JPH09163293A - Digital still camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evade making picked-up image writing impossible due to the block destruction of a flash memory by permitting the whole data in a memory to be read-only in the case where all the spare blocks are used up. SOLUTION: A flash memory controller 20 connects a flash memory card to a main microcomputer 8. When the block in the memory is destroyed at the time of written picture data in the flash memory, picture data written in the defective block is read from a frame memory 9 again and rewritten in another spare block in the flash memory. In the case where all the spare blocks are used up after executing such rewriting, the file attribute of a file allocation table is changed so as to permit the whole flash memory to be read-only. Then, writing after that is prohibited in the main microcomputer 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital still camera.

[0002]

2. Description of the Related Art A flash EEPROM (hereinafter simply referred to as a flash memory) may be used as a recording medium of a digital still camera.

This flash memory is an EEPROM in which writing can be performed bit by bit and erasing can be performed in all bits or in block units. This flash memory is used as a PC card or is used as a flash memory alone.

The data format of the flash memory is divided into units called blocks, and a spare alternative area called a spare block is provided.
When a block used for recording data (hereinafter referred to as a data block) has a defect, the defective block may be prohibited and a spare block may be used.

A flash memory used as a recording medium of a digital still camera is of a PC card (PCMCIA card) type. Since this PC card is a general-purpose type used in various computers, various binary files and text files may be stored in addition to the image files reproducible by the digital still camera.

When a recording medium in which various kinds of files are mixed is mounted on a digital still camera, the file name, extension, etc. are shown on the display unit, and the file to be reproduced is selected by the user. I was trying to make it. For such a technique, see Japanese Patent Laid-Open No. 12159/1990.
No. 3, for example.

Further, the PC card is provided with two dedicated signal lines for detecting card insertion / removal, and card insertion / removal is detected by the conduction of the signal pin on the digital still camera side corresponding to the signal line. It was

[0008]

[Problems to be solved by the invention]

<First problem> For example, if the data block is destroyed during writing of imaging data after the spare block is used up and the data block remains for one frame image, the imaging data A situation occurs where writing is not possible. Therefore, one frame of image data is wasted.

Further, the flash memory has a characteristic that its performance gradually deteriorates due to the number of times of formatting and the number of times of formatting, and it is expected that the number of defective blocks will increase. In consideration of such characteristics, in order to avoid a situation where the spare blocks are used up and data cannot be written, when the ratio of the spare blocks generated by each format is constant, the ratio of the spare block area is set from the beginning. You have to take a lot. According to such a format, the usage efficiency of the flash memory deteriorates.

Further, in the case where the image storage memory is of a camera built-in type, if the spare block is used up, the camera itself must be replaced. Further, if the data area for accumulating the image pickup data is reduced by increasing the spare block area and prohibiting the use of the defective block, the total number of frames that can be photographed is reduced. Therefore, a situation may occur in which the last one, which should normally be photographable, cannot be actually recorded.

When a defective block is generated, it takes a long time to write if an alternative empty block (spare block) is searched for at the time of shooting. <Second Problem> When a recording medium in which various types of files are mixed is attached to the camera, it is troublesome for the user to select each file.

Further, if the user determines whether or not the file can be displayed after the file is designated by the user, it takes a long time to display the image file.

<Third Problem> Further, by providing a mechanical terminal and a mechanical detection mechanism exclusively for detecting the recording medium, the apparatus becomes complicated and the cost increases.

<Fourth Problem> Further, the amount of image data obtained by photographing is not constant. That is, the size of the compressed image data generated by compression changes depending on the frequency component of the captured image. Therefore, there is a problem that it is difficult to predict the remaining number of shootable images.

<Fifth Problem> Further, in the conventional digital still camera, the data generated by the compression processing is converted into P
When recording on a recording medium such as a C card, in order to absorb the speed difference between the compression processing and the recording processing, temporary data is held in a buffer large enough to accommodate one compressed image data, and then, It was recording.

According to the above technique, the higher the image quality,
Since the number of vertical and horizontal dots and the number of bits for gradation expression are large, the data becomes large. Therefore, the capacity of the buffer memory that is temporarily stored after compression but immediately before recording must be increased.

Further, since compression or expansion processing is performed for one image data as a whole, a wasteful waiting time occurs in the other portions in the time required for each processing. Therefore, it has been desired to minimize the size of the buffer memory and the processing time required for compressing and expanding the image.

<Sixth Problem> In a digital still camera, it is convenient to reduce the contents of a plurality of compressed image data recorded on a recording medium and display them as thumbnail images on a single screen (index). .

However, if the device has a high processing capacity such as a personal computer, it is possible to generate the data for index display from the compressed image data. That is, when a CD-ROM is used as a recording medium, image data stored as compressed data is read out by the computer and generated to generate a thumbnail image. This can be realized by the processing capability of the CPU and graphic circuit installed in the computer, and it is almost impossible to do the same in a digital still camera.

Therefore, realization of a digital still camera capable of displaying thumbnail images of a plurality of compressed image data recorded on a recording medium in an index in a short time has been awaited.

As described above, there are many problems to be solved in the digital still camera. Therefore, a first object of the present invention is to realize a digital still camera capable of avoiding the inability to write a captured image due to block destruction of a flash memory.

A second object of the present invention is that the user does not need to select files one by one even when a recording medium in which various types of files are mixed is attached to the camera, and It is an object of the present invention to realize a digital still camera that can shorten the time until an image file is displayed without having to determine whether the file can be displayed after the file is designated.

A third object of the present invention is to realize a digital still camera which does not need to be provided with a mechanical terminal or a mechanical detecting mechanism dedicated to detecting a recording medium.

A fourth object of the present invention is to realize a digital still camera capable of predicting the remaining number of photographic images for photographic data whose image data amount is not constant.

A fifth object of the present invention is to minimize the size of the buffer memory and the processing time required for recording / reproducing with compression / expansion of an image. Realization of a new digital still camera.

A sixth object of the present invention is to realize a digital still camera capable of displaying thumbnail images of a plurality of compressed image data recorded on a recording medium as an index in a short time. .

[0027]

In order to solve the above-mentioned first problem, the present invention proposes the following digital still cameras (1) to (9).

(1) In a digital still camera having means for converting a captured optical image into a digital signal and means for recording the image data converted into the digital signal in a memory inside the camera or a memory inside a recording medium. The memory is divided into blocks each having a predetermined capacity, a data block for data recording and a spare spare block are provided, and when a defective block occurs in the memory, the defective block is disabled. A digital still camera, wherein a spare block is used, and when the spare block is used up, all data in the memory is read-only.

(2) The digital still camera according to the above (1), further comprising means for notifying a user that the memory is read-only when the memory is read-only. camera.

That is, after the spare block is used up, the memory is set to read-only, and the user of the digital still camera is notified of that fact. In this way, even if the spare block is used up, it is read-only, and by notifying it to the user, the user can be prompted to replace or format the recording medium, and block destruction occurs during writing, making writing impossible. You can prevent the situation.

(3) In the digital still camera, when the preset number of spare blocks is used up, the number of spare blocks in the memory is increased, and the number of spare blocks in the memory is increased. Still camera.

(4) In the digital still camera, the allocation to spare blocks in the memory is increased at the time of formatting the memory.

(5) In the digital still camera described above, the user is informed that the allocation to the spare block in the memory has been increased, and the digital still camera described in (1) above.

(6) In the digital still camera described above, the defective block is prohibited from use and the user is informed that the number of valid blocks has decreased.

(7) In the digital still camera, if a preset number of spare blocks are used up and a defect occurs during data writing, an unrecorded block is searched for and recorded in the unrecorded block. The digital still camera according to the above (1), characterized in that

(8) In the digital still camera, the physical address of an unrecorded block is acquired in advance before writing, and if a defect occurs during the writing of data, recording is re-performed in the acquired unrecorded block. The digital still camera according to (1) above.

(9) In the digital still camera, when the physical address of an unrecorded block is acquired in advance before writing after a spare block of a preset allocation number has been used up and a defect occurs during data writing. In the digital still camera described in (1) above, recording is redone in the acquired unrecorded block.

As described above, the spare block area is set small at first, the spare block is used up, and the spare block area is increased at the time of formatting, whereby the memory can be effectively utilized.

Also, when formatting is executed after the spare blocks have been used up, the allocation of spare blocks is increased, and the user of the camera is notified that the data area has been reduced, so that the user can use the spare blocks. It is possible to know that the area has decreased, and it is possible to recognize the decrease in the total number of shootable images. Therefore, by setting the flash memory as read-only and performing various displays, it becomes possible to prevent erroneous operations and inappropriate operations.

Even if the data area decreases due to the increase of the spare block area or the prohibition of use of the destroyed block, the photographer can know the decrease of the memory amount by displaying the number of shootable images. .

Further, even if a defective block occurs after the spare block has been used up, by writing the data to be written in the defective block to another empty block, the replacement of the card and the repair of the camera can be performed even after the spare block is exhausted. No longer needed.

Further, when a defective block occurs during writing, when rewriting data to another empty block, searching for an empty block in advance before writing shortens the error processing time at the time of writing.

In order to solve the above-mentioned second problem, the present invention proposes the following digital still cameras (10) to (14). (10) Means for converting a photographed optical image into a digital signal, means for recording the image data converted into the digital signal in a memory in a recording medium, and display for displaying the recorded image data in a camera. In a digital still camera having a device or a means for outputting and displaying the data externally, it is checked whether the file data recorded in the recording medium when the recording medium is attached to the camera can be displayed by the digital still camera. A digital still camera characterized in that

That is, when a recording medium in which various types of files are mixed is attached to the camera, it is checked when the recording medium is attached whether or not the file can be displayed by the camera.
Record only visible files in the table.

