JPH02105679A - Reproducing device and recorder for digital image - Google Patents

Abstract

PURPOSE:To easily and rapidly reproduce and display a simple image by providing an orthogonal transform means to output the DC component data of orthogonal transform coefficient and a display means to display the simple image, and reproducing the simple image by using the DC component data as it is. CONSTITUTION:A data compression circuit consists of an orthogonal transformation circuit 14 and an encoder circuit 15. Encoded compression data is stored in the image memory of a memory cartridge 30 via a connector 16. At this time, an AC component is stored separately from a DC component. The decoder circuit 17 of a digital still camera 109 decodes the DC component of one picture read out of the memory cartridge 30, and supplies it to a DC component memory 19. The DC component data accumulated in the DC component memory 19 is read out sequentially, and is converted to an analog signal by a D/A converter 20, then, it is displayed visually on a view finder 21 as a reduction simple image. In such a way, it is possible to easily display the composition and outline of a picture pattern or an image, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary of the Invention] Original image data is orthogonally transformed, and a simple image is displayed and reproduced using only the DC component data of the obtained orthogonal transform coefficients. In addition, only the AC component data of the orthogonal transform coefficients is encoded,
The DC component data is stored in a storage means without being encoded. By reading only the DC component data from the storage means, a simple display image can be easily obtained.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for reproducing a simple image from image data compressed by orthogonal transformation, and a device for recording compressed image data on a recording medium so that the simple image can be easily reproduced. .

Conventional technology and its problems Cameras equipped with solid-state electronic imaging devices such as CCDs and imaging tubes,
Since the amount of digital image data obtained from an optical scanning reader (OCR) is extremely large, the amount of data must be reduced by compressing the data when recording on a recording medium such as a semiconductor memory, magnetic recording medium, or optical disk. This is required. What are the typical methods of image data compression?

V, CHEN and V, PRATT″5cene
Adaptive Coder-IEEE Trans
, on Cows, Vol, C0N-32, NO
, 3, March 1984 pp 225-2 (2).

Divide the original image data into multiple blocks, orthogonally transform the original image data for each block to obtain a transformation coefficient, normalize this transformation coefficient by dividing it by an appropriate normalization coefficient, and round off the fraction. Compressed data is obtained by quantizing and encoding this quantized value.

The above-mentioned orthogonal transform encoding method has the advantage of good compression efficiency. However, this compressed data cannot be used as is for playback and display; decoding and inverse conversion processing are required for playback and display, which requires a huge amount of calculation.

On the other hand, there are cases where it is desired to reproduce and confirm an image after data compression or an image recorded on a recording medium, even if it is a simple image. For example, this is the case when images taken with digital still cameras, which have been in the spotlight in recent years, are immediately viewed using a vinyl viewfinder or the like. This image reproduction display does not need to be of high quality; it is sufficient to confirm the image pattern or to know the outline of the image.

Summary of the Invention Purpose of the Invention The present invention provides a digital image reproducing device that can relatively easily reproduce simple images as described above, and a digital image reproducing device that records compressed data so that the simple images can be reproduced relatively easily. The purpose is to provide an image recording device.

Structure and effects of the invention A digital image reproducing device according to a first invention is as follows.

Orthogonal transformation means that orthogonally transforms one screen's worth of original image data and outputs DC component data of the obtained orthogonal transformation coefficients, and a display that displays a simplified image expressed by the DC component data output from the orthogonal transformation means. It is characterized by having the means.

According to the first invention, a simple image is reproduced by directly using only the DC component data of orthogonal transform coefficients obtained by orthogonal transform processing. Therefore, the simple image can be reproduced and displayed relatively easily and quickly.

A digital image reproducing device according to a second invention.

The digital image reproducing device of the first invention further includes an encoding means for assigning and encoding a predetermined code to each of the DC component data and the AC component data of the orthogonal transform coefficients output from the orthogonal transform means; A storage medium for storing data encoded by the encoding means, and the encoded data of the DC component stored in the storage medium are read.

It is characterized by comprising a decoding means for decoding and providing it to the display means.

According to the second invention, there is provided an encoding means for encoding the DC component and AC component of the orthogonal transform coefficient and providing it to the storage medium, and a decoding means for decoding the encoded DC component. Therefore, it is possible to store all compressed image data in the storage medium, and by reading and decoding only the DC component stored in the storage medium, it is possible to create a simple image based on the DC component relatively easily. be able to.

In other words, it is possible to relatively easily reproduce and display a simple image from the image data stored in the storage medium.

In a third aspect of the invention, the apparatus according to the second aspect further includes switching means for switching either the output data of the orthogonal transformation means or the output data of the decoding means in accordance with a switching signal and providing the same to the display means. It is characterized by having

Therefore, according to the third invention, it becomes possible to selectively reproduce and display either the data before being stored on the storage medium or the data after being stored.

A fourth invention provides the apparatus of the first invention further including encoding means for encoding AC component data of the orthogonal transform coefficients output from the orthogonal transform means, and DC component data of the orthogonal transform coefficients output from the orthogonal transform means. It is characterized by comprising a storage means for storing component data and encoded AC component data outputted from the encoding means.

In the fourth invention, only AC component data of orthogonal transform coefficients are encoded. Therefore, since the DC component data is not encoded, it can be reproduced and displayed simply by reading it from the storage means.

A fifth invention provides the apparatus according to the fourth invention, further comprising switching either one of the DC component of the orthogonal transformation coefficient output from the orthogonal transformation means and the DC component read from the storage means in accordance with a switching signal. The present invention is characterized in that a switching means is provided to provide the display means.

