JP3278147B2 - Image recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus for converting an image signal into digital data, compressing and encoding the same, and recording the same.

[Conventional technology]

Conventional image recording devices, such as still video cameras,
In this method, analog image recording was performed on a floppy disk, or digital image data compressed by a fixed-length encoding method was recorded on a semiconductor memory card.
The fixed-length encoding is a method of performing compression encoding so that the compression code amount for one screen has a fixed value.

[Problem to be Solved by the Invention] In such a conventional image signal recording method, since the capacity of the recording medium required to record one screen of image data is determined, the total number of recordings on the recording medium is guaranteed. We were able to.

However, in a digital still video camera that compresses image data by a fixed-length encoding method, in order to guarantee the image quality of the compressed image for various image data, empirically, luminance and color information must be 8 bits / It can only be compressed to about pixel. On the other hand, if the encoding method is set to a variable length, it is possible to guarantee image quality and perform efficient compression. Variable-length coding is a coding method that allows the length of the generated code to vary depending on the image.
The coding rate of ixel is obtained. However, at this time, since the total code amount changes depending on the image, it is not possible to guarantee the total number of recordings on the recording medium.

Therefore, it is very inconvenient when recording is actually performed by the recording apparatus of the variable-length coding method because it is not known in advance how many images can be recorded.

 An object of the present invention is to eliminate such a point.

[Means for solving the problem]

For such a purpose, the image recording apparatus of the present invention has a plurality of types of shooting modes, an imaging unit that captures a subject image to generate image data, and a variable length image data generated by the imaging unit. Encoding means for encoding, recording means for recording image data variable-length coded by the encoding means on a recording medium, and control means for generating information on the number of screens recordable on the recording medium. A first mode for generating information on the number of screens recordable on the recording medium based on a code amount when the image data captured by the image capturing means is encoded; A second mode for generating information on the number of screens that can be recorded on the recording medium based on a preset representative value regardless of image data captured by the And executes the first or the second mode in accordance with the mode.

〔Example〕

FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention. Other parts of the camera not directly related to the present invention,
For example, an aperture, a shutter and the like are of course provided. In FIG. 1, an optical image of a subject captured by a lens 1 is an imaging device 2 located behind, for example, a Charge-Coupled D.
evice (CCD) converts it to a video electric signal. The imaging device 2 accumulates charges corresponding to an optical image of a subject and reads out a video signal in response to a control signal given by the control unit 7. The read video signal is converted into a digital signal by the A / D converter 3. Although not shown, means for adjusting a video signal such as formation / separation of a gamma correction color signal and white balance processing are provided between the imaging device 2 and the A / D converter 3.

The video signal converted into the digital signal is stored in the image memory 4
Is stored in

The compression encoding device 5 compresses and encodes the image data read from the image memory 4 and outputs it to the recording device 6. Note that the control unit 7 is configured to control recording / reproduction through the recording device 6 using, for example, an MS-DOS command. As the compression method, for example, a variable-length code as described in “Publication Patent Publication No. 63-124680 Coding Method” or
For example, a compression method of generating a variable length code such as performing DCT conversion of an image signal and then performing entropy coding is executed.

Further, it has a function of counting the amount of compressed code without outputting the compressed code to the recording device 6. For such a function, the circuit shown in FIG. 1 has a counting circuit 16 for counting the code amount before outputting the compression-coded data to the recording device 6.

The recording device 6 has, for example, a semiconductor memory or a tape-shaped recording medium, can exchange information with the control unit, and can write and read arbitrary digital data to an arbitrary physical address on the recording medium. It also has a function of counting the free space of the recording medium.

The control unit 7 controls the functions of the devices 2 to 6 and integrates the entire functions. In particular, it is possible to manage the image data file on the recording medium through the recording device.

That is, the control unit 7 has a function of linking file information to a physical address on a recording medium as performed by a DOS (Disk Operating System) implemented in a computer system. Therefore, the control unit 7 can manage how the file (= image compressed data) is recorded on the recording medium, and can also manage the free space. If the compression code needs to be divided into a plurality of recording units in a small recording unit and stored, the control unit specifies the physical address and the data length on the medium for each recording unit and records the compression code in the recording device 6. Let it. When arranging one image file at a plurality of positions on the recording medium, the control unit 7 also records information indicating how the image files are arranged on the recording medium.

The MMIF (man-machine interface) 8 includes a release (SW1, SW2) and other operation members 9 for operating a switch, which will be described later, and a display device 10 such as a Finder display, an external LCD display, and a buzzer.