(11) The digital still camera described in (10) is characterized in that the digital still camera is provided with a table for storing data necessary for selecting a displayable file.

(12) The digital still camera according to (10), characterized in that the digital still camera is provided with a selection means for handling only files capable of displaying images.

(13) The digital still camera according to (10), characterized in that the digital still camera is provided with a table for storing data necessary for selecting a file capable of displaying an image in a photographing order.

(14) The digital still camera is characterized by comprising selection means for using additional data of an image file to select a displayable file (1).
The digital still camera described in 0).

As described above, the annoyance of the user is reduced by automatically determining whether or not the image can be displayed by the camera by using the additional data of the image file. Therefore, even when a recording medium in which various types of files are mixed is attached to the camera, the user does not need to select the files one by one.

Further, it is not necessary to determine whether or not the file can be displayed after the file is designated, and the time until the image file is displayed can be shortened.
In order to solve the above-mentioned third problem, the present invention proposes a digital still camera as described in (15) below.

(15) In the digital still camera, the attachment / detachment of a recording medium is detected using an unused signal line instead of using a dedicated signal line.

By doing so, the existing signal line of the recording medium can be used also as the signal for detecting attachment / detachment, and the structure can be simplified. That is, since no special signal line is used for detecting the mounting of the recording medium, the cost is reduced.

In order to solve the above-mentioned fourth problem, the present invention proposes the following digital still cameras (16) to (17). (16) In the digital still camera having a data storage device in a recording medium or a built-in data storage device, if the data amount of image data is not constant,
A digital still camera, characterized in that when calculating the number of remaining shootable frames, the amount of data of one image is calculated assuming a certain maximum value.

(17) In the digital still camera, when the recordable capacity in the data storage device becomes smaller than the data amount of the image which is assumed to be the certain maximum value, the image data is not recorded. (16) The digital still camera as described above.

In this way, by setting a certain maximum value for the size of one image data and calculating the remaining number of shootable images, it is possible to make an almost accurate prediction of the remaining number of shootable images. Become. That is, the displayed remaining number of shootable frames is always ensured, so that the user is not confused during shooting.

In order to solve the above-mentioned fifth problem, the present invention proposes the following digital still cameras (18) to (21). (18) A conversion means for converting the captured optical image into a digital image signal, a compression means for compressing the digital image signal to generate compressed image data, and a recording means for recording the compressed image data on a recording medium, The recording means includes a buffer memory having a plurality of areas each having a capacity corresponding to a recording / reproducing unit of the recording medium. The plurality of areas are alternately used to perform recording from the buffer memory to the recording medium and compression. A digital still camera characterized in that the compressed image data generated by the means is recorded in a buffer memory.

(19) Conversion means for converting the photographed optical image into a digital image signal, compression means for compressing the digital image signal to generate compressed image data, and recording means for recording the compressed image data on a recording medium. The recording means comprises a buffer memory having a plurality of areas each having a capacity corresponding to a recording / reproducing unit of the recording medium, and the time required for generating the compressed image data by the compression means or the recording from the buffer memory Utilizing the time required for recording on the medium, a plurality of areas of the buffer memory are alternately used to record from one area of the buffer memory onto the recording medium and to store the compressed image data generated by the compression means in the buffer memory. A digital still camera characterized by performing recording on the other area.

(20) Recording means for converting the photographed optical image into a digital image signal, compressing the digital image signal to generate compressed image data, and recording the compressed image data on a recording medium, The recording medium is provided with a reading unit for reading the compressed image data recorded on the recording medium, and a decompressing unit for decompressing the compressed image data to generate a digital image signal. Is provided with a buffer memory having a plurality of areas having a capacity corresponding to, and the plurality of areas are alternately used to perform reading from the recording medium to the buffer memory and reading from the buffer memory to the expanding means. Digital still camera.

(21) Recording means for converting the photographed optical image into a digital image signal, compressing the digital image signal to generate compressed image data, and recording the compressed image data on a recording medium, The recording medium is provided with a reading unit for reading the compressed image data recorded on the recording medium, and a decompressing unit for decompressing the compressed image data to generate a digital image signal. A buffer memory having a plurality of areas having a capacity equivalent to the above, and by utilizing the time required for reading from the recording medium to the buffer memory or the time required for the expansion processing by the expansion means, the plurality of areas of the buffer memory are alternately arranged. Read from the recording medium to one area of the buffer memory and from the other area of the buffer memory to the decompression means. Digital still camera and performing the out look.

As described above, the buffer memory having the plurality of areas having the capacity corresponding to the recording / reproducing unit of the recording medium is provided, and the plurality of areas of the buffer memory are stored by utilizing the time required for each processing. By using them alternately, it is possible to realize a digital still camera that can minimize the size of the buffer memory and the processing time required for recording / reproduction accompanied by image compression / expansion.

In order to solve the above-mentioned sixth problem, the present invention proposes the following digital still cameras (22) to (25). (22) Conversion means for converting the captured optical image into a digital image signal, compression means for compressing the digital image signal to generate compressed image data, and recording / reproducing means for recording and reproducing the compressed image data on a recording medium. A digital still camera comprising: a decompressing unit that decompresses the compressed image data recorded on a recording medium; and an output unit that outputs the decompressed image data as a video signal. A digital still camera characterized in that a digital image signal is subjected to DCT conversion and a DC component thereof is aggregated to generate a thumbnail image.

(23) It is provided with a control means for determining whether the compressed image data recorded on the recording medium is a field image or a frame image, and generating a thumbnail image in which the thumbnail image recorded together with the field image is interpolated line by line. (22) The digital still camera as described above.

(24) It is characterized by comprising a control means for reading a plurality of thumbnail data recorded together with a plurality of compressed image data on a recording medium and generating an image in which a plurality of thumbnail images are arranged on one screen ( 22) A digital still camera as described above.

(25) When thumbnail-in-picture different from the image being reproduced is displayed as a child screen in picture-in-picture mode, either the frame advancing or the frame rewinding operation for the child screen is not performed within a certain time. The digital still camera according to (22), further comprising control means for reading out compressed image data corresponding to the thumbnail image of the small screen and expanding and reproducing the compressed image data.

As described in (22) to (25) above, the thumbnail images of a plurality of compressed image data recorded on the recording medium are displayed as indexes by having thumbnail images in the data file. It will be possible. Also, the thumbnail image can be used to display a small screen.

[0066]

1 shows an embodiment of a digital still camera suitable for carrying out the present invention. First, each operation will be described.

<Embodiment for Achieving the First Object> FIG. 1 is a functional block diagram showing an overall schematic configuration of a digital still camera according to the first embodiment of the present invention.

In the digital still camera shown in FIG. 1, an optical image obtained through an optical system including a lens 1, an iris diaphragm 2 and the like is formed on a light receiving surface of an image pickup device 3 such as a CCD. . At this time, the lens 1 and the iris diaphragm 2 are respectively provided with the focus drive circuit 16
And the diaphragm drive circuit 15.

Here, the image pickup device 3 photoelectrically converts the optical image formed on the light receiving surface into a charge amount, and outputs an analog image signal in response to a transfer pulse from the CCD drive circuit 19.
The output analog image signal is supplied to the preprocessing circuit 4
In, noise is reduced by CDS (correlated double sampling) processing, gain is adjusted by AGC, and secondary processing for expanding the dynamic range is performed.

After being converted into a digital image signal by the A / D converter 5, the signal processing circuit 6 performs brightness processing and color processing to obtain a digital video signal (for example, a brightness signal (Y) and a color difference signal ( Cr, Cb)) and output to the memory controller 7.

On the other hand, the signal processing circuit 6 also has a built-in D / A converter, and a colorized video signal input from the A / D converter 5 side and a reverse input from the memory controller 7. It is also possible to output the image data as an analog video signal.

These functions are switched by exchanging data with the main microcomputer 8, and the exposure information, focus signal, and white balance information of the image pickup device signal can be output to the main microcomputer 8 as necessary.

The main microcomputer 8 is mainly used for photographing,
It controls the sequence of recording and playback, and also performs compressed playback of captured images and serial port transmission with external devices as necessary. Here, CCITT and ISO are used as image compression.
The JPEG method or the JBIG method, which is standardized by the above, is used.

Then, the memory controller 7 accumulates the digital image data input from the signal processing circuit 6 in the frame memory 9 and, conversely, outputs the image data in the frame memory 9 to the signal processing circuit 6.

The frame memory 9 is an image memory capable of accumulating image data of at least one screen. For example, VRAM, SRAM, DRAM or the like is generally used. Here, a VRAM that can operate independently of the CPU bus is used. doing.

The image storage memory 10 is a memory built in the main body, and stores the image data stored in the frame memory 9 after being subjected to image compression processing or the like by the main microcomputer 8. As the image storage memory 10,
For example, SRAM, DRAM, EEPROM or the like is used, but EEPROM is preferable in consideration of storing the image data in the memory.

The PC card controller (PCMCIA controller) 11 is a PC memory card (hereinafter simply referred to as a PC
An external recording medium such as a card) and the main microcomputer 8 are connected to each other, and an image stored in the frame memory 9 is subjected to an image compression process or the like by the main microcomputer 8 and then, via the controller 11. And is recorded in an external storage medium. The external storage PC card connected via the PC card controller 11 is an SRAM.
A card, a DRAM card, an EEPROM card or the like can be used, and a modem card or an ISDN card can be used to directly transfer image data to a remote storage medium via a public line.

The strobe 12 is designed so that the light emission timing can be obtained by the main microcomputer 8 which controls the photographing sequence. The serial port driver 13 performs signal conversion for performing information transmission between the camera body and information between external devices. As the serial transmission means, RS23
There are recommended standards for performing serial communication such as 2C and RS422A, but here, RS232C is used.

