JPH03240384A - Digital electronic still camera - Google Patents

Abstract

PURPOSE:To attain effective use of a memory card by setting the compression rate of picture data depending on information relating the compression of a memory card. CONSTITUTION:A ROM 4a storing in advance a storage capacity of a picture memory is built in a memory card 4. The information of the storage capacity in the ROM 4a is read by a CPU 1. The CPU 1 calculates the compression rate from the information of the read storage capacity. The compression rate is inputted to a compression circuit 11. The circuit 11 applies the compression processing of the digital picture data based on the set compression rate. Through the constitution above, when a release switch 13 is closed, an optical image of an object A becomes a still picture signal, which is converted into a digital signal and stored in an internal memory 9. The digital picture data in the memory 9 is transferred to a picture processing circuit 10, in which a luminance signal and a color difference signal are generated and the signals are subject to data compression by the circuit 11 and stored once in the memory 9. Then the signal is stored in a prescribed storage area of the card 4 by using a control signal from the CPU 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a digital electronic still camera, and more particularly to a digital electronic still camera in which digital image data is compressed and stored in a solid-state memory such as a memory card.

[Conventional technology]

Conventionally, for example, Japanese Unexamined Patent Publication No. 59-183582 discloses a method that not only ensures the portability and reliability of electronic still cameras, but also prevents deterioration in the quality of recorded images and allows stable, high-quality captured images to be instantly reproduced on an external playback device. In order to be able to reproduce the digital image data obtained by A/D converting the image signal captured by the solid-state image sensor, a removable memory means such as S
A method has been proposed in which information is stored in a card-type or cartridge-type memory means having a built-in rewritable semiconductor memory such as a RAM.

Furthermore, Japanese Patent Laid-Open No. 63-286078 discloses that in order to effectively utilize external memory means with different storage capacities, digital image data can be stored as still images for each frame by selecting compression or non-compression. A method for storing digital image data has been proposed.

[Problem to be solved by the invention]

By the way, the above card type removable memory means (
There are many types of memory cards (hereinafter referred to as memory cards) with different storage capacities, and the number of still images that can be stored differs depending on the memory card. For example, if the amount of image information for one still image is set to 200, a 128-byte memory card cannot store a single image, and a 1MB memory card can store 5 still images. Become.

Therefore, a 128-byte memory card cannot be used unless the image data is compressed and stored.

It is extremely inconvenient that the memory card may or may not be usable depending on its storage capacity. In addition, as mentioned above, there are memory cards with different storage capacities, so if you simply switch between compressed and uncompressed modes and store them, it is not possible to obtain the appropriate number of shots depending on the memory card's storage capacity. I couldn't enjoy shooting with peace of mind.

The present invention has been made in view of the above problems, and it is possible to set a suitable compression ratio according to the storage capacity of a memory card.
An object of the present invention is to provide a digital electronic still camera in which image data compressed at a desired compression rate is stored in a memory card.

[Means to solve the problem]

In order to solve the above problems, the present invention converts an image signal captured by an imaging means into digital image data,
A digital electronic still camera in which the digital image data is stored in a wearable external storage means, comprising a reading means for reading out information regarding data compression from the storage means having information regarding the data compression, and a compression means for compressing the digital image data. and compression rate setting means for setting the compression rate of the compression means based on the read information regarding data compression.

Preferably, a compression rate changing means is provided in the main body of the digital electronic still camera, so that the automatically set compression rate can be changed.

The information regarding data compression may be, for example, the storage capacity of the storage means or the compression ratio itself.

Further, when the information regarding data compression in the storage means is a compression ratio, it is preferable that the storage means is provided with a setting means that can set the compression ratio so that the compression ratio can be set changeably.

In addition, when the storage means is attached to the camera body, when the power is turned on, data other than image data is stored in the storage means.
Preferably, information including information regarding data compression is read out, and the compression rate is set from the information regarding data compression.

[Effect]

In the digital electronic still camera configured as described above, when the removable storage means is attached, information regarding data compression is read from the storage means, and a predetermined compression ratio is automatically determined from the information regarding data compression. is set. Digital image data generated from an image signal captured by the imaging means is compressed at the predetermined compression rate and stored in the storage means.

