the file size of the compressed image data is larger than the occupation size (step S80). If the file size is smaller than the occupation size, the compressed image data is stored in the flash memory 18 (step S82). ). On the other hand, if the file size has become larger than the occupied size, the process returns to step S76, reselects the image size, and repeats the above processing.
[0061]
In the above-described fourth embodiment, since the image size is changed before compression, the image quality is improved as compared with the size change after compression. Further, since the occupied size is not changed, the number of storable images can be maintained the same, and the use efficiency of the flash memory 18 can be increased.
[0062]
In the above-described fourth embodiment, the original image data is described as YUV data. However, another color space (RGB, YCMK, YcbCr, or the like) may be used. Although the image format has been described as JPEG, another format (PNG, GIF, TIFF) may be used. Although the compression format is the JPEG baseline, other formats (JPEG progressive, JPEG2000, etc.) may be used. Further, although the entire image is compressed to determine the file size, a part of the image may be compressed to determine the file size.
[0063]
E. FIG. Fifth embodiment
Next, a fifth embodiment of the present invention will be described. The configuration of the digital camera is the same as that of FIG. In the fifth embodiment, an appropriate file format is selected based on the occupied size of the image data obtained by compressing the original image data in the basic file format (JPEG) so that there is no unused area in the cluster of the memory. The original image data is compressed and stored in the selected file format. JPEG (basic file format), TIFF and BMP are prepared as file formats. Therefore, as shown in FIG. 11, a correspondence table in which the file format and the change rate of the compressed file size are associated in advance is stored in the program ROM 20.
[0064]
Next, the operation of the fifth embodiment will be described. Here, FIG. 12 is a flowchart for explaining the operation of the fifth embodiment. First, the original image data is compressed in JPEG (basic file format) (step S90). Next, the size of the compressed image data (hereinafter, file size) is obtained (step S92). Next, an actual size (hereinafter, occupied size) occupying the flash memory 18 when the compressed image data is stored is calculated from the cluster size and the file size (step S94).
[0065]
Next, referring to a correspondence table (FIG. 11) in which the file format and the change rate of the compressed file size are associated in advance, an appropriate value is obtained from the value of (occupancy size) / (file size) = change rate of the compressed file size. A file format is selected (step S96). Next, the original image data is converted into a newly selected file format (step S98). At this time, if the file format requires compression, compression is performed. Next, it is determined whether or not the file size of the compressed image data is larger than the occupied size (step S100). If the file size is smaller than the occupied size, the compressed image data is stored in the flash memory 18 (step S102). ). On the other hand, if the file size has become larger than the occupation size, the process returns to step S96, reselects the file format, and repeats the above processing.
[0066]
In the fifth embodiment described above, the file format is changed from a format with compression to a non-compression format, so that the image is not degraded and the image quality is improved. In addition, since the compression processing is eliminated, there is an effect that image processing and drawing processing are speeded up. Also, since the occupation size is not changed, the number of storable images can be maintained the same. Further, since there is no unused area in the cluster, the use efficiency of the flash memory 18 can be improved.
[0067]
In the above-described fifth embodiment, the original image data is described as YUV data. However, another color space (RGB, YCMK, YcbCr, etc.) may be used. Also, the image format has been described as JPEG, but other formats (PNG, GIF, etc.) may be used. Further, the converted image format is JPEG, but another format may be used. Further, although the description has been made as conversion of an image file, all file formats including an image (MPEG, MP3, etc.) may be used.
[0068]
F. Sixth embodiment
Next, a sixth embodiment of the present invention will be described. The configuration of the digital camera is the same as that of FIG. In the sixth embodiment, appropriate additional information is set based on the occupied size of image data obtained by compressing original image data in a predetermined compression format (JPEG baseline) so that unused areas in a cluster of the memory are reduced as much as possible. Is selected, and the selected additional information is compressed and stored in a state of being added to the original image data. As additional information, no addition (basic method), position information and thumbnail images are prepared. Therefore, as shown in FIG. 13, a correspondence table in which the additional information and the change rate of the compressed file size are associated in advance is stored in the program ROM 20.
[0069]
Next, the operation of the sixth embodiment will be described. Here, FIG. 14 is a flowchart for explaining the operation of the sixth embodiment. First, the original image data is compressed by JPEG (step S110). Next, the size of the compressed image data (hereinafter, file size) is obtained (step S112). Next, an actual size occupying the flash memory 18 when storing the compressed image data (hereinafter, occupied size) is calculated from the cluster size and the file size (step S114).