The sub-microcomputer 14 controls an operation switch of the camera body and a man-machine interface such as a liquid crystal display, and transmits information to the main microcomputer 8 as necessary. Here, a serial input / output terminal is used for transmitting information to and from the main microcomputer 8. It also has a built-in clock function and controls the auto date.

The diaphragm driving section 15 is composed of, for example, an auto iris, and changes the optical diaphragm value of the diaphragm 2 under the control of the main microcomputer 8. The focus drive unit 16 is composed of, for example, a stepping motor,
The lens position is changed under the control of the main microcomputer 8 so that the optical focus surface of the subject is properly adjusted on the image pickup device 3. The liquid crystal display unit 18 is the sub-microcomputer 1
4 is a display unit that is connected to the display unit 4 and displays various information such as shooting information.

The flash memory controller 20 connects the flash memory card, which is not in the above-mentioned PC card format, and the main microcomputer 8. The image photographed in the frame memory 9 is subjected to image compression processing or the like on the main microcomputer 8. Then, the data is recorded on the external recording medium via the flash memory controller 20.

In the structure shown in FIG. 1, the main microcomputer 8 compresses and expands an image, but a dedicated circuit for compression / expansion may be arranged on the CPU bus.

Next, a series of operations from photographing to memory recording will be described. The operation mode of the camera is set based on various switch information connected to the sub-microcomputer 14, and information for photographing is input to the main microcomputer 8 as serial information. In accordance with this information, the main microcomputer 8 sets the memory controller 7 and the serial port driver 13. Further, the PC card controller section, the flash memory controller, and the serial port driver section are set as necessary.

When the release switch on the sub-microcomputer 14 is pressed halfway (S1on), the sub-microcomputer 14 transmits the information to the main microcomputer 8. When the main microcomputer 8 learns that the S1 signal has become active, the signal processing circuit 6
An image input command is issued to the signal processing circuit 6, and the signal processing circuit 6 operates the image pickup device 3, the preprocessing circuit 4, and the A / D converter 6 to receive a CCD image.

The signal processing circuit 6 performs basic signal processing on the received CCD image data, and then creates focus information from the high frequency component of the brightness data and exposure data from the low frequency component. The main microcomputer 8 reads these data from the signal processing circuit 6 and drives the diaphragm and the focus as necessary, and further performs pre-process AG.
The gain of the C amplifier is controlled to converge until proper exposure and focus are obtained. Depending on the operation mode, the signal processing circuit 6 outputs an analog image signal to output N
Output as a TSC video signal to an external monitor.

After the exposure value and the focus are adjusted to appropriate values, when the signal (S2on) indicating that the release switch is fully pressed is input from the sub-microcomputer 14 to the main microcomputer 8, the main microcomputer 8 causes the memory controller to operate. The fetching instruction is output to 7. Also, if necessary, a light emission signal is output to the strobe 12 at the field timing of the captured image.

When the memory controller 7 receives an image capture command, it detects a synchronization signal from the signal processing circuit 6 and outputs image data in the Y-Cr-Cb format or the like output from the signal processing circuit 6 at a predetermined timing. Captured in the frame memory 9. When the capture of the image is completed in the frame memory 9, the memory controller 7 displays a status indicating that the capture is completed. By reading this status by the main microcomputer 8, the main microcomputer 8 side recognizes that the photographing is completed.

After the photographing is completed, the main microcomputer 8 performs image compression of the imaged data as needed, and is connected to the image storage memory 10, an externally connected PC card or flash memory, or an external serial port. Transfer image data to a personal computer.

When the image data is written to the image storage memory 10 or the flash memory and a block in the memory is destroyed (this destroyed block is referred to as a defective block), the image data written in the defective block is rewritten. Image storage memory 1 read from the frame memory 9
Rewrite to 0 or another spare block in the flash memory. In this case, in which spare block the data originally written in the data block has been written is recorded in the management area. For the defective block, the block number is recorded in the management area, and the fact that writing and reading are prohibited is recorded.

When such a rewriting is executed and the spare block is used up (or when the remaining amount of the spare block is less than a certain amount), further writing is prohibited. One of the following processes (or a combination of the following processes) is executed. -Change the file attribute of the file allocation table (FAT) so that the entire flash memory is read-only. The main microcomputer 8 recognizes that the flash memory is read-only and prohibits subsequent writing. The flash memory controller 20 recognizes that the flash memory is read-only and prohibits subsequent writing. The liquid crystal display unit 18 displays that the flash memory cannot be written and that shooting cannot be performed. When the release switch is pressed, a warning indicating that photography is not possible is displayed on the liquid crystal display unit 18.・ When the release switch is pressed, a warning sound is emitted indicating that shooting is not possible.

As described above, by setting the flash memory as read-only and performing various displays, it becomes possible to prevent erroneous operations and inappropriate operations. That is, even if the spare block is used up, it is read-only, and by notifying the user of it, the user can be prompted to replace or format the recording medium, and block destruction occurs during writing, making it unwritable. Can be prevented.

After the read-only procedure, when the user formats the flash memory, the flash memory controller 20 executes the formatting so as to increase the spare block area of the flash memory.

That is, the fact that the spare block is used up due to the defective block generated immediately before the formatting means that there is a possibility that the defective block may be generated and the spare block may be insufficient in the future use. Therefore, at the time of formatting, formatting is performed so as to increase the spare block area (spare block number).

This state is shown in FIG. Here, FIG.
(A) shows the state of the block generated by the initial format. For example, the post-format capacity of the entire flash memory is 2 MB, and 512 blocks are generated by using this as a block of 4 kB.
Here, the ratio of the spare block to the total capacity is 2
By performing the initial formatting as%, the data blocks become 490 blocks of A1 to A490, the spare blocks become 10 blocks of B1 to B10, and the rest become blocks of the management area (hereinafter referred to as management blocks).

In this management block, the spare block to which the data to be originally written in the data block was written, the block number of the defective block, and the like are recorded.

During use in such an initial format state, the spare blocks 10 to 10 as described above are used.
In the format after 100 is used up, FIG.
Increase the number of spare blocks as shown in. Here, the result of formatting the spare block ratio of 2% in the initial format and the spare block ratio of 4% is shown. That is, the data block is reduced to 480 blocks and the spare block is increased to 20 blocks.

In this way, the spare block area is set to a small value at first, the spare block is used up, and then the spare block area is gradually increased at the time of formatting to make the capacity of the normally used area of the flash memory effective. Can be used for.

Further, the ratio of increasing the spare blocks is not limited to the above example, and various changes can be made. For example, it is possible to increase the spare block ratio such as 2% → 4% → 6%. Further, finally, by allocating one sheet of the most precise image (for example, 128 kbytes) to the spare block, even if a bad block suddenly occurs during use, it is possible to record the captured image. It can be avoided. Such a format is executed by the flash memory controller 20 based on an instruction from the main microcomputer 8.

When such a format is executed, there is a possibility that the total number of shootable images after formatting is less than the total number of shootable images before formatting. Therefore, the capacity of the formatted data block is displayed on the gauge showing the remaining capacity of the image storage memory 10 or the flash memory of the liquid crystal display unit 18. That is, a gauge having the maximum value (100%) of the capacity of the data block obtained by the initial format is provided, and the gauge shows the capacity of the data block after each format. By performing such a display, since the allocation of spare blocks is increasing, the gauge does not reach 100% immediately after formatting.

As a result, the user can visually recognize that the usable area has decreased, and can recognize the decrease in the total number of photographable images. Therefore, by setting the flash memory as read-only and performing various displays, it becomes possible to prevent erroneous operations and inappropriate operations.

Further, in the above case, when the spare block is used up during the writing, the main microcomputer 8 checks the management area of the flash memory, finds an unrecorded block in the data block, and writes it in this unrecorded data block. It is also possible to re-record. By doing so, it is possible to prevent a state in which block destruction occurs during writing and writing becomes impossible.

If an unrecorded data block is searched in advance before writing and the above-mentioned processing is performed, the error processing time at the time of writing can be shortened. The use of the unrecorded data block may be performed before the spare block is used up.

In the reproduction display operation, the main microcomputer 8 reads image data from the image storage memory 10, an externally connected PC card, or a personal computer connected to an external serial port, and if necessary, reads the image data. The image is expanded by using the frame memory 9
Write to. After that, when a command for displaying an image is issued to the signal processing circuit 6 and the memory controller 7, the memory controller 7 reads the image data from the frame memory 9, and the image processing is performed to the NTSC output terminal via the signal processing circuit 6. Output an analog signal.

In this way, the functions of the camera for photographing, recording, reproducing, displaying and transmitting are achieved. <Embodiment for Achieving Second Object> FIG. 3 is a functional block diagram showing an overall schematic configuration of a digital still camera according to an embodiment for achieving the second object of the present invention.

In the digital still camera shown in FIG. 3, an optical image obtained through an optical system including a lens 1, an iris diaphragm 2 and the like is formed on a light receiving surface of an image pickup device 3 such as a CCD. . At this time, the lens 1 and the iris diaphragm 2 are respectively provided with the focus drive circuit 16
And the diaphragm drive circuit 15.

Here, the image pickup device 3 photoelectrically converts the optical image formed on the light receiving surface into a charge amount, and outputs an analog image signal by a transfer pulse from the CCD drive circuit 19.
The output analog image signal is supplied to the preprocessing circuit 4
In, noise is reduced by CDS (correlated double sampling) processing, gain is adjusted by AGC, and secondary processing for expanding the dynamic range is performed.

After being converted into a digital image signal by the A / D converter 5, the signal processing circuit 6 performs brightness processing and color processing on the digital video signal (for example, the brightness signal (Y) and the color difference signal ( Cr, Cb)) and output to the memory controller 7.

