JPH09326994A - Electronic camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control optionally a recording frame number by varying a parameter of coded compression based on a data capacity of compressed image data to be detected when a storage available capacity reaches a set capacity or below. SOLUTION: A controller 8 monitors a recording available capacity and when the capacity reaches a capacity set by the user or set fixedly in a program, output of compressed image data stored in a buffer memory 4 to an I/F 5 is once stopped. An object data capacity of a compressed image size of one frame is compared with data in a data capacity detection section 10 to allow a parameter setting section 9 to set a compression parameter. The parameter setting section 9 sets a compression parameter of a CODEC processing section 8 again and the compressed image data subject to compression processing are written in a data buffer memory 4. When the storage available capacity reaches a setting value or below in this way, the number of frames is controlled by revising the parameter of coding compression.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic camera,
In particular, the present invention relates to a control method for storing compressed image data using a large capacity storage device.

[0002]

2. Description of the Related Art In recent years, with the increase in CPU processing capacity and the increase in capacity of storage devices such as HDDs, computer devices (personal computers, hereinafter referred to as PCs) can handle images such as still images and moving images. It became possible. Along with this, an electronic camera has attracted attention as one of image input devices for a PC due to its ease of photographing, and a number of products have been developed. This electronic camera records image data in the form of digital data in a storage means such as a semiconductor memory. The image data recorded in the electronic camera is transferred to a PC and used for attachment to documents and creation of presentation materials.

In recent electronic cameras, due to improvements in image compression technology, image data is compressed by a compression method using, for example, DCT (discrete cosine transform), and a storage device such as a PC card in a state where the data amount is reduced. The method of recording is adopted. A typical example of this compression method is the JPEG method which is a still image compression technology. this is,
The amount of data is reduced by quantizing the DCT-transformed image data with a coefficient α and Huffman coding.

In the case of using the JPEG method, if the coefficient α used for quantization is fixed, there is a problem that the amount of compressed image data significantly changes depending on the pattern to be photographed. For this reason, when recording in a storage device having a limited capacity, a technique for maintaining the target amount of compressed image data by performing the compression process a plurality of times by changing the coefficient α for the purpose of keeping the number of captured images constant. Some have adopted. This conventional technique is described, for example, in Japanese Patent Laid-Open No. 5-64143.

[0005]

However, in recent years, the capacity of memory devices has been increasing, and PC card type HDs have been developed.
When D and the like have come to be adopted in a storage device of an electronic camera, the following problems are expected to occur.

A conventional technique using such a PC card type HDD as a storage device of an electronic camera is, for example, "Symposia on Fine Imaging October"
3 to 6, 1996 ”, pages 73 to 76, and the storage capacity of the HDD PC card used here is 1
It is 31 MB.

Here, the amount of compressed image data to be recorded is calculated as follows. Original image is generally 640
(H) × 480 (V), the ratio of the luminance signal (Y) and the color difference signals (Cr, Cb) is Y: Cr: Cb = 4: 2: 2,
If the data gradation is 8 bits, the original image data amount is 640
It can be calculated by × 480 × 2, 614400 bytes, that is, 6
It will be 00 Kbytes. If the target compression rate is 1/10,
The amount of compressed image data for one sheet is 60 Kbytes.

Therefore, the compressed image data that can be stored in the PC card type HDD is 131 × 1024/60, which is approximately 2
It is 235 sheets. When handling a large amount of compressed image data in this way, it is not necessary to accurately grasp the current number of shootable images. Furthermore, in order to keep the amount of compressed image data at the target amount, the coefficient α is changed to perform multiple compression processes. To do
It is also disadvantageous in terms of processing time and power consumption.

The present invention has been made in view of the above points,
The purpose of this is that when the storage capacity of a storage device such as a PC card is sufficiently large, the data capacity of compressed image data is not controlled, the processing time, power, etc. are suppressed and the storage capacity is reduced. At this time, the number of recording frames is controlled arbitrarily.

[0010]

In order to achieve the above object, an electronic camera according to the present invention has means for monitoring the storable capacity of a storage means such as an HDD, and means for detecting the data capacity of compressed image data. When the storable capacity is equal to or smaller than the already set capacity, the encoding compression parameter is changed based on the data capacity of the detected compressed image data. The compression process is performed so that the amount can be kept constant.

Further, the electronic camera has a plurality of encoding / compressing methods, can generate compressed image data by the plurality of encoding / compressing methods, and stores at least one encoding / compressing method. When the available capacity becomes less than or equal to the already set capacity, the coding compression parameter is changed based on the data capacity of the detected compressed image data,
The compression processing is performed so that the amount of compressed image data falls within a fixed amount.

Further, the storable capacity for starting the above-mentioned encoding / compression parameter change is set based on the number of frames that the user wants to secure last.

Further, a display means is provided, and when the storable capacity detected by the recording capacity detecting means becomes less than a predetermined amount,
It is configured to display the transition to this state.