Further, the compression rate set when the storage means is attached is changed to the compression rate instructed by the compression rate changing means provided in the camera body.

Further, the compression ratio of the storage means is set to a value instructed by a compression ratio setting means provided in the storage means.

Furthermore, when the power is turned on with the storage means attached to the camera body, information other than image data including information regarding data compression is read from the storage means, and the compression rate is determined from the information regarding data compression. Set.

〔Example〕

An embodiment of the digital electronic still camera according to the present invention will be described below.

FIG. 1 is a system configuration diagram of an embodiment of a digital electronic still camera using a memory card.

The digital electronic still camera shown in the figure performs shooting operations,
A system controller 1 (hereinafter referred to as CPU) that centrally controls image processing, human output of image data, etc. +7) A system controller 1 (hereinafter referred to as CPU) that centrally controls operations, an imaging unit 2 that photographs subject A, and performs predetermined image processing on the captured image signal. a digital arithmetic processing unit 3 that performs data compression and generates compressed digital still image data; and a removable memory card 4 that stores the compressed digital image data and has a built-in image memory such as SRAM. It is composed of. The CPU, the imaging section 2, and the digital processing section 3 are built into the camera body, and the memory card 4 is mechanically and electrically connected to the camera body through a connector 15. Further, in the figure, a switch 12 is a main switch for starting the camera, and when the switch 12 is turned on, driving power is supplied from the power source battery B to the entire system. The switch 13 is a release switch, and when the switch 13 is turned on, the image sensor 6 captures an image of the subject. The switch 14 is a compression rate change switch for changing the compression rate automatically set from information regarding data compression from the memory card 4 to a compression rate desired by the user, as will be described later.

In the following explanation, the compression rate is defined as the ratio (1/N) of the number of digital image data after compression to the number of original digital image data, and for example, a compression rate of 1/2 means that the number of digital image data is reduced by half. It means that. Therefore, the smaller the compression ratio, the more compressed the image data is. Further, a compression ratio of 1 is equivalent to no compression.

The imaging unit 2 includes a photographing lens 5 that forms an optical image of a subject A on a light-receiving surface of an image sensor 6, which will be described later, and the imaging unit that photoelectrically converts the light weight of the subject A and reads it out as an image signal (analog signal). element 6, an amplifier 7 for amplifying the image signal, an A/D converter 8 for converting the image signal into digital data, and storage of the digital image data and digital image data processed by the digital arithmetic processing section 3. It consists of an internal memory 9 that performs the following operations. The image sensor 6 is a single-plate solid-state image sensor having, for example, R (red), G (green), and B (blue) stripe filters, and is equipped with an electronic shutter function. Further, the internal memory 9 has at least one
In addition to the image area that can store photographed images, it has a work area for image processing by the digital arithmetic processing section 3, and also has a storage area for storing the results of the image processing.

The digital still image data stored in this storage area is output to the memory card 4 via the connector 15 in response to a control signal from the CPUI, and is stored in an image memory (not shown) of the memory card 4.

The digital arithmetic processing unit 3 performs color separation processing, white balance correction processing, and gamma (γ) processing on the digital image data.
) It is composed of an image processing circuit 10 that performs image processing such as correction processing and matrix processing, and a compression circuit 11 that performs data compression processing on digital image data that has undergone this image processing.

In the image processing circuit 10, R, G, and B image data are separated from the digital image data by a sampling circuit (not shown), and white balance correction (hereinafter referred to as WB correction) is performed on the R and B image data. and γ correction are performed. WB correction adjusts the signal levels of R and B image data so that when a reference white image illuminated with light of a set color temperature is taken, the R and B image data have the same signal level as the G image data. is modified by a predetermined color temperature coefficient. Furthermore, the γ correction performs data conversion by multiplying each R, G, and B image data that has been subjected to WB correction by a preset γ correction coefficient. Furthermore, a matrix circuit (not shown) generates a luminance signal (Y) and a color difference signal (R-Y, B-Y) from each R, G, and B image data that has been subjected to WB correction and γ correction processing. will be held. And the compression circuit 11
The luminance signal (Y) and color difference signal (R-Y
) and (B-Y), and the compressed digital image data is stored in a predetermined storage area of the internal memory 9 together with management data such as compression ratio.