On the other hand, the signal processing circuit 6 also has a built-in D / A converter, and a colorized video signal input from the A / D converter 5 side and an inverse input from the memory controller 7. It is also possible to output the image data as an analog video signal.

These functions are switched by exchanging data with the main microcomputer 8, and the exposure information, focus signal and white balance information of the image pickup device signal can be output to the main microcomputer 8 as necessary.

This main microcomputer 8 is mainly used for photographing,
It controls the sequence of recording and playback, and also performs compressed playback of captured images and serial port transmission with external devices as necessary. Here, CCITT and ISO are used as image compression.
The JPEG method or the JBIG method, which is standardized by the above, is used.

Then, in the memory controller 7, the digital image data input from the signal processing circuit 6 is accumulated in the frame memory 9, and conversely, the image data in the frame memory 9 is output to the signal processing circuit 6.

The frame memory 9 is an image memory capable of accumulating image data of at least one screen. For example, VRAM, SRAM, DRAM or the like is generally used. Here, a VRAM that can operate independently of the CPU bus is used. doing.

The image storage memory 10 is a memory built in the main body and stores the image data stored in the frame memory 9 after being subjected to image compression processing by the main microcomputer 8. As the image storage memory 10,
For example, SRAM, DRAM, EEPROM or the like is used, but EEPROM is preferable in consideration of storing the image data in the memory.

The PC card controller (PCMCIA controller) 11 is a PC memory card (hereinafter simply referred to as PC
An external recording medium such as a card) and the main microcomputer 8 are connected to each other, and an image stored in the frame memory 9 is subjected to an image compression process or the like by the main microcomputer 8 and then, via the controller 11. And is recorded in an external storage medium. The external storage PC card connected via the PC card controller 11 is an SRAM.
A card, a DRAM card, an EEPROM card or the like can be used, and a modem card or an ISDN card can be used to directly transfer image data to a remote storage medium via a public line.

The strobe 12 is designed so that the light emission timing can be obtained by the main microcomputer 8 which controls the photographing sequence. The serial port driver 13 performs signal conversion for performing information transmission between the camera body and information between external devices. As the serial transmission means, RS23
There are recommended standards for performing serial communication such as 2C and RS422A, but here, RS232C is used.

The sub-microcomputer 14 controls man-machine interfaces such as operation switches of the camera body and a liquid crystal display, and transmits information to the main microcomputer 8 as necessary. Here, a serial input / output terminal is used for transmitting information to and from the main microcomputer 8. It also has a built-in clock function and controls the auto date.
The insertion / extraction state of the flash memory is also detected by referring to the card detection signal line.

The diaphragm drive unit 15 is composed of, for example, an auto iris, and changes the optical diaphragm value of the diaphragm 2 under the control of the main microcomputer 8. The focus drive unit 16 is composed of, for example, a stepping motor,
The lens position is changed under the control of the main microcomputer 8 so that the optical focus surface of the subject is properly adjusted on the image pickup device 3. The liquid crystal display unit 18 is the sub-microcomputer 1
4 is a display unit that is connected to the display unit 4 and displays various information such as shooting information.

The flash memory controller 20 connects the flash memory card, which is not in the above-mentioned PC card format, to the main microcomputer 8. The image photographed in the frame memory 9 is subjected to image compression processing on the main microcomputer 8. Then, the data is recorded on the external recording medium via the flash memory controller 20.
The configuration shown in FIG. 3 shows the case where the main microcomputer 8 compresses and decompresses an image.
A dedicated circuit for compression / expansion may be arranged on the bus.

The flash memory used here is connected to the sub-microcomputer 1 by connecting spare signal lines and GND lines.
The insertion / removal can be detected from the 4 side. The card detection signal line connected between the card connector and the sub-microcomputer is pulled up by a resistor.
When the card is inserted, the signal drops to GND, and the sub-microcomputer 14 can know that the card is inserted or removed.

Now, a series of basic operations from photographing to memory recording will be described. The operation mode of the camera is set from various switch information connected to the sub-microcomputer 14, and the information for photographing is output to the main microcomputer 8 as serial information. Depending on this information, the main microcomputer 8
Sets the memory controller 7, the signal processing circuit 6, the preprocessing circuit 4, and if necessary, the PC card controller 11, the flash memory controller 20, and the serial port driver 13.

When the release switch on the sub-microcomputer 14 is pressed halfway and the S1 signal is turned on, the sub-microcomputer 14 section sends the information to the main microcomputer 8. When the main microcomputer 8 learns that the S1 signal has become active, it issues an image input command to the signal processing circuit 6,
Operates the image sensor 3, the pre-process circuit 4, and the A / D converter 5 to receive a captured image. The signal processing circuit 6 performs basic signal processing on the received captured image data, and then creates focus information from the high frequency component of the brightness data and exposure data from the low frequency component.

The main microcomputer 8 reads these data from the signal processing circuit 6 and performs aperture drive and focus drive as required, and further performs gain control of preprocess AGC amplification until proper exposure and focus are obtained. Make you converge. Also, depending on the operation mode, the signal processing circuit 6 outputs an analog image signal and outputs it as an NTSC signal to an external monitor.

After the exposure value and focus converge to appropriate values,
When the release switch is fully pressed by the sub-microcomputer 14 to the main microcomputer 8 to turn on the S2 signal, the main microcomputer 8 outputs a fetch command to the memory controller 7. Further, if necessary, a light emission signal is also output to the strobe unit at the field timing of the captured image. When the memory controller 7 receives an image capture command,
The synchronization signal from the signal processing circuit 6 is detected, and the image data in the YCrCb format or the like output from the signal processing circuit 6 is taken into the frame memory at a predetermined timing. When the capture of the image is completed in the frame memory unit, the memory controller 7 displays a status indicating that the capture is completed, and the main microcomputer 8 reads this to know that the photographing is completed on the main microcomputer side.

After the photographing is finished, the main microcomputer 8 compresses the image as necessary, and stores it in the image storage memory.
Image data is transferred to an externally connected PC card or flash memory, or to a personal computer connected to an external serial port. The size of the compressed image data generated by compression here changes depending on the frequency component of the captured image.

In the reproduction display operation, the main microcomputer 8
Image data is read from the image storage memory 10, an externally connected PC card or flash memory, or a personal computer connected to an external serial port, the image is decompressed as necessary, and written in the frame memory. .

Since it is possible that the PC card or flash memory contains image data that is not image data or that cannot be reproduced by this system, it is checked whether each file can be reproduced when the card is inserted and recorded in the table. . This operation will be described later.

After that, when a command for displaying an image is issued to the signal processing circuit 6 and the memory controller 7, the memory controller 7 reads the image data from the frame memory unit and outputs it to the NTSC output terminal via the signal processing circuit 6. The analog signal of the image is output.

In this way, the functions of the camera for photographing, recording, reproducing, displaying and transmitting are achieved. Here, the characteristic portion that solves the above-described second problem will be described. When a recording medium (flash memory) in which various types of files are mixed is attached to the camera, it is troublesome for the user to select each file. Further, if the camera determines whether or not the file can be displayed after the file is designated by the user, it takes a long time to display the image file.

Therefore, when the flash memory is attached to the digital still camera, it is checked whether the file data recorded in the flash memory can be displayed by the digital still camera. In other words, when a flash memory containing various types of files is installed in a digital still camera,
Check whether the file can be displayed and record only the file that can be displayed in the table. FIG. 4A shows a directory on the flash memory side, and FIG.
Indicates a directory of displayable files recorded in the table of the digital still camera.

In this case, the main microcomputer 8 determines whether or not display is possible by the following items. -The file name extension stored in the directory entry or the like determines whether the image file is a displayable image file or a non-displayable file in another format. -It is judged by checking whether a symbol or the like indicating a displayable image file is included at a predetermined position in the file. For example, in the case of a JPEG format file, it is checked whether it is [SOI] at the beginning of valid data in the file. -If there is a limit to the image size of a reproducible image file, determine whether the data is within the limit. For example, the determination is made by reading the data of the number of pixels and the number of lines of the image from the header information (additional information) existing in the file.

Then, as a result of the above judgment,
When a displayable image file is detected, the contents of the directory entry of the displayable image file are held in the table (FIG. 4B) in the main memory of the main microcomputer 8. Further, in this case, it is preferable to arrange the files in order of creation date and time.

The above judgment and table holding are executed when the flash memory is mounted on the digital still camera. By doing so, it becomes possible to instantly display only the file names that can be displayed on the liquid crystal display unit 18 even when the user gives an instruction for actual reproduction. Further, even if there is no reproduction instruction, the reproducible file name can be displayed when the above judgment and table holding are completed.

Therefore, the user can select the file to be reproduced without waiting time. <Embodiment for Achieving Third Object> Here, a characteristic portion for solving the third problem described above will be described. As described above, the provision of the mechanical terminals and the mechanical detection mechanism dedicated to the detection of the recording medium complicates the apparatus and raises the cost.

Therefore, in the card type flash memory, if any of the following signal lines is present, at least one of them is the GN of the digital still camera.
The slot on the digital still camera side is wired so that it is connected to D and at least one other is connected to the pulled-up card detection signal line. In the card-type flash memory, the signal lines corresponding to the above wirings are wired so as to be electrically connected to each other. -Multiple GND signal lines-Multiple unused (spare) signal lines-One or more unused (spare) signal lines and one or more GND
In this way, by using one of the GND signal line or the unused signal line as the GND and the other as the detection signal line,
When the card type flash memory is inserted into the slot of the digital still camera, the sub-microcomputer 14
The potential of the detection signal line connected to is changed to low level. Further, the potential of the detection signal line changes to high level when the flash memory is removed.