The number of images that can be taken during actual shooting is displayed in the following procedure.

This procedure will be described with reference to the flowchart of FIG.

First, at the beginning of the flowchart, the control unit 7 outputs a command of DIR, CHK DSK to the recording device 6 to output the free space from the recording device (S1). When the shutter button is half-pressed (SW1 ON) during shooting, the control unit drives the lens 1 and focuses.
By operating the aperture, the shutter, etc., the image pickup device is exposed (S5) and the image information is fetched into the memory (S7) and the operations from the compression encoding (S9) are performed. And a compression code counting circuit
The code amount of the image data is counted by 16. On the other hand, the free space is counted by the recording device, and the number of shootable images for the image to be shot is calculated from both values (S11). For example, the number of images that can be shot is calculated by dividing the free space by the code amount of the image data. The value obtained by the calculation is notified to the user by the display device 10 provided in the finder (S13). Such display is continued while SW1 is turned on (S15, S17). Of course, when the shutter button is pressed further deeply, the flow of the image actually taken and recorded is branched from S17 to S19, S21, S23, and the same steps as S5, S7, S9 described above are executed, and the image is captured again. It is.

If the continuous shooting mode is not selected, the flow from S25 to S3
When the selection is made, the free space of the recording medium decreases as the continuous shooting progresses, and the code amount of the image data of one screen may change. Therefore, after recording the first frame of the continuous shooting, Every time the recording of one screen is completed, the free space and the number of image codes to be recorded next are counted (S23), and the decreasing number of recordable images is continuously displayed in the finder (S2).
9).

That is, in this embodiment, when the SW2 is kept pressed and the continuous recording mode is selected, the images are successively exposed, loaded into the memory, and encoded and recorded. At that time, the remaining recordable number is calculated from the code amount of the image recorded immediately before and the free space of the recording medium at that time, and the reduced remaining recordable number is continuously and sequentially displayed in the finder.

Next, a detailed flowchart in the steps S21 and S23 in FIG. 3 will be described with reference to FIG.

FIG. 4 shows the operation performed at S23 in FIG. 1, that is, after the image data is stored in the memory 4.

In FIG. 4, first, the image signal written in the memory 4 is read out and compression-encoded by an encoding circuit 5,
The data which has been compression-encoded by the counting circuit 16 is counted (S41), and the amount of the compression code is compared with the free space of the recording medium in the recording device 6 (S43). The gate 18 is controlled so that the image signal is read out from the device 4, the data is compressed and encoded, the data is output to the recording device 6, and the recording is performed.

In this case, the control unit 7 instructs the image memory 4 to read image data, instructs the compression encoding circuit 5 to record the compression code to the compression code output recording device 6, and instructs the gate 18 to open the gate. For the recording device 6, a compression code is recorded by designating a physical address and a data length on a medium for each recording unit. The recording device 6 does not request the compression encoding circuit 5 to output data unless a recording instruction is given from the control unit 7, so that the operations of the compression encoding circuit 5 and the image memory 4 are interrupted. Accordingly, the control unit 7 specifies the physical address and the data length on the medium for each recording unit in accordance with the file format to the recording device, and instructs the recording operation, whereby the compression encoding circuit 5 and the image memory Recording can be performed while controlling the operation of No. 4.

The recording operation is completed when all the compression codes have been recorded.

FIG. 2 is a diagram showing a communication procedure between the control unit 7 and the recording device 6 described above.

In FIG. 2, D-Reg is a data output request from the recording device 6 to the control unit 7, and D-Ack indicates that the data output from the compression encoding circuit 5 to the recording device 6 is valid. This signal is output from the control unit 7 to the recording device 6. Data D _{0 to} D ₇ are 8-bit parallel data outputs output from the compression encoding circuit 5 to the recording device 6.

In FIG. 2, the control unit 7 and the recording device 6
This indicates a state in which data is output for each byte while exchanging -Req and D-Ack.

In FIG. 2, the data receiving side, that is, the recording device 6
By changing the signal D-Req from High to Low, a request is made to output data to the data output side, that is, the encoding circuit 5 (hereinafter, Transmitter). T
ransmitter outputs data on the detecting data bus (D ₀ ~D ₇₎ that D-Req becomes Low, to Low D-Ack when the value is established from High.

When D-Ack goes low, the receiver takes a signal on the data bus and returns D-Req to high. Transmitt
er stops outputting to the data bus when D-Req becomes High, and returns D-Ack to High.

Transmitte by the above Req-Ack handshake
Data transfer is performed in accordance with the convenience of both r and Receiver. Therefore, the compression encoding circuit 5 does not need to generate a compression code at a fixed transfer rate, and changing the code length according to the content of the image does not cause any problem.

