JP3062702B2 - Image storage device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image storage device in a digital still video camera having a data compression function by orthogonal transformation, and more particularly to an image storage device suitable for multi-screen display.

[0002]

2. Description of the Related Art Recently, as a still video camera, CC
An analog image signal captured by an image sensor such as D
A digital still video camera has been proposed in which a digital image signal is converted into a digital image signal by a converter and recorded in a storage device such as a semiconductor memory (Japanese Patent Application Laid-Open No. 63-72283).
Reference).

In such a digital still video camera, image data is compressed in consideration of the capacity of a storage device so as to save storage capacity. One of such data compression techniques is orthogonal transform coding. It has been known. In orthogonal transform coding, the entire image represented by digital image data obtained by imaging is divided into a plurality of blocks,
For each block, orthogonal transform is performed using, for example, a discrete cosine transform (DCT), and the obtained frequency information (referred to as a transform coefficient) is quantized and coded to perform data compression and recording in a storage device. I do.

A recording / reproducing system in a digital still video camera having such an image data compression function generally has a configuration as shown in FIG.
That is, at the time of recording, an optical image of a subject is formed on an image sensor 1 such as a CCD via an optical system (not shown). This optical image is subjected to photoelectric conversion and analog signal processing such as color separation in the process circuit 2, then converted to a digital signal by the A / D converter 3, and converted to a field memory 4 having a storage capacity for one screen. To temporarily memorize. The stored data is compressed by the above-described orthogonal transform coding in the data compression circuit 5 and recorded in the memory 6. 1 in memory 6
It is recorded sequentially in screen units.

At the time of reproduction, data is taken out from the memory 6 for each screen, decompressed by the decompression circuit 7 and returned to the original image data, then temporarily stored in the field memory 8 and stored in the D / D memory.
The signal is converted into an analog signal by the A converter 9 and then converted into R, G, and B signals via the matrix circuit 10. Each operation timing at the time of recording / reproduction is controlled by a tamping signal from the system controller 11.

[0006]

If, for example, it is desired to know what kind of image data is stored in the memory as soon as possible, a multi-screen display for displaying a plurality of images simultaneously in one screen is indexed. It is convenient to display the images stored in the memory at the same time on one screen.

[0007] However, in the conventional still video camera having the data compression function shown in FIG. 7, the reproduction process is performed one image at a time.
The hardware configuration shown in (1) had to be adopted. That is, data for one screen is taken out from the memory 6, expanded by the expansion circuit 7, and stored in the field memory 8. Up to this point, the processing is the same as the normal reproduction processing. However, after that, a sampling point extraction circuit 12 is provided, and sampling points are extracted according to the number of images displayed on one screen. The image is stored in the multi-screen memory 13 as a screen. The above operation is repeated for the number of images to be displayed on one screen. For example, in the case of multi-screen display in which one screen is divided into four and four images are simultaneously displayed, the operation until the image is stored in the multi-screen memory 13 is repeated four times. Thereafter, the multi-image data stored in the multi-screen memory 13 is converted into an analog signal by the D / A converter 9, and the same processing as in the normal reproduction is performed.

As described above, conventionally, in order to perform multi-screen display, it is necessary to newly add the sampling point extracting circuit 12, the multi-screen memory 13, and the like. In addition, since the same reproduction processing is repeated, processing for multi-screen display takes time. The present invention has been made in view of the above circumstances, and provides an image storage device that does not require changing the hardware configuration of a camera when performing multi-screen display, and that can simplify playback processing. With the goal.

[0009]

SUMMARY OF THE INVENTION Accordingly, the present invention digitizes captured image data, divides the digital image data into a plurality of blocks, and performs orthogonal transformation for each block to compress the data. In an image storage device of a digital still video camera having a data compression function, a storage area for image data is stored in a low-frequency component storage area for storing low-frequency component data after orthogonal transform, and a high-frequency component data after orthogonal transform is stored. Control means for dividing and storing image data after orthogonal transformation in each of the storage areas while dividing the image data into low-frequency components.
The storage capacity of the minute storage area is equivalent to one screen.
Was.

[0010]

[0011]

In such a configuration, the taken image data is subjected to orthogonal transformation and then separated by the control means into low frequency component data and high frequency component data. The low frequency component data is stored in the low frequency component storage area of the image storage device. And the high frequency component data is stored in the high frequency component storage area.

As described above, by dividing the compressed data of each image into low-frequency component data and high-frequency component data and storing the divided data, each image stored in the low-frequency component storage area during multi-screen display is displayed. The multi-screen display can be performed only by reading and processing only the low-frequency component data for one screen at a time. In addition, if the low-frequency component storage area has a capacity corresponding to one screen and the low-frequency component data of all the images stored in the image storage device is stored, all the contents in the image storage device can be stored in one screen.
Images can be displayed on multiple screens.

[0013]

An embodiment of the present invention will be described below with reference to the drawings. Note that the same components as those in the related art are denoted by the same reference numerals, and description thereof is omitted. In FIG. 1 showing the configuration of the present embodiment, a memory 20 as an image storage device of the present embodiment includes a low frequency component storage area 20A for storing low frequency component data of compressed data of each image after orthogonal transformation, and a high frequency component storage area 20A. It is divided into a high-frequency component storage area 20B for storing component data.
Note that the storage capacity required for the same number of recordings is the same as the conventional one.

The data orthogonally transformed and compressed by the compression circuit 5 is separated into low-frequency component data and high-frequency component data by a system controller 11 as control means. Storage area 20
A, and the high frequency component data is written to the high frequency component storage area 20B. Next, a data storage operation in this embodiment will be described.