This change in potential allows the sub-microcomputer 14 to detect the insertion / extraction of the flash memory. Then, in such detection of insertion / removal, a dedicated mechanism, a dedicated terminal, etc. are not required.

In FIG. 5, there are three mutually connected GND signal lines in the flash memory card 24, and one of them is the card detection signal line 22.
As a result, it is pulled up by the pull-up resistor 23 and connected to the detection port of the main microcomputer 8.

That is, the existing signal line of the recording medium can be used as the signal for the attachment / detachment detection, and the structure can be simplified. That is, since no special signal line is used for detecting the mounting of the recording medium, the cost is reduced.

<Embodiment for Achieving Fourth Object> Here, a characteristic portion for solving the above-mentioned fourth problem will be described. As described above, the amount of image data obtained by shooting is not constant. That is, although the image data obtained by the image sensor is stored as compressed data, the size of the compressed image data generated by compression changes because the compression rate changes depending on the frequency component of the captured image. . For this reason, it is difficult to predict the remaining number of shootable images.

Therefore, in this embodiment, the main microcomputer 8 controls the following operations. When the data amount of image data is not constant, the data amount of one image is assumed to be a certain maximum value when calculating the number of remaining shootable frames. When the recordable capacity (remaining capacity) in the data storage device becomes smaller than the data amount of the image which is assumed to be the certain maximum value, the image data is not recorded (captured).

FIG. 6 is an explanatory view schematically showing the internal condition of the flash memory in a state where up to 8 frames have been photographed. Here, based on the above-described method, the main microcomputer 8 determines that it is possible to shoot another three frames in the unrecorded area.

FIG. 7 is an explanatory view schematically showing the internal condition of the flash memory which has photographed up to 11 frames. Here, since the unrecorded area is less than the maximum capacity of one frame, the main microcomputer 8 determines to stop shooting.

As described above, by setting a certain maximum value for the size of one image data and calculating the remaining number of shootable images, it is possible to make an almost accurate prediction of the remaining number of shootable images. Become. In this case, even if an error occurs, it is possible to avoid a situation in which recording cannot be performed because the error is in the direction in which the remaining capacity has a margin. That is, the displayed remaining number of frames that can be photographed is always ensured, so that the user is not confused during photographing. In addition, even if the shooting is stopped when the remaining capacity is equal to or less than a certain value, it is possible to avoid a situation in which recording cannot be performed.

<Embodiment for Achieving Fifth Objective> FIG. 8 is a functional block diagram showing an overall schematic configuration of a digital still camera according to an embodiment for achieving the fifth objective of the present invention. is there.

In the digital still camera shown in FIG. 8, an optical image obtained through an optical system composed of a lens 1, an iris diaphragm 2 and the like is formed on a light receiving surface of an image pickup device 3 such as a CCD. . At this time, the lens 1 and the iris diaphragm 2 are respectively provided with the focus drive circuit 16
And the diaphragm drive circuit 15.

Here, the image pickup device 3 photoelectrically converts the optical image formed on the light receiving surface into a charge amount, and outputs an analog image signal by the transfer pulse from the CCD drive circuit 19.
The output analog image signal is supplied to the preprocessing circuit 4
In, noise is reduced by CDS (correlated double sampling) processing, gain is adjusted by AGC, and secondary processing for expanding the dynamic range is performed.

After being converted into a digital image signal by the A / D converter 5, the signal processing circuit 6 performs brightness processing and color processing to obtain a digital video signal (for example, a brightness signal (Y) and a color difference signal ( Cr, Cb)) and output to the memory controller 7.

On the other hand, the signal processing circuit 6 also has a built-in D / A converter, and a colorized video signal input from the A / D converter 5 side and an inverse input from the memory controller 7. It is also possible to output the image data as an analog video signal.

These functions are switched by exchanging data with the main microcomputer 8, and the exposure information, focus signal, and white balance information of the image pickup device signal can be output to the main microcomputer 8 if necessary.

The main microcomputer 8 is mainly used for photographing,
It controls the sequence of recording and playback, and also performs compressed playback of captured images and serial port transmission with external devices as necessary. Here, CCITT and ISO are used as image compression.
The JPEG method or the JBIG method, which is standardized by the above, is used.

Then, the memory controller 7 accumulates the digital image data input from the signal processing circuit 6 in the frame memory 9 and, conversely, outputs the image data in the frame memory 9 to the signal processing circuit 6.

The frame memory 9 is an image memory capable of accumulating image data of at least one screen, and for example, VRAM, SRAM, DRAM or the like is generally used. Here, the VRAM capable of operating independently of the CPU bus is used. doing.

A buffer memory 10 'as an image storage memory is a memory built in the main body, and is a frame memory 9'.
The image data stored in the main microcomputer 8 that has been subjected to image compression processing and the like is stored. Examples of the image storage memory 10 include SRAM, DRAM,
Although an EEPROM or the like is used, the EEPROM is preferable in consideration of storing the image data in the memory.
Further, the buffer memory 10 'is divided into a plurality of areas as will be described below, and is configured such that reading and writing can be performed independently of each other.

The PC card controller (PCMCIA controller) 11 is a PC memory card (hereinafter simply referred to as PC
An external recording medium such as a card) and the main microcomputer 8 are connected to each other, and an image stored in the frame memory 9 is subjected to an image compression process or the like by the main microcomputer 8 and then, via the controller 11. And is recorded in an external storage medium. The external storage PC card connected via the PC card controller 11 is an SRAM.
A card, a DRAM card, an EEPROM card or the like can be used, and a modem card or an ISDN card can be used to directly transfer image data to a remote storage medium via a public line.

The strobe 12 is designed so that the light emission timing can be obtained by the main microcomputer 8 which controls the photographing sequence. The serial port driver 13 performs signal conversion for performing information transmission between the camera body and information between external devices. As the serial transmission means, RS23
There are recommended standards for performing serial communication such as 2C and RS422A, but here, RS232C is used.

The sub-microcomputer 14 controls operation switches of the camera body and a man-machine interface such as a liquid crystal display, and transmits information to the main microcomputer 8 as necessary. Here, a serial input / output terminal is used for transmitting information to and from the main microcomputer 8. It also has a built-in clock function and controls the auto date.
The insertion / extraction state of the flash memory is also detected by referring to the card detection signal line.

The diaphragm drive unit 15 is composed of, for example, an auto iris, and changes the optical diaphragm value of the diaphragm 2 under the control of the main microcomputer 8. The focus drive unit 16 is composed of, for example, a stepping motor,
The lens position is changed under the control of the main microcomputer 8 so that the optical focus surface of the subject is properly adjusted on the image pickup device 3. The liquid crystal display unit 18 is the sub-microcomputer 1
4 is a display unit that is connected to the display unit 4 and displays various information such as shooting information.

The flash memory controller 20 connects the flash memory card which is not in the above-mentioned PC card format and the main microcomputer 8, and the image photographed in the frame memory 9 is subjected to image compression processing or the like on the main microcomputer 8. Then, the data is recorded on the external recording medium via the flash memory controller 20.
In the configuration shown in FIG. 8, the main microcomputer 8 compresses and decompresses an image.
A dedicated circuit for compression / expansion may be arranged on the bus.

The flash memory used here is connected to the sub-microcomputer 1 by connecting a spare signal line or GND line.
The insertion / removal can be detected from the 4 side. The card detection signal line connected between the card connector and the sub-microcomputer is pulled up by a resistor.
When the card is inserted, the signal drops to GND, and the sub-microcomputer 14 can know that the card is inserted or removed.

Now, a series of basic operations from photographing to memory recording will be described. The operation mode of the camera is set from various switch information connected to the sub-microcomputer 14, and the information for photographing is output to the main microcomputer 8 as serial information. Depending on this information, the main microcomputer 8
Sets the memory controller 7, the signal processing circuit 6, the preprocessing circuit 4, and if necessary, the PC card controller 11, the flash memory controller 20, and the serial port driver 13.

When the release switch on the sub-microcomputer 14 is half-pressed and the S1 signal is turned on, the sub-microcomputer 14 section transmits the information to the main microcomputer 8. When the main microcomputer 8 learns that the S1 signal has become active, it issues an image input command to the signal processing circuit 6,
Operates the image sensor 3, the pre-process circuit 4, and the A / D converter 5 to receive a captured image. The signal processing circuit 6 performs basic signal processing on the received captured image data, and then creates focus information from the high frequency component of the brightness data and exposure data from the low frequency component.

The main microcomputer 8 reads these data from the signal processing circuit 6 and performs aperture drive and focus drive as required, and further performs gain control of preprocess AGC amplification until proper exposure and focus are obtained. Make you converge. Also, depending on the operation mode, the signal processing circuit 6 outputs an analog image signal and outputs it as an NTSC signal to an external monitor.

After the exposure value and focus converge to appropriate values,
When the release switch is fully pressed by the sub-microcomputer 14 to the main microcomputer 8 to turn on the S2 signal, the main microcomputer 8 outputs a fetch command to the memory controller 7. Further, if necessary, a light emission signal is also output to the strobe unit at the field timing of the captured image. When the memory controller 7 receives an image capture command,
The synchronization signal from the signal processing circuit 6 is detected, and the image data in the YCrCb format or the like output from the signal processing circuit 6 is taken into the frame memory at a predetermined timing. When the capture of the image is completed in the frame memory unit, the memory controller 7 displays a status indicating that the capture is completed, and the main microcomputer 8 reads this to know that the photographing is completed on the main microcomputer side.

After the photographing is finished, the main microcomputer 8 compresses the image as required, and stores it in the image storage memory.
Image data is transferred to an externally connected PC card or flash memory, or to a personal computer connected to an external serial port. The size of the compressed image data generated by compression here changes depending on the frequency component of the captured image.