As the compression circuit 11, for example, an ADCT compression circuit is used. This ADCT compression method is called ADCT (A
adaptive Discrete Co51n! Tr
The image data is converted into data in the frequency domain from low frequency to high frequency using an orthogonal transformation called (anform) transformation, and the number of sampling bits of high frequency component data is reduced to compress the number of data.

The reason for reducing the number of high-frequency component data is based on human visibility, which generally makes it difficult to see high-frequency components.

Said ADCT conversion 1tlso/JTCI/SC2/WG
This is a type of transform encoding based on the 8.N800 standard.

In this conversion encoding, the image data is divided into blocks of pixels (for example, 8 x 8 pixels) to divide the screen, and each block is converted into a two-dimensional DCT (D
This is performed by performing orthogonal transformation using the iscrete Co51ne Tranrform).

In this data conversion method, each converted term becomes more independent (more unrelated) than the original sample value, so redundant information is suppressed and encoding with good compression efficiency becomes possible.

The memory card 4 includes an SRAM that stores image data.
In addition to an image memory such as, a ROM 4a is included in which the storage capacity (information regarding data compression) of the image memory is stored in advance. Information on the storage capacity in this ROMJ a is
The memory card 4 is inserted into the camera body, and the connector 15
or when electrically connected via the memory card 4
If it is already attached to the camera body, when the main switch 12 is turned on, it is read out to the CPUI along with information other than image data, such as the remaining capacity of the memory and the type of memory card. In addition, R
Information on the storage capacity in OMJa is sent to the CPU via signal line 11.
It is read out by I. The CPU 1 calculates the compression ratio from the read storage capacity information. This compression ratio is then input to the compression circuit 11 via a signal line 12. The compression circuit 11 performs compression processing on digital image data based on a set compression rate. Note that the compression ratio may be calculated using a predetermined arithmetic expression, or may be calculated from a table in which compression ratios for storage capacities are stored in advance.

With the above configuration, when the photographer turns on the release switch 13, the optical image of the subject A formed by the photographing lens 5 on the light-receiving surface of the image sensor 6 is photoelectrically converted into an electric signal by the image sensor 6, and the image remains still. The image is captured as an image signal. After this image signal is amplified by the amplifier 7,
The signal is converted into a digital signal by the /D converter 8 and temporarily stored in the internal memory 9. The digital image data stored in the internal memory 9 is transferred to the image processing circuit 10 in the digital calculation unit 3, and the image processing circuit 10 performs color separation processing, γ correction processing, WB processing, and matrix processing. Luminance signal (Y) and color difference signal (R-Y, B-
Y) is generated. Furthermore, these luminance signals (Y) and color difference signals (R-Y.

B-Y) is data compressed by the ADCT compression method in the compression circuit 11 based on the compression rate input from the CPUI, and then temporarily stored in the internal memory 9 together with management data such as the compression rate. Then, the luminance signal (Y) and color difference signal (R-Y
, B-Y) is output from the internal memory 9 to the memory card 4 together with management data such as compression ratio, and stored in a predetermined storage area.

In the above shooting operation, when shooting with a compression rate different from the automatically preset compression rate, for example, when shooting with a lower compression rate of image data to prioritize image quality, or when shooting with a lower compression rate to prioritize the number of shots. When photographing with a higher compression ratio for the purpose of photographing, the photographer can change the compression ratio to the desired one by operating the compression change switch 14.

Note that this change in compression ratio also includes cases where compression is not performed. When the compression rate is changed by the compression change switch 14, the compression means 11 compresses the luminance signal (Y) and color difference signals (R-Y, B-Y) according to the changed compression rate. It is stored in the image memory in the memory card 4 together with the management data.

By the way, in the above embodiment, the digital image data of the luminance signal (Y) and the color difference signals (RY, B-Y) is compressed and stored in the memory card 4.
The 'digital image data outputted from the D converter 8 may be compressed by the compression circuit 11, and this compressed data may be stored in the memory card 4. In this case, the digital image data (compressed data) read out from the memory card 4 together with management data such as compression ratio during playback is
The data is expanded by an expansion circuit (not shown) at an expansion rate corresponding to the compression rate. The decompressed digital image data is then processed by the image processing circuit 10 to perform color separation processing, γ correction processing, WB processing, 7-trix processing, and N for TV display.
TSC encoding processing is performed.