For example, assume that the memory 20 stores N images. In this case, as shown in FIG. 2, the storage area of the memory 20, No. 1 image memory area 20 _{1, respectively, ...,}
N-th image memory area 20 _n, divides _..., into N to the N-th image memory area 20 _N. Further, each image memory area is divided into N blocks. In this state, each frequency component data of each image obtained by compression is divided into N, and data from the low frequency side to 1 / N is sequentially stored in the _first image memory area 201 for each image. The remaining (N-1) /
The data of N is sequentially stored in the image memory areas subsequent to the _second image memory area 202. Accordingly, since all of the low-frequency component side data of the 1 / N of the N images is to be stored in No. 1 image memory area 20 _1, in this case, No. 1 image memory area 20 ₁ is low corresponds to the frequency component storage area 20A, so that the up No.2 image memory area 20 ₂ to N-th-th image memory area 20 _N corresponds to a high-frequency component storage area 20B.

For example, the case where the n-th image is stored in the memory 20 will be described. As shown in the flowchart of FIG.
It is digitized by the conversion circuit 3 and stored in the field memory 4 (S1).
CT conversion is performed (S2). Next, the write from the low-frequency component side of the data compressed by the DCT transform data components up 1 / N the first number n th block of the image memory area 20 ₁ (S3), the remaining (N-1) / N is the (n-1) of the latter half of the n-th image memory area _20n.
Write over the block and the (N-n) block in the first half of the (n + 1) th image memory area 20 _{n + 1} (S
4).

In this manner, the low-frequency component data and the high-frequency component data are sequentially stored in the memory 20 from the first image to the Nth image. According to such a configuration, when performing multi-screen display, as shown in the flowchart of FIG. 4 extracts only the low-frequency component data that is stored in No. 1 image memory area 201 (S11), expanding circuit 7, the DCT is inversely transformed and stored in the field memory 8 (S12). The stored image data is stored in a D / A
The converter 9 converts the signal into an analog signal (S13), and takes out the image as an image output, which is the same as the conventional normal image reproduction processing, whereby N multi-images can be displayed on one screen.

FIG. 5 shows an example in which a multi-screen display of four screens is used. That is, the first image memory area
The 20 ₁ stores the data from the low frequency side to 1/4 of the image data up to 4 th first sheet. The remaining 3/4 high frequency data of each image is stored in the second image memory area 20
Sequentially stores so that no gap ₂ to No. 4 image memory area 20 _4.

When only the n-th image is reproduced normally, as shown in the flowchart of FIG. 6, data of the n-th block in the _first image memory area 201 (low-frequency component data LDCT ) reads (S21), then the second half portion of the n-th image memory area 20 _n (n-1) blocks and the (n + 1) th image memory area 20 _{n + 1} of the first half of the (n-n) The data (high-frequency component data HDCT) written over the blocks is read (S2
2). Then, DCT inverse transform is performed on each of these data, temporarily stored in a field memory (S23), and D / A converted (S24) to obtain an image output.

As described above, if the data compressed by the orthogonal transformation is divided into low-frequency component data and high-frequency component data and recorded in the memory, the multi-screen display can be performed.
Processing can be performed in the same manner as normal reproduction processing, and there is no need to add a new hardware configuration. Further, image data necessary for multi-screen display can be read at once without repeating the same processing as the number of multi-images, and the processing time can be reduced.

In the case of a multi-screen used for an index or the like, it is sufficient to know what image is stored in the memory, and a clear image is not required. Therefore, data containing only low-frequency components is sufficient. Absent.

[0022]

According to the present invention as described in the foregoing, when storing the image data by performing data compression by the orthogonal transformation coding, with stores divided low frequency component data and the high frequency component data, low Storage area for frequency component data
Since the storage capacity is equivalent to one screen, even when multi-screen display is performed, it can be performed in the same manner as in normal reproduction processing, and there is no need to change the hardware configuration. Further, the processing time in multi-screen display can be reduced. And one screen
Allows multi-screen display of all images in the image storage device
become.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a still video camera to which an embodiment of the present invention has been applied.

FIG. 2 is a schematic diagram of a memory configuration of the embodiment.

FIG. 3 is a flowchart illustrating a data write operation of the embodiment.

FIG. 4 is a flowchart illustrating a multi-screen display operation of the embodiment.

FIG. 5 is a diagram illustrating an example of a memory configuration when performing multi-screen display of four screens;

FIG. 6 is a flowchart illustrating a normal playback operation of the still video camera to which the embodiment is applied;

FIG. 7 is a configuration diagram showing a general recording / reproducing system of a still video camera having a data compression function.

FIG. 8 is a configuration diagram showing a conventional reproduction system for multi-screen display.

[Explanation of symbols]

1 imaging device 3 A / D
Converter 4,8 Field memory 5 Compression circuit 7 Expansion circuit 9 D / A
Converter 11 System controller 20 Memory 20A Low frequency component storage area 20B High frequency component storage area

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yuki Sakai 2970, Ishikawa-cho, Hachioji-shi, Tokyo Inside Konica Corporation (56) References JP-A-4-971 (JP, A) (58) Fields investigated ( Int.Cl. ⁷ , DB name) G06F 3/14 350 G06T 9/00 H04N 1 / 41,5 / 92,9 / 79

Claims (1)

(57) [Claims] A digital still video camera having a data compression function of digitizing captured image data, dividing the digital image data into a plurality of blocks, and performing orthogonal transformation for each block to compress the data. In the image storage device, the storage area of the image data is
A low-frequency component storage area for storing low-frequency component data after orthogonal transformation, and a high-frequency component storage area for storing high-frequency component data after orthogonal transformation, and the image data after orthogonal transformation is stored in each of the storage areas. Control means for performing separate storage , wherein the storage capacity of the low-frequency component storage area is divided by one screen.
Image storage device, characterized in that the person.