In the reproduction display operation, the main microcomputer 8
Image data is read from the image storage memory 10, an externally connected PC card or flash memory, or a personal computer connected to an external serial port, the image is decompressed as necessary, and written in the frame memory. .

Since it is possible that the PC card or flash memory contains image data that is not image data or that cannot be reproduced by this system, it is checked whether or not each file can be reproduced when the card is inserted and recorded in the table. . This operation will be described later.

After that, when a command for displaying an image is issued to the signal processing circuit 6 and the memory controller 7, the memory controller 7 reads the image data from the frame memory unit and outputs it to the NTSC output terminal via the signal processing circuit 6. The analog signal of the image is output.

As described above, the basic functions of the camera such as photographing, recording, reproducing, displaying and transmitting are achieved. Here, the characteristic portion that solves the fifth problem described above will be described.

The buffer memory 10 'shown in FIG. 8 does not have the size of one piece of compressed image data as in the prior art, but corresponds to the capacity of the recording / reproducing unit of the recording medium (PC card, flash memory). It has a plurality of regions of capacity. That is, when a general PC card or flash memory is composed of 4 kilobytes per block, it is assumed that the buffer memory 10 'is composed of two 4 kilobyte areas. Here, two buffer memories are secured, and these buffers are called a first buffer / second buffer.

First, the recording operation after photographing will be described with reference to the overall flowchart of FIG. 9, the flowchart of the main part of FIG. 10, and the schematic diagram of FIG. The main microcomputer 8 is a buffer (first buffer /
The second buffer) is designated (S1 in FIG. 9). Here, the description will be continued assuming that the first buffer is designated.

After the photographing is completed, the main microcomputer 8 performs image compression for each MCU (minimum coding unit: minimum unit) (FIG. 9S2).
Compressed data is generated in a buffer memory of about 4 kB secured in the image storage memory (S3 in FIG. 9). For this image compression, for example, processing is performed in the unit of one block of 8 × 8 pixels as the minimum unit.

The state of this compression is shown in detail in FIG. That is, cutout of 8 × 8 pixels (FIG. 10S1),
The pixel is subjected to DCT transform (FIG. 10S2), further quantized (FIG. 10S3), and Huffman coded (FIG. 10S).
Perform 4).

This processing is repeated for each MCU (FIG. 9S).
4) Compressed data for one buffer (4 kB) is generated (S5 in FIG. 9). Next, the compressed data already generated in the first buffer is written in a recording medium such as a PC card. At this time, if the ready / busy signal of the recording medium is busy, compressed data generation processing is performed in the second buffer until it becomes ready (FIG. 9 S6, S7, S8, S9, S10), and the dead time is made effective. Use and minimize the time required for image recording.

When the recording medium side becomes ready, interrupt,
Due to the flag or the like, the compressed data generation process in the second buffer is interrupted, and writing from the data in the first buffer to the PC card is restarted (S11 in FIG. 9).

Thus, all the data in the first buffer is P
When written on a recording medium such as a C card (Fig. 9S1
2), compressed data is generated in the second buffer (FIG. 9).
S8, S9, S10).

When the compressed data is written in the second buffer, the data in the second buffer is written in the recording medium such as a PC card, and the compressed data is generated in the first buffer. Such processing is repeated (S13 in FIG. 9) to compress the entire image.

Further, this situation will be schematically described as shown in FIG. That is, initial state → state 1 → state 2 → state 3 → state 4 → state 5 → state 2 → ...
The first buffer and the second buffer are repeatedly operated to operate alternately.

As described above, the generation of the compressed data and the recording on the recording medium can be efficiently performed by utilizing the mutual waiting time. Next, regarding the reproducing operation, FIG.
2 will be described with reference to the entire flowchart of FIG. 2, the flowchart of the main part of FIG. 13, and the schematic diagram of FIG.

The main microcomputer 8 is a buffer (first buffer / second buffer) for reading compressed data from a recording medium.
Is designated (S1 in FIG. 12). Here, the description will be continued assuming that the first buffer is designated.

Then, the main microcomputer 8 reads the compressed image data from an externally connected recording medium such as a PC card, and secures it in the image storage memory at 4 kB.
The compressed data is stored in a buffer memory of a certain size (Fig. 12
S2).

Next, the data stored in the first buffer is decompressed for each MCU (8 pixels × 8 pixels) (FIG. 12, S3, S4), and the state of this compression is shown in FIG.
The details are shown below. That is, Huffman decoding (FIG. 13S
1), inverse quantization (FIG. 13S2), inverse DCT conversion (FIG. 13S3), and then writing in 8 × 8 pixel units (FIG. 13S4).

When the unexpanded data in the buffer is reduced to about 200 bytes by this image expansion (FIGS. 12S5 and S6), the compressed image data is read from the PC card and stored in the second buffer (FIG. 12S7). .

At this time, the ready / busy signal of the recording medium is bu
In the case of sy (Fig. 12 S9), the first time until ready
The compressed data in the buffer is expanded (see FIG. 12S1).
0), the dead time is effectively used, and the time required for image reproduction is minimized.

When the recording medium side becomes ready, interrupt,
The data decompression process of the first buffer is interrupted by a flag or the like, and the data reading to the second buffer is restarted (see FIG. 1).
2S11). In this way, when all the data in the first buffer has been expanded, the compressed data is then read into the second buffer. Therefore, this time, the data in the second buffer is decompressed and the compressed data is read into the first buffer.
By repeating such processing, the entire image is expanded.

Further, a schematic description of this situation is as shown in FIG. That is, the first buffer and the second buffer are repeated as in the initial state → state 1 → state 2 → state 3 → state 4 → state 5 → state 6 → state 3 →.
It operates to process alternately.

The image data thus expanded is written in the frame memory. After that, when a command to display an image is issued to the signal processing unit and the memory controller unit, the memory controller unit reads the image data from the frame memory unit and outputs the analog image to the NTSC output terminal via the signal processing unit. To do.

As described above, the decompression of compressed data and the reading from the recording medium can be efficiently performed by utilizing the mutual waiting time. Therefore, the total processing time can be minimized. Then, when compressing / decompressing an image, the size of the buffer memory required for compressing / decompressing an image is changed from the conventional one compressed image data (about 128 kB) to the minimum size (4 k
It has become possible to reduce the size to B × 2).

<Embodiment for Achieving Sixth Object> FIG. 15 is a functional block diagram showing an overall schematic configuration of a digital still camera according to an embodiment for achieving the sixth object of the present invention. is there.

In the digital still camera shown in FIG. 15, an optical image obtained through an optical system including a lens 1, an iris diaphragm 2 and the like is an image pickup element 3 such as a CCD.
Is formed on the light receiving surface of Also, at this time, this lens 1
And the iris diaphragm 2 are the focus drive circuit 1 respectively.
6 and the diaphragm drive circuit 15.

Here, the image pickup device 3 photoelectrically converts the light image formed on the light receiving surface into a charge amount, and outputs an analog image signal in response to a transfer pulse from the CCD drive circuit 19.
The output analog image signal is supplied to the preprocessing circuit 4
In, noise is reduced by CDS (correlated double sampling) processing, gain is adjusted by AGC, and secondary processing for expanding the dynamic range is performed.

After being converted into a digital image signal by the A / D converter 5, the signal processing circuit 6 performs brightness processing and color processing to obtain a digital video signal (for example, a brightness signal (Y) and a color difference signal ( Cr, Cb)) and output to the memory controller 7.

On the other hand, the signal processing circuit 6 also has a built-in D / A converter, and a colorized video signal input from the A / D converter 5 side and an inverse input from the memory controller 7. It is also possible to output the image data as an analog video signal.

These functions are switched by exchanging data with the main microcomputer 8, and the exposure information, focus signal, and white balance information of the image pickup device signal can be output to the main microcomputer 8 as necessary.

The main microcomputer 8 is mainly used for photographing,
It controls the sequence of recording and playback, and also performs compressed playback of captured images and serial port transmission with external devices as necessary. Here, CCITT and ISO are used as image compression.
The JPEG method or the JBIG method, which is standardized by the above, is used.

Then, the memory controller 7 accumulates the digital image data input from the signal processing circuit 6 in the frame memory 9 and, conversely, outputs the image data in the frame memory 9 to the signal processing circuit 6.

The frame memory 9 is an image memory capable of accumulating image data of at least one screen. For example, VRAM, SRAM, DRAM or the like is generally used. Here, a VRAM that can operate independently of the CPU bus is used. doing.

The image storage memory 10 is a memory built in the main body, and stores the image data stored in the frame memory 9 after being subjected to image compression processing or the like by the main microcomputer 8. As the image storage memory 10,
For example, SRAM, DRAM, EEPROM or the like is used, but EEPROM is preferable in consideration of storing the image data in the memory.

The PC card controller (PCMCIA controller) 11 is a PC memory card (hereinafter simply referred to as PC
An external recording medium such as a card) and the main microcomputer 8 are connected to each other, and an image stored in the frame memory 9 is subjected to an image compression process or the like by the main microcomputer 8 and then, via the controller 11. And is recorded in an external storage medium. The external storage PC card connected via the PC card controller 11 is an SRAM.
A card, a DRAM card, an EEPROM card or the like can be used, and a modem card or an ISDN card can be used to directly transfer image data to a remote storage medium via a public line.

The strobe 12 is designed so that the light emission timing can be obtained by the main microcomputer 8 which controls the photographing sequence. The serial port driver 13 performs signal conversion for performing information transmission between the camera body and information between external devices. As the serial transmission means, RS23
There are recommended standards for performing serial communication such as 2C and RS422A, but here, RS232C is used.