[0070]
Next, by referring to a correspondence table (FIG. 13) in which the additional information is previously associated with the change rate of the compressed file size, an appropriate value is obtained from the value of (occupied size) / (file size) = change rate of the compressed file size. The additional information is selected (step S116). Next, compression is performed with the selected additional information added to the original image data (step S118). Next, it is determined whether or not the file size of the compressed image data is larger than the occupation size (step S120). If the file size is smaller than the occupation size, the compressed image data is stored in the flash memory 18 (step S122). ). On the other hand, if the file size has become larger than the occupied size, the process returns to step S116, reselects additional information, and repeats the above-described processing.
[0071]
In the sixth embodiment described above, since the image information and the additional information exist in one file, the relation between the image and the additional information can be easily determined, and a new service using the image and the additional information can be easily obtained. Can be provided. Also, since the occupation size is not changed, the number of storable images can be maintained the same. Further, since there is no unused area in the cluster, the use efficiency of the flash memory 18 can be improved.
[0072]
In the above-described sixth embodiment, the original image data is described as YUV data. However, another color space (RGB, YCMK, YcbCr, or the like) may be used. Although the image format has been described as JPEG, other formats (PNG, GIF, TIFF, etc.) may be used. Although the compression format is the JPEG baseline, other formats (JPEG progressive, JPEG2000, etc.) may be used. Further, although the description has been made on the assumption that image files are compressed, all files including uncompressed image files may be used. Further, although the description has been made assuming that the additional information is one, a plurality of additional information may be used. The addition of additional information is a point, but may be combined with another embodiment (for example, the sixth embodiment is performed after the first embodiment). Further, the position information and the thumbnail image are used as the additional information, but other information may be used.
[0073]
G. FIG. Seventh embodiment
Next, a seventh embodiment of the present invention will be described. In the above-described first to sixth embodiments, the occupation size is calculated by compressing the actual image data. However, the size may be set as an upper limit to the size in which the free clusters of the file system are physically continuous. . In the above-described first to sixth embodiments, a physically continuous cluster of the occupied size may be searched for and stored.
[0074]
In the above-described seventh embodiment, clusters for storing files are physically continuous, so that writing and reading of files can be performed at high speed.
[0075]
In the above-described seventh embodiment, physically continuous clusters are searched, but physically continuous clusters may be prepared in advance.
[0076]
In the first to seventh embodiments, only the digital camera has been described. However, it is needless to say that the present invention can be applied to a mobile phone having a photographing function, a personal computer handling various types of compressed data, and the like.
[0077]
【The invention's effect】
According to the first aspect of the present invention, the file is compressed by the compression means with a predetermined compression parameter, the size of the compressed file is detected by the size detection means, and the compressed file is detected by the occupation size detection means. An occupied size when the data is stored in the recording medium is detected, and an unused area in a minimum recording unit in the recording medium is determined by a compression parameter determining unit based on the size of the compressed file and the occupied size of the compressed file. Is determined and the storage control means recompresses the file by the compression means based on the determined correction compression parameter and saves the file on the recording medium. It is possible to reduce the unused area in the minimum recording unit and without reducing the number of storable files, Advantage that it is possible to store the data of quality.
[0078]
According to the second aspect of the present invention, since the compression parameter is a compression ratio, an unused area in a minimum recording unit of a storage medium can be reduced, and the number of storable files can be reduced. The advantage is that high quality data can be stored.
[0079]
According to the third aspect of the present invention, since the compression parameter is an encoding method, an unused area in a minimum recording unit of a storage medium can be reduced, and the number of storable files can be reduced. The advantage is that high quality data can be stored.
[0080]
According to the fourth aspect of the present invention, since the compression parameter is a sampling rate, an unused area in a minimum recording unit of a storage medium can be reduced, and the number of storable files can be reduced. The advantage is that high quality data can be stored.
[0081]
According to the fifth aspect of the present invention, the compression parameter and the correction compression parameter are set to the size of the file, and the file is resized by the file resizing unit by the storage control unit before the file is compressed by the compression unit. After the file is resized based on the corrected compression parameter, the file resized by the compression unit is recompressed and stored in the recording medium, so that the unused area in the minimum recording unit of the storage medium is reduced. The advantage is that high-quality data can be stored without reducing the number of files that can be stored.
[0082]
According to the invention of claim 6, the compression parameter and the corrected compression parameter are set to the file format of the file, and the storage control unit performs the file format conversion before the file is compressed by the compression unit. After the file format of the file is converted based on the corrected compression parameter, the file whose file format has been converted by the compression unit is recompressed and stored in the recording medium. This is advantageous in that high-quality data can be stored without reducing the unused area of the data and without reducing the number of files that can be stored.