Further, the display means displays the time when the storable capacity detected by the recording capacity detecting means becomes less than or equal to a predetermined amount.
The number of remaining recordable frames is displayed.

Furthermore, when the storage capacity is set based on the number of frames that the user wants to secure last and the remaining number of frames that can be recorded is displayed by the display means, the user again sets the number of frames that he wants to secure. The configuration is such that the compression parameters can be changed.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an electronic camera according to the first embodiment of the present invention. In FIG. 1, 1 is a camera processing unit, 2 is a frame memory, 3 is a CODEC processing unit, 4 is a buffer memory, 5 is an interface unit (hereinafter referred to as I / F), 6 is a PC card socket, and 7 is PC card (here, for example, PC card type H
DD), 8 is a controller, 9 is a parameter setting unit, 1
Reference numeral 0 is a data capacity detection unit, 11 is a storage capacity detection unit, and 12 is a control switch unit (hereinafter referred to as a control SW).

Next, the operation will be described. When the user operates an activation SW (not shown) in the control SW 12, the controller 8 starts controlling each processing unit according to the program stored in the controller 8.

The camera processing unit 1 is composed of known technical means such as a lens, an image pickup device such as a CCD (Charge Coupled Device), an A / D conversion circuit, and a digital camera signal processing circuit which are not specified here. The light imaged on the image pickup element through the lens is photoelectrically converted and subjected to digital image processing to output a digital video signal.

The digital video signal is temporarily stored in the frame memory 2 and input to the CODEC processing unit 3 by the user's operation of the recording SW (not shown) in the control SW 12. The CODEC processing unit 2 is a portion that performs a known encoding / compression process such as JPEG on a digital video signal and converts the digital video signal into compressed image data.
The digital video signal stored in is sequentially read, converted into compressed image data, and output. Here, in order to simplify the explanation, it is assumed that JPEG processing for handling a still image is used.

The compressed image data is stored in the buffer memory 4
Stored in. The I / F 5 is connected to the PC card 7 via the socket 6, reads the compressed image data stored in the buffer memory 4, converts it into the interface format of the PC card 7, and transfers it to the PC 7 card.

Such an operation is equivalent to an operation of generating and recording compressed image data in a known electronic camera that stores a still image.

Next, the data volume control of the compressed image data will be described. In addition to the above operation, the I / F 5
The status data indicating the status of the C card 7 is read and output to the recording capacity detection unit 11. The recording capacity detection unit 11 detects the recordable capacity indicating the remaining memory capacity of the PC card 7 from this state data and outputs it to the controller 8.

The controller 8 monitors the recordable capacity, and if the capacity is set to a value (hereinafter, referred to as a threshold value) which is set by the user or fixed in the program, the next time. The following processing is started from shooting.

After the above-mentioned time point, the controller 8 temporarily stops the output of the compressed image data generated by photographing and stored in the buffer memory 4 to the I / F 5, and detects the data amount of the compressed image data. Receive the data of part 10.

Next, the parameter setting unit 9 is instructed to set the compression parameter so that the target data capacity of the compressed image size of one frame does not exceed the data capacity of the compressed image data. As a result, the parameter setting unit 9 causes the CODE
The compression parameter of the C processing unit 8 is reset. After this processing is completed, the compression processing is performed again, and the compressed image data is written in the buffer memory 4.

The above-described operation is repeated a plurality of times, and after the capacity of the compressed image data to be recorded falls within the target data capacity of the compressed image size of one frame, the controller 8 causes the buffer memory 4 generated by the above-described shooting. The compressed image data stored in is output to I / F5,
It is stored in the PC card 7.

The operation of the first embodiment will be described in detail with reference to FIG. FIG. 2 shows a memory space in the PC card 7. The compressed image data is sequentially stored in the memory 13 by the user's photographing operation. At this time, since the compression parameter operation is not performed as described above up to the threshold value a, the amount of compressed image data changes depending on the pattern to be photographed. When the storable capacity of the memory 13 reaches the threshold value a, the compressed image data amount is kept constant as shown in the figure by the control described above. Here, for example, eight frames of compressed image data are stored in the area b. Therefore, if the user arbitrarily sets the threshold value a and the number of recording frames when the storable capacity becomes equal to or less than the threshold value a or the program designer sets in advance, the PC card 7 can be stored. It is possible to secure the number of recording frames when the capacity becomes small.

In the structure capable of encoding and compressing in the JPEG system and the other systems, the storage capacity of the storage means such as the above-mentioned PC card 7 is added to at least one encoding / compression method such as the JPEG system. When the number of frames becomes small, control for securing the number of recording frames may be performed.

FIG. 3 is a block diagram of an electronic camera according to a second embodiment of the present invention, in which FIG.
The same parts as those in the embodiment are designated by the same reference numerals, and the description thereof will be omitted to avoid duplication.

The second embodiment is different from the first embodiment in that a display section 14 showing the state of the electronic camera to the user is added under the control of the controller 8, and except for the following operation, Other operations are the same as those in the first embodiment.