The sub-microcomputer 14 controls man-machine interfaces such as operation switches of the camera body and a liquid crystal display, and transmits information to the main microcomputer 8 as necessary. Here, a serial input / output terminal is used for transmitting information to and from the main microcomputer 8. It also has a built-in clock function and controls the auto date.
The insertion / extraction state of the flash memory is also detected by referring to the card detection signal line.

The diaphragm drive unit 15 is composed of, for example, an auto iris, and changes the optical diaphragm value of the diaphragm 2 under the control of the main microcomputer 8. The focus drive unit 16 is composed of, for example, a stepping motor,
The lens position is changed under the control of the main microcomputer 8 so that the optical focus surface of the subject is properly adjusted on the image pickup device 3. The liquid crystal display unit 18 is the sub-microcomputer 1
4 is a display unit that is connected to the display unit 4 and displays various information such as shooting information.

The flash memory controller 20 connects the flash memory card, which is not in the above-mentioned PC card format, and the main microcomputer 8, and the image photographed in the frame memory 9 is subjected to image compression processing or the like on the main microcomputer 8. Then, the data is recorded on the external recording medium via the flash memory controller 20.
In the configuration shown in FIG. 15, the main microcomputer 8 performs image compression and decompression, but CP
A dedicated circuit for compression / expansion may be arranged on the U bus.

The flash memory used here can be connected to the sub-microcomputer 1 by connecting a spare signal line or GND line.
The insertion / removal can be detected from the 4 side. The card detection signal line connected between the card connector and the sub-microcomputer is pulled up by a resistor.
When the card is inserted, the signal drops to GND, and the sub-microcomputer 14 can know that the card is inserted or removed.

Now, a series of basic operations from photographing to memory recording will be described. The operation mode of the camera is set from various switch information connected to the sub-microcomputer 14, and the information for photographing is output to the main microcomputer 8 as serial information. Depending on this information, the main microcomputer 8
Sets the memory controller 7, the signal processing circuit 6, the preprocessing circuit 4, and if necessary, the PC card controller 11, the flash memory controller 20, and the serial port driver 13.

When the release switch on the sub-microcomputer 14 is pressed halfway and the S1 signal is turned on, the sub-microcomputer 14 section sends the information to the main microcomputer 8. When the main microcomputer 8 learns that the S1 signal has become active, it issues an image input command to the signal processing circuit 6,
Operates the image sensor 3, the pre-process circuit 4, and the A / D converter 5 to receive a captured image. The signal processing circuit 6 performs basic signal processing on the received captured image data, and then creates focus information from the high frequency component of the brightness data and exposure data from the low frequency component.

The main microcomputer 8 reads these data from the signal processing circuit 6 and performs aperture drive and focus drive as required, and further performs gain control of preprocess AGC amplification until proper exposure and focus are obtained. Make you converge. Also, depending on the operation mode, the signal processing circuit 6 outputs an analog image signal and outputs it as an NTSC signal to an external monitor.

After the exposure value and focus converge to appropriate values,
When the release switch is fully pressed by the sub-microcomputer 14 to the main microcomputer 8 to turn on the S2 signal, the main microcomputer 8 outputs a fetch command to the memory controller 7. Further, if necessary, a light emission signal is also output to the strobe unit at the field timing of the captured image. When the memory controller 7 receives an image capture command,
The synchronization signal from the signal processing circuit 6 is detected, and the image data in the YCrCb format or the like output from the signal processing circuit 6 is taken into the frame memory at a predetermined timing. When the capture of the image is completed in the frame memory unit, the memory controller 7 displays a status indicating that the capture is completed, and the main microcomputer 8 reads this to know that the photographing is completed on the main microcomputer side.

After the photographing is completed, the main microcomputer 8 compresses the image as required, and stores it in the image storage memory.
Image data is transferred to an externally connected PC card or flash memory, or to a personal computer connected to an external serial port. The size of the compressed image data generated by compression here changes depending on the frequency component of the captured image. In addition, the main microcomputer 8
At the same time as this image compression, generates a thumbnail image to be described later and transfers it together with the compressed image data.

In the reproduction display operation, the main microcomputer 8
Image data is read from the image storage memory 10, an externally connected PC card or flash memory, or a personal computer connected to an external serial port, the image is decompressed as necessary, and written in the frame memory. .

Since it is possible that the PC card or flash memory contains image data that is not image data or that cannot be reproduced by this system, it is checked whether each file can be reproduced when the card is inserted and recorded in the table. . This operation will be described later.

After that, when a command for displaying an image is issued to the signal processing circuit 6 and the memory controller 7, the memory controller 7 reads the image data from the frame memory unit and outputs it to the NTSC output terminal via the signal processing circuit 6. The analog signal of the image is output.

As described above, the basic functions of the camera such as photographing, recording, reproducing, displaying and transmitting are achieved. Here, the characteristic portion that achieves the above-described sixth object will be described.

After the photographing is finished, the main microcomputer 8 compresses the image as necessary, and stores it in the image storage memory.
Image data is transferred to an externally connected PC card or a personal computer connected to an external serial port.

At the time of this image compression, the main microcomputer 8 is made to generate a reduced image called a thumbnail image. That is, DCT conversion is performed on a fixed area of a plurality of pixels of the original image data to generate DC component data. If the fixed area is the same as the minimum unit (for example, 8 × 8 pixels) for performing the image compression described above, the processing becomes simple.

The DC generated in each of these areas
Reduced image (thumbnail image) data is generated by collecting the component data. Then, this thumbnail image data is stored in the same data file as the compressed image data,
Alternatively, it is recorded in association.

FIG. 16 shows the case where the original image has 32 × 32 pixels (FIG. 16 (a)), and for each 8 pixels D
The C component is extracted (FIG. 16 (b)), and these are aggregated to generate a thumbnail image (FIG. 16 (c)).

The DCT conversion is a kind of frequency conversion. Therefore, the DC component value generated after conversion represents an average value of the converted area. The AC component represents the spatial frequency distribution of the image.

When confirming the image contents, the main microcomputer 8 reads the thumbnail image data from the image data file and outputs it as an NTSC video signal.
When confirming the image contents, it is sufficient to reproduce the thumbnail image as it is, and it is not necessary to decompress the original compressed image data, and it is possible to quickly confirm what kind of image is recorded in the data file. I can. That is, since the thumbnail image has a smaller size than the original image, it can be processed at high speed.

Here, a case where the size of the original image data is 640 × 80 pixels in the case of a frame image will be described with reference to the schematic diagram of thumbnail images in FIG. At this time, the thumbnail image (FIG. 17C) generated from the field image is displayed after being interpolated by the horizontal line in the main microcomputer 8 (FIG. 17D). By doing so, it is possible to display thumbnail images of uniform size with respect to the original image in which the frame image (FIG. 17A) and the field image (FIG. 17B) are mixed.

Displaying a plurality of thumbnail images on one screen so that the contents of a plurality of original images can be viewed on the TV monitor will be referred to as index reproduction here. In the index reproduction, only the thumbnail data attached to the compressed image data file is read and displayed. Therefore, it is possible to display at high speed without requiring decompression processing. FIG. 18 schematically shows a state in which 16 thumbnail images are index-reproduced.

By doing so, it becomes possible to display thumbnail images of a plurality of compressed image data recorded on the recording medium in a short time. Further, similarly, it becomes possible to display the thumbnail images of the plurality of compressed image data recorded on the recording medium as an index in a short time.

As shown in FIG. 19A, consider a case where a thumbnail image is displayed as a child screen in picture-in-picture (PinP) display during normal image reproduction. During this PinP display, if either the frame advancing or the frame rewinding operation is not performed within a fixed time for the thumbnail image selected and displayed as the sub screen, the main microcomputer 8 displays the sub screen of the sub screen being displayed. The original compressed image data is read from the data file, decompressed and output as an NTSC video signal. As a result, when there is no operation for a certain period of time on the small screen side, the original image data of the small screen thumbnail image is displayed on the entire screen (FIG. 19B).

By setting the fixed period of time to about 3 to 5 seconds, it is possible to operate without feeling uncomfortable. Further, it is possible to change the value other than the predetermined initial value on the user side and to stop this automatic switching operation.

By setting in this way, the reproduced image can be viewed with a few switch operations. Further, it is possible to omit the switch for switching the thumbnail image of the child screen to the parent screen.

[0224]

As described in detail above, when the defective block occurs in the flash memory as shown in the inventions of claims 1 to 9 for achieving the first object,
Disable the corresponding bad block, have a spare block in the memory to replace the bad block,
When the spare block is used up, by making all the data in the memory read-only, it is possible to realize a digital still camera capable of avoiding the inability to write a captured image due to block destruction of the flash memory.

As described above in detail, as described in the inventions of claims 10 to 14 for achieving the second object, a recording medium in which various kinds of files are mixed is attached to the camera. If a file is displayed on the camera, it is checked whether it is a file that can be displayed on the camera when the recording medium is installed, and only the files that can be displayed are recorded in the table. In this case, the user does not have to select the file one by one, and it is not necessary to determine whether the file can be displayed after the file is specified, reducing the time to display the image file. It is possible to realize a digital still camera that can do this.

As described in detail above, as described in the invention of claim 15 for achieving the third object, the recording medium is attached / detached by using an unused signal line without using a dedicated signal line. By detecting with this method, the existing signal line of the recording medium can be used as the signal for detection of attachment / detachment, and the configuration can be simplified. It is possible to realize a digital still camera that does not require a detection mechanism.

As described in detail above, as shown in the inventions of claims 16 to 17 for achieving the fourth object, a certain maximum value is set for the size of one image data. By calculating the remaining number of shootable images, it is possible to realize a digital still camera capable of predicting the remaining number of shootable images for image data whose image data amount is not constant.