[0083]
According to the invention described in claim 7, the compression parameter and the corrected compression parameter are set as additional information to be added to the file, and the storage control unit adds the additional information based on the corrected compression parameter to the file. Since the data is recompressed by the compression means and stored on the recording medium, the unused area in the minimum recording unit of the storage medium can be reduced, and high-quality data can be stored without reducing the number of storable files. The advantage is that it can be stored.
[0084]
According to the invention described in claim 8, the file is compressed with a predetermined compression parameter, and the recording medium is compressed based on the size of the compressed file and the occupied size when the compressed file is stored in the recording medium. Since the correction compression parameter that minimizes the unused area in the minimum recording unit is determined, and based on the correction compression parameter, the file is recompressed and stored in the recording medium. The advantage is that unused areas in a recording unit can be reduced, and high-quality data can be stored without reducing the number of storable files.
[0085]
According to the ninth aspect of the present invention, since the compression parameter is a compression ratio, an unused area in a minimum recording unit of a storage medium can be reduced, and the number of storable files can be reduced. The advantage is that high quality data can be stored.
[0086]
According to the tenth aspect of the present invention, since the compression parameter is an encoding method, an unused area in a minimum recording unit of a storage medium can be reduced, and the number of storable files can be reduced. The advantage is that high quality data can be stored.
[0087]
According to the eleventh aspect of the present invention, since the compression parameter is a sampling rate, an unused area in a minimum recording unit of a storage medium can be reduced, and the number of storable files can be reduced. The advantage is that high quality data can be stored.
[0088]
According to the twelfth aspect of the present invention, the compression parameter and the correction compression parameter are set to the size of the file, and the file is resized based on the correction compression parameter before the file is compressed. The compressed file is recompressed and stored on the recording medium, so the unused area in the minimum recording unit of the storage medium can be reduced, and high-quality data can be stored without reducing the number of storable files. The advantage is that it can be stored.
[0089]
According to the thirteenth aspect of the present invention, the compression parameter and the correction compression parameter are set to the file format of the file, and the file format of the file is converted based on the correction compression parameter prior to the compression of the file. After that, the file whose format has been converted is recompressed and saved on the recording medium, so that the unused area in the minimum recording unit of the storage medium can be reduced and the number of storable files can be reduced. And high quality data can be stored.
[0090]
According to the fourteenth aspect of the present invention, the compression parameter and the corrected compression parameter are set as additional information to be added to the file, and are re-compressed in a state where the additional information based on the corrected compression parameter is added to the recording medium. Since the data is stored, the unused area in the minimum recording unit of the storage medium can be reduced, and the high-quality data can be stored without reducing the number of files that can be stored. .
[0091]
According to the invention of claim 15, a step of compressing a file with a predetermined compression parameter, a size of the compressed file, and an occupied size when the compressed file is stored in the recording medium. Determining a correction compression parameter that minimizes an unused area in a minimum recording unit on the recording medium based on the correction compression parameter; and recompressing the file based on the correction compression parameter and storing the file on the recording medium. And causing the computer to execute the steps, the unused area in the minimum recording unit of the storage medium can be reduced, and high-quality data can be stored without reducing the number of storable files. The advantage is obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a digital camera according to a first embodiment of the present invention.
FIG. 2 is a conceptual diagram illustrating a data configuration of a correspondence table according to the first embodiment.
FIG. 3 is a flowchart for explaining an image data saving operation of the digital camera according to the first embodiment.
FIG. 4 is a conceptual diagram illustrating an image compression operation of the digital camera according to the first embodiment.
FIG. 5 is a conceptual diagram showing a data configuration of a correspondence table in which an encoding method and a change rate of a compressed file size are associated with each other in the second embodiment of the present invention.
FIG. 6 is a flowchart for explaining the operation of the second embodiment.
FIG. 7 is a conceptual diagram showing a data configuration of a correspondence table in which a sub-sampling rate and a change rate of a compressed file size are associated with each other in a third embodiment of the present invention.
FIG. 8 is a flowchart for explaining the operation of the third embodiment.
FIG. 9 is a conceptual diagram showing a data configuration of a correspondence table in which an image size and a change rate of a compressed file size are associated with each other in a fourth embodiment of the present invention.
FIG. 10 is a flowchart for explaining the operation of the fourth embodiment.