Furthermore, without A/D conversion of the image data output from the image sensor 6, color separation processing and γ
Performs image processing including correction processing, WB processing, matrix processing, and NTSC encoding processing for TV display.
After A/D converting the NTSC signal that is the result of this processing,
The data may be stored in the memory card 4 after being subjected to compression processing.

Now, in the above embodiment, the memory card 4 is provided with a ROM 4a that stores information regarding data compression such as storage capacity, but instead of the ROM 4a, as shown in FIG. A switch 16 may be provided for setting.

In FIG. 2, the switch 16 is composed of four dip switches, and the dip switches 16 are designed to generate a 4-bit compression ratio signal. If the shaded side of each dip switch is set to the off state, and the output signal is "1" for the on state and rOJ for the off state, the output signal shown in the figure becomes ro 010J. For example, compression ratio 1/N
If the N value of ``0'' is expressed as a 4-bit signal,
010'' indicates a compression ratio of 1/2. Then, by using the switch 16, a compression rate of 16 (=2') can be set. Further, by assigning a predetermined compression rate corresponding to the 4-bit signal, it becomes possible to set an arbitrary compression rate.

〔Effect of the invention〕

As explained above, according to the present invention, information related to data compression such as compression rate and storage capacity is stored in advance in a removable memory card, and the compression rate of image data is set based on the information related to data compression. As a result, pixel data can be compressed and stored at a suitable compression rate depending on the memory capacity of the memory card. As a result, the memory card can be used effectively regardless of the memory capacity, and still video shooting can be easily enjoyed.

Furthermore, since the compression rate is automatically set when the memory card is installed or when the power is turned on if the memory card is already installed, the compression rate setting operation becomes unnecessary and the photographing operation becomes simple.

In addition, since a means for changing the compression rate is provided in the camera body, it is possible to avoid constraints on photography due to the preset compression rate by changing the preset compression rate to the desired compression rate as necessary. , it is possible to take pictures freely depending on the purpose of shooting, such as prioritizing image quality or number of shots.

In addition, since the memory card has a compression rate setting means,
A suitable compression ratio can be set according to the purpose of use of the memory card without impairing the versatility of the memory card.

[Brief explanation of drawings]

FIG. 1 is a system configuration diagram of a digital electronic still camera according to the present invention, and FIG. 2 is a front view of a memory card in which the compression ratio can be set. 1...CPU (system controller), 2...
Imaging unit, 3... Image processing unit, 4... Memory card,
5 photographing lens, 6...imaging element, 7... amplifier, 8
... A/D converter, 9... Internal memory, 10...
Image processing circuit, 11... Compression circuit, 12... Main switch, 13... Release switch, 14... Compression rate change switch, 15... Connector, 16... Compression rate setting switch.

Claims (1)

[Scope of Claims] 1. In a digital electronic still camera that converts an image signal captured by an imaging device into digital image data and stores the digital image data in a wearable storage device, the above-mentioned digital still camera has information regarding data compression. reading means for reading information regarding the data compression from the storage means;
A digital electronic still camera comprising: compression means for compressing digital image data; and compression ratio setting means for setting a compression ratio of the compression means based on read information regarding data compression. 2. The digital electronic still camera according to claim 1, wherein the camera body is provided with compression rate changing means for changing the compression rate set by the compression rate setting means. 3. The digital electronic still according to claim 1 or 2, wherein the reading means reads information regarding data compression from the storage means when the storage means is attached to the camera body. camera. 4. The digital electronic still camera according to claim 1, wherein the information regarding data compression is the storage capacity of the storage means. 5. The digital electronic still camera according to claim 1, wherein the information regarding data compression is a compression ratio. 6. The digital electronic still camera according to claim 5, wherein the storage means includes setting means for setting a compression ratio. 7. The digital electronic device according to claim 1, wherein information other than the image data stored in the storage means is read out when the power of the camera body is turned on. still camera.