As described in detail above, as described in the invention of claim 18 to claim 21 for achieving the fifth object, a plurality of capacities corresponding to the capacities of recording and reproducing of the recording medium are provided. The buffer memory having the area of is used, and the time required for each process is used to alternately use the plurality of areas of the buffer memory, so that the size of the buffer memory required for recording and reproducing accompanied by compression and expansion of the image It is possible to realize a digital still camera capable of minimizing the processing time and the processing time.

As described in detail above, as described in the invention of claims 22 to 25, which achieves the sixth object, a pixel in which a DC component of each pixel of a certain area is extracted in a data file is extracted. By having the thumbnail image data in which the thumbnail images are collected, it becomes possible to display the thumbnail images of the plurality of compressed image data recorded on the recording medium in a short time.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of a digital still camera for achieving a first object.

FIG. 2 is an explanatory diagram showing a state of blocks generated according to a format.

FIG. 3 is a configuration diagram showing a configuration of a digital still camera for achieving the second object.

FIG. 4 is an explanatory diagram showing a state of a table storing displayable name file names.

FIG. 5 is a configuration diagram showing a configuration of card insertion / removal detection.

FIG. 6 is an explanatory diagram showing how the remaining amount of the flash memory is predicted.

FIG. 7 is an explanatory diagram showing how the remaining amount of the flash memory is predicted.

FIG. 8 is a configuration diagram showing a configuration of a digital still camera for achieving a fifth object.

FIG. 9 is a flowchart showing an outline of processing for minimizing the size of the buffer memory required for recording with image compression / expansion.

FIG. 10 is a flowchart showing a state of image compression.

FIG. 11 is a schematic diagram showing an outline of processing for minimizing the size of the buffer memory required for recording with image compression / expansion.

FIG. 12 is a flowchart showing an outline of processing for minimizing the size of a buffer memory required for reproduction accompanied by compression / expansion of an image. FIG.

FIG. 13 is a flowchart showing a state of image expansion.

FIG. 14 is a schematic diagram showing an outline of processing for minimizing the size of a buffer memory required for reproduction accompanied by compression / expansion of an image.

FIG. 15 is a configuration diagram showing a configuration of a digital still camera for achieving a sixth object.

FIG. 16 is an explanatory diagram schematically showing how a thumbnail image is generated.

FIG. 17 is an explanatory diagram schematically showing how a thumbnail image is generated from an original image of a field image and a frame image. FIG.

FIG. 18 is an explanatory diagram showing a state of index display of thumbnail images.

FIG. 19 is a diagram showing a thumbnail image in PinP display.

[Explanation of Codes] 1 Lens 2 Aperture 3 Image Sensor 4 Pre-Process Circuit 5 A / D Converter 6 Signal Processing Circuit 7 Memory Controller 8 Main Microcomputer 9 Frame Memory 10 Image Storage Memory 11 PC Card Controller 12 Strobe 13 Serial Port Driver 14 Sub-microcomputer 15 Aperture drive circuit 16 Focus drive circuit 17 Video amplifier 18 Liquid crystal display unit 19 CCD drive circuit

Front page continuation (72) Inventor Tadaaki Yoneda 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica Stock Company

Claims (25)

[Claims] 1. A digital still camera having means for converting a captured optical image into a digital signal, and means for recording the image data converted into the digital signal in a memory inside the camera or a memory inside a recording medium, The memory is divided into blocks of a predetermined capacity,
Further, a data block for data recording and a spare spare block are provided, and when a defective block occurs in the memory, the defective block is disabled and the spare block is used, and when the spare block is used up. Is a digital still camera in which all the data in the memory are read-only. 2. In the digital still camera,
2. The digital still camera according to claim 1, further comprising means for notifying a user that the memory is read-only when the memory is read-only. 3. In the digital still camera,
2. The digital still camera according to claim 1, wherein when the preset number of spare blocks is used up, the number of spare blocks in the memory is increased. 4. In the digital still camera,
2. The digital still camera according to claim 1, wherein the allocation of spare blocks in the memory is increased when the memory is formatted. 5. In the digital still camera,
2. The digital still camera according to claim 1, wherein the digital still camera notifies a user that the allocation of spare blocks in the memory has been increased. 6. In the digital still camera,
A digital still camera characterized in that a defective block is prohibited from use and the user is notified that the number of valid blocks has decreased. 7. In the digital still camera,
2. The non-recorded block is searched for when a defect occurs in the middle of writing data after the preset number of spare blocks has been used up, and recording is performed again in the non-recorded block. Digital still camera. 8. In the digital still camera,
2. The digital still camera according to claim 1, wherein the physical address of an unrecorded block is acquired in advance before writing, and if a defect occurs during the writing of data, recording is re-performed in the acquired unrecorded block. 9. In the digital still camera,
After the preset number of spare blocks has been used up, the physical address of an unrecorded block should be acquired in advance before writing, and if a defect occurs during the writing of data, recording should be performed again on the acquired unrecorded block. The digital still camera according to claim 1, wherein: 10. A unit for converting a captured optical image into a digital signal, a unit for recording the image data converted into the digital signal in a memory in a recording medium, and a unit for storing the recorded image data in a camera. Whether the file data recorded in the recording medium when the recording medium is mounted on the camera can be displayed by the digital still camera. A digital still camera characterized by examining. 11. The digital still camera according to claim 10, further comprising a table for storing data necessary for selecting a displayable file in the digital still camera. 12. The digital still camera according to claim 10, further comprising a selection unit that handles only files that can display images, in the digital still camera. 13. The digital still camera according to claim 10, further comprising a table for storing data necessary for selecting a file capable of displaying an image in a photographing order in the digital still camera. 14. The digital still camera according to claim 10, further comprising a selection unit that uses additional data of an image file to select a displayable file. 15. The digital still camera according to claim 10, wherein the attachment / detachment of the recording medium is detected using an unused signal line instead of using a dedicated signal line. 16. A data storage device in a recording medium, or in the digital still camera equipped with a built-in data storage device, when the amount of image data is not constant, one of A digital still camera characterized in that the data amount of one image is calculated assuming a certain maximum value. 17. The digital still camera does not record image data when the recordable capacity in the data storage device becomes smaller than the data amount of the image assumed to be the certain maximum value. The digital still camera according to claim 16. 18. A conversion means for converting a captured optical image into a digital image signal, a compression means for compressing the digital image signal to generate compressed image data, and a recording means for recording the compressed image data on a recording medium. The recording means comprises a buffer memory having a plurality of areas having a capacity corresponding to a capacity of recording and reproducing of the recording medium, and using the plurality of areas alternately, recording from the buffer memory to the recording medium is performed. A digital still camera characterized in that the compressed image data generated by the compression means is recorded in a buffer memory. 19. A conversion means for converting a captured optical image into a digital image signal, a compression means for compressing the digital image signal to generate compressed image data, and a recording means for recording the compressed image data on a recording medium. The recording means comprises a buffer memory having a plurality of areas each having a capacity corresponding to a recording / reproducing unit of the recording medium, and the time required for generating the compressed image data by the compressing means or the buffer memory The plurality of areas of the buffer memory are alternately used by utilizing the time required for recording to the recording medium, and recording from one area of the buffer memory to the recording medium and the other of the buffer memory of the compressed image data generated by the compression means. A digital still camera characterized by performing recording in the area of. 20. Recording means for converting a photographed optical image into a digital image signal, compressing the digital image signal to generate compressed image data, and recording the compressed image data on a recording medium; The reading means reads the compressed image data recorded on the medium, and the expanding means for expanding the compressed image data to generate a digital image signal. The reading means has a capacity which is a unit of recording and reproducing of the recording medium. A digital memory characterized by comprising a buffer memory having a plurality of areas of corresponding capacity, and alternately using the plurality of areas to perform reading from the recording medium to the buffer memory and reading from the buffer memory to the expanding means. Still camera. 21. Recording means for converting a photographed optical image into a digital image signal, compressing the digital image signal to generate compressed image data, and recording the compressed image data on a recording medium; The reading means reads the compressed image data recorded on the medium, and the expanding means for expanding the compressed image data to generate a digital image signal. The reading means has a capacity which is a unit of recording and reproducing of the recording medium. A buffer memory having a plurality of areas of corresponding capacity is provided, and the plurality of areas of the buffer memory are alternately used by utilizing the time required for reading from the recording medium to the buffer memory or the time required for the expansion processing by the expansion means. , Reading from the recording medium to one area of the buffer memory and reading from the other area of the buffer memory to the decompression means. A digital still camera, which is characterized in that it starts and ends. 22. A conversion means for converting a photographed optical image into a digital image signal, a compression means for compressing the digital image signal to generate compressed image data, and a recording / reproduction for recording and reproducing the compressed image data on a recording medium. Means and decompression means for decompressing the compressed image data recorded on the recording medium,
A digital still camera, comprising: an output unit that outputs the expanded image data as a video signal, wherein the compression unit generates compressed image data, performs DCT conversion on the digital image signal, and converts the DC component thereof. A digital still camera characterized in that thumbnail images are generated by assembling. 23. A control means for determining whether the compressed image data recorded on the recording medium is a field image or a frame image, and generating a thumbnail image in which the thumbnail image recorded together with the field image is interpolated line by line 23. The digital still camera according to claim 22, wherein: 24. A control means for reading a plurality of thumbnail data recorded together with a plurality of compressed image data on a recording medium to generate an image in which a plurality of thumbnail images are arranged on one screen. 22. A digital still camera according to item 22. 25. When a thumbnail image different from the image being played back is displayed in picture-in-picture as a sub-screen, and if either the frame advancing or the frame rewinding operation for the sub-screen is not performed within a certain time, 23. The digital still camera according to claim 22, further comprising control means for reading out compressed image data corresponding to the thumbnail image of the small screen and expanding and reproducing the compressed image data.