FIG. 11 is a conceptual diagram showing a data configuration of a correspondence table in which a file format is associated with a change rate of a compressed file size in a fifth embodiment of the present invention.
FIG. 12 is a flowchart for explaining the operation of the fifth embodiment.
FIG. 13 is a conceptual diagram showing a data configuration of a correspondence table in which additional information and a change rate of a compressed file size are associated with each other in the sixth embodiment of the present invention.
FIG. 14 is a flowchart illustrating the operation of the sixth embodiment.
[Explanation of symbols]
1 lens
2 CCD
3 Timing generator
4 Vertical driver
5 Sample hold circuit
6 A / D converter
7 Color process circuit
8 DMA controller
9 DRAM interface
10 DRAM
11 CPU (size detection means, occupation size detection means, compression parameter determination means, storage control means, file resizing means, file format conversion means)
12 VRAM controller
13 VRAM
14 Digital Video Encoder
15 Display device
16 Operation unit
17 JPEG processing unit (compression means)
18 Flash memory (recording medium)
19 Network connection I / F
20 Program ROM

Claims (15)

In a file storage device for compressing and storing a file on a recording medium having a predetermined minimum recording unit,
Compression means for compressing the file with predetermined compression parameters;
Size detection means for detecting the size of the file compressed by the compression means,
Occupation size detection means for detecting an occupation size when the file compressed by the compression means is stored in the recording medium,
A correction that minimizes an unused area in a minimum recording unit on the recording medium based on the size of the compressed file detected by the size detecting unit and the occupied size of the compressed file detected by the occupied size detecting unit. Compression parameter determining means for determining a compression parameter;
A file storage device, comprising: a storage control unit that recompresses the file by the compression unit based on the corrected compression parameter determined by the compression parameter determination unit and stores the file in a recording medium. The file storage device according to claim 1, wherein the compression parameter is a compression ratio. The file storage device according to claim 1, wherein the compression parameter is an encoding method. The file storage device according to claim 1, wherein the compression parameter is a sampling rate. The compression parameter and the correction compression parameter are the size of the file,
A file resizing means for resizing the file,
The storage control unit resizes the file based on the corrected compression parameter by the file resizing unit prior to compression of the file by the compression unit, and then recompresses the file resized by the compression unit to record on the recording medium. The file storage device according to claim 1, wherein the file is stored in a file. The compression parameter and the correction compression parameter are a file format of the file,
Comprising a file format conversion means for converting the file format of the file,
Prior to the compression of the file by the compression unit, the storage control unit converts the file format of the file based on the corrected compression parameter by the file format conversion unit, and then converts the file format by the compression unit. 2. The file storage device according to claim 1, wherein the file is recompressed and stored in a recording medium. The compression parameter and the correction compression parameter are additional information to be added to the file,
2. The file storage device according to claim 1, wherein the storage control unit re-compresses the data with the additional information based on the corrected compression parameter and stores the re-compressed data on a recording medium. A file saving method for compressing and saving a file on a recording medium having a predetermined minimum recording unit,
Based on the size of the compressed file and the occupied size when the compressed file is stored on the recording medium, the unused area in the minimum recording unit on the recording medium is minimized based on the compression of the file with predetermined compression parameters. A file storage method, comprising: determining a corrected compression parameter to be obtained; re-compressing the file based on the corrected compression parameter; The method according to claim 7, wherein the compression parameter is a compression ratio. The method according to claim 7, wherein the compression parameter is an encoding method. The method according to claim 7, wherein the compression parameter is a sampling rate. The compression parameter and the correction compression parameter are the size of the file,
8. The file storage method according to claim 7, wherein the file is resized based on the corrected compression parameter before the file is compressed, and then the resized file is recompressed and stored on a recording medium. The compression parameter and the correction compression parameter are a file format of the file,
8. The method according to claim 7, wherein, prior to the compression of the file, the file format of the file is converted based on the corrected compression parameter, and then the converted file is recompressed and stored on a recording medium. How to save files. The compression parameter and the correction compression parameter are additional information to be added to the file,
8. The file storage method according to claim 7, wherein the file is recompressed and stored in a recording medium with the additional information based on the corrected compression parameter added. In a file storage program for compressing and storing a file on a recording medium having a predetermined minimum recording unit,
Compressing the file with predetermined compression parameters;
Based on the size of the compressed file and the occupied size when the compressed file is stored on the recording medium, a correction compression parameter that minimizes an unused area in a minimum recording unit on the recording medium Determining
Recompressing the file based on the corrected compression parameter and saving the file on a recording medium.

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