The display unit 14 displays P by the above-mentioned operation.
The fact that the storable capacity of the C card 7 becomes equal to or less than the threshold value a and the control is switched to keep the compressed image data amount constant is displayed by a figure, a symbol, or a number.

An example of the display is shown in FIG. PC card 7
Since the storable capacity is sufficiently large until the storable capacity becomes equal to or less than the threshold value a, a display that shows an outline of the storable capacity is displayed as shown in FIG.

On the other hand, when the storable capacity becomes equal to or less than the threshold value a, the display switches to the display of the number of remaining recordable frames as shown in FIG. 4B, and the countdown display is sequentially performed by the photographing operation of the user.

FIG. 5 shows a third embodiment of the present invention. The figure schematically shows a part of the control SW 12 and the display section 13 shown in FIG.

The structure of the electronic camera according to the third embodiment is almost the same as that of the second embodiment shown in FIG. 3, except that the following control means is added.

Reference numerals 15a and 15b are display screens of the display unit 14, and the display screen 15a is a display screen when the storable capacity of the PC card 7 becomes equal to or less than the threshold value a. The number “10” is the number of recording frames set in advance by the user or the program designer when the storable capacity of the PC card 7 becomes small. Therefore, it is possible to capture another 10 frames.

At this time, when the number of frames the user wants to photograph is more than 10, the user pushes the UP-SW 16 which is a part of the control SW 12. As a result, the controller 8 controls the parameter setting unit 9 to reset the compression parameters and secure the number of shooting frames desired by the user. Reference numeral 15b is a display screen of the display unit 14 when the user wants to record another 15 frames and is reset by the above operation. The number of frames can be reset by the UP-SW 16 and the DOWN-SW 17.

[0038]

As described above, according to the present invention, when the storable capacity of the storage device such as a PC card is sufficiently large, the data capacity of the compressed image data is not controlled, and the processing time, power, etc. are suppressed. The number of recording frames can be arbitrarily controlled when the storable capacity becomes equal to or less than the threshold value a, that is, when the storable capacity becomes small.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an electronic camera according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of a memory map in a PC card according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of an electronic camera according to a second embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a display example according to a second embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a display example and the like according to a third embodiment of the present invention.

[Explanation of symbols]

 1 camera processing unit 2 frame memory 3 CODEC processing unit 4 buffer memory 5 interface unit (I / F) 6 socket 7 PC card 8 controller 9 parameter setting unit 10 data capacity detecting unit 11 recording capacity detecting unit 12 control switch unit (control SW) ) 13 memory 14 display part 15a, 15b display screen 16 UP-SW 17 DOWN-SW

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Iwasawa Awazawa 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa, Ltd. Hitachi, Ltd. multimedia system development headquarters (72) Inventor Takeshi Kitade 1410 Inada, Hitachinaka-shi, Ibaraki Stock Company Hitachi, Ltd. Visual Information Media Division

Claims (6)

[Claims] 1. An electronic camera for electronically generating image data, encoding and compressing the image data to convert the image data into compressed image data, and recording the compressed image data in a storage means. The recording capacity detecting means includes a capacity detecting means, a data capacity detecting means for detecting a data capacity of the converted compressed image data, and a compression parameter setting means for variably setting the encoding compression parameter. The electronic camera is characterized in that when the storable capacity detected by is less than or equal to a predetermined amount, the encoded image compression parameter is changed to control the compressed image data capacity. 2. An electronic camera for electronically generating image data, encoding and compressing the image data to convert the image data into compressed image data, and recording the image data in a storage means. Regarding one encoding compression method, the recording capacity detecting means for detecting the storable capacity of the storage means, the data capacity detecting means for detecting the data capacity of the converted compressed image data, and the encoding compression parameter are A compression parameter setting means for variably setting is provided, and when the storable capacity detected by the recording capacity detecting means becomes a predetermined amount or less, the encoding compression parameter is changed to control the compressed image data capacity. An electronic camera characterized by. 3. The storage device according to claim 1, wherein the predetermined amount set in advance is set to an approximate capacity corresponding to the number of frames to be recorded, and the storable capacity detected by the recording capacity detecting means is When the amount becomes less than the predetermined amount, the compressed image data is changed by changing the encoding compression parameter while monitoring the compressed image data capacity detected by the data capacity detection means and the storable capacity detected by the recording capacity detection means. An electronic camera characterized by controlling the capacity and ensuring the number of frames to be recorded. 4. The display device according to claim 1 or 2, further comprising display means for displaying a transition to this state when the storable capacity detected by the recording capacity detecting means is less than or equal to the predetermined amount. An electronic camera characterized in that 5. The display device according to claim 4, wherein the display means displays the number of remaining recordable frames from the time when the storable capacity detected by the recording capacity detecting means becomes equal to or less than the predetermined amount. A characteristic electronic camera. 6. The electronic camera according to claim 5, wherein after the display unit displays the number of recordable remaining frames, the number of recordable remaining recording frames can be changed.