When the flow branches to S47 in S43, the control unit cannot perform recording on the display warning device 10 in the finder in the man-machine interface 8 because the recording medium has insufficient free space. Is displayed to prompt the user to select one of the following three processes.

That is, (1) stop the recording operation. (2) replace the recording medium. (3) delete one of the image files in the currently mounted recording medium.

Therefore, the control section 7 executes the steps of S49, S51 and S53.

When (1) is selected by the user, all the operations are stopped from S49.

When (2) is selected by the user, that is, when the recording device 6 detects the exchange of the medium and reports it to the control unit 7, the process returns to S43.

When (3) is selected by the user, the control unit 7 displays how many images exist on the display device 10 (S55).
Prompt the user to enter the number of the image to be deleted. When the user inputs the number of the image to be deleted using the operation switch (S57), the control section 7 deletes the image file (S59) and returns to S43.

Incidentally, in order to detect that the medium has been replaced, a method may be used in which the recording unit mechanically detects the presence or absence of the replacement, as disclosed in JP-A-61-182669. The control unit 7 can access the information on the presence / absence via the recording device 6.

According to the control of the flowchart shown in FIG. 4 described above, even if a compression method for generating a variable-length code is used, the recording of an image is assured to the user in some form, so that the system is easy to use and can guarantee the image quality. Can be provided.

Further, according to the present embodiment, even if the variable-length coding compression method is used, the user can guarantee and inform the user of the image recording amount, that is, the remaining number of recordable images on the recording medium. Image quality can be guaranteed.

In the above-described embodiment, a so-called still video apparatus for recording a still image on a medium has been described as an example. However, the present invention is not limited to such an apparatus, and can be applied to, for example, a facsimile apparatus and an image electronic file apparatus.

Further, as the variable length coding method of the compression coding method in the present embodiment, other various methods may be adopted.

For example, a case where entropy coding is performed on DCT-coded data may be used.

Further, in the present embodiment, the recording device 6 uses MS-DOS O
Although the data storage device is driven by the S system, the present invention is not limited to this, and may be another type of medium, for example, a semiconductor or a tape-shaped medium.

Considering a floppy disk as a recording medium, it is sufficiently possible to realize a capacity of 5 MByte with a 2-inch floppy disk by using a perpendicular magnetization recording method.
In this case, the present embodiment can guarantee the standard 55 TV field images and a minimum of 22 TV field images on the floppy disk.

In the present embodiment, as a means for generating information on the storable capacity of the storage means, the commands DIR and CHK DSK from the control unit 7 to the recording device 6 are used. However, the present invention is not limited to this. That is, when a tape is used as the medium, the control unit 7 may actually detect the actual recording area on the tape.

〔The invention's effect〕

As described above, according to the present invention, the first mode for generating information on the number of screens that can be recorded on the recording medium based on the code amount when the captured image data is encoded, and a preset mode Since the second mode for generating information on the number of screens recordable on the recording medium based on the representative value is executed according to the shooting mode, the number of recordable screens can be guaranteed with higher accuracy. .

For example, if the first mode is executed in a shooting mode having a high correlation between screens such as a continuous shooting mode, the number of recordable screens can be guaranteed with higher accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an apparatus according to an embodiment of the present invention, FIG. 2 is a timing chart showing the operation of the apparatus shown in FIG. 1, and FIG. 3 shows the operation of the apparatus shown in FIG. Flowchart FIG. 4 is a flow chart showing a part of the details of the flow chart of FIG. 1: 1: lens 2: CCD 3: A / D converter 4: image memory 5: compression encoding circuit 6: recording device 7: control unit 8: Display device 9: Operation switch

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H04N 5/76-5/775 H04N 5/907-5/956 H04N 1/41

Claims (1)

(57) [Claims] An imaging unit having a plurality of types of imaging modes and capturing an image of a subject to generate image data; an encoding unit for performing variable length encoding on the image data generated by the imaging unit; Recording means for recording the image data variable-length coded by the encoding means on a recording medium; and control means for generating information on the number of screens recordable on the recording medium, wherein the control means A first mode for generating information about the number of screens that can be recorded on the recording medium based on the code amount when the image data captured by the imager is encoded, regardless of the image data captured by the imager. A second mode for generating information on the number of screens that can be recorded on the recording medium based on a preset representative value, and wherein the first or the second mode is performed according to the shooting mode. 2. An image recording apparatus, wherein the image recording apparatus executes two modes.