Also in the fifth invention, as in the third invention, either the data before storage or the data after storage can be selectively reproduced and displayed in the storage means.

A digital image recording device according to a sixth invention.

It is characterized by comprising orthogonal transformation means for orthogonally transforming original image data for one screen and outputting DC component data of the obtained orthogonal transformation coefficients, and storage means for storing output data of the orthogonal transformation means. .

A seventh aspect of the present invention is characterized in that the apparatus of the sixth aspect is further provided with encoding means for assigning and encoding a predetermined code to the AC component data of the orthogonal transform coefficients obtained by the orthogonal transform means. This encoded AC component data is stored in the storage means together with the DC component data.

In this way, the 6th. According to the seventh invention, since the AC component of the orthogonal transform coefficient is stored in the storage means without being encoded,
There is no need to decode the DC component when reading it from the storage means and using it. This allows simple images to be reproduced and displayed relatively easily and quickly using only the DC component.

A digital image reproducing device according to an eighth invention.

The present invention is characterized by comprising display means for reading the DC component of the orthogonal transformation coefficients stored in the storage means and displaying a simplified image represented by the DC component data.

According to the eighth aspect of the invention, since the display means for reading out the unencoded DC components of the orthogonal transform coefficients and displaying the simplified image is provided, the simplified image can be reproduced relatively easily and quickly.

According to a ninth aspect of the present invention, the first or eighth device is provided with interpolation means that performs interpolation processing on the DC component data and provides the data to the display means.

According to the ninth invention, a smooth display image can be obtained by interpolation processing.

DESCRIPTION OF THE EMBODIMENTS FIG. 1 shows an example of the electrical configuration of a digital still φ camera IO, and a memory cartridge 30 is also shown.

The memory cartridge 30 has a built-in semiconductor memory, and the concept includes what is called a memory card and an IC card. The memory cartridge 30 is removably attached to the digital still camera IO.
Connector 1B connects the digital
It is electrically connected to the still camera lO. Connector 1
6 includes a terminal on the cartridge 30 side and a terminal provided on the camera 10.

The memory cartridge 30 is equipped with an image memory that stores compressed digital image data provided from the digital still φ camera IO, as will be described later.

Photographing processing, data compression processing, transfer processing of compressed image data to memory cartridge 30, and other processing in the digital still camera IO are controlled by a system controller (path shown). system·
The controller is a CPU.

It consists of a ROM that stores the execution program, a RAM that stores necessary data, and the like.

The subject image passes through the optical system 11 and is formed on the image sensor 12, and the image sensor 12 outputs a video signal. This video signal is then subjected to necessary signal processing such as amplification, exposure adjustment and single color adjustment in a signal processing circuit (not shown), and then converted into a digital signal in an A/D conversion circuit 13. This digital signal is further supplied to the orthogonal transform circuit 14 and subjected to orthogonal transform processing.

The concept of orthogonal transformation processing is as follows.

The captured original image data for one screen is composed of NXM pixels, and one pixel is represented by, for example, 8-bit data. Such original image data is divided into a plurality of blocks in the vertical and horizontal directions of the screen. One block is composed of, for example, 8×8 pixels.

The original image data is processed by DCT (Dlscr) for each block.
ete Co51ne Transror*at1on
) transform (a type of orthogonal transform), and its DCT coefficients are determined. DCT coefficients are stored in a coefficient memory (path shown) for each block. When the DCT processing is completed for all the original image data for one screen, normalization processing is performed next. In the normalization process, DCT coefficients are read from the memory block by block, and these coefficients are divided by an appropriate normalization coefficient. The fraction of this division result is rounded off and quantized. Generally, threshold processing is performed simultaneously with or before this normalization processing. Threshold processing is a process of subtracting a certain threshold value from the DCT coefficient. For DCT coefficients smaller than this threshold, the subtraction result is set to 0. The lowest order (low frequency) component of each block (
No threshold processing is performed on the DC component (which represents the average brightness of each block). Further, the DC component is generally normalized using a different normalization coefficient from other components (this is called an AC component) in normalization processing.

The DC component of the DCT coefficient obtained by orthogonally transforming the image data for one screen in this way is transferred to the switching circuit 1.
8 is applied to one input terminal of the 8.

Further, the DC component and AC component of the DCT coefficient are supplied to the encoding circuit 15 and encoded. Examples of encoding include Huffman encoding and run-length encoding. Usually D
Simultaneously with or before CT processing, normalization or encoding, the two-dimensional array of image data is zigzag-scanned.
Converted to dimensional array data. The orthogonal transform circuit 14 and the encoding circuit 15 constitute a data compression circuit. Part or all of the data compression processing described above can of course be executed by software processing by the CPU.

The encoded compressed data is sent to the memory via the connector 16.
The image is stored in the image memory of the cartridge 30. At this time, it is preferable to store the AC component and the DC component separately. Due to this.

Only the DC component can be easily read out from the image memory.

The digital still camera IO is equipped with a decoding circuit 17. The decoding circuit 17 is a memory cartridge 30
This is to decode one screen worth of DC components read from. The decoded DC component is applied to the other input terminal of the switching circuit 18.

The switching circuit 18 supplies one of the DC component data input to the two input terminals to the DC component memory 19 in response to a switching signal. The switching signal is created by the system controller in response to an input from a selection switch provided on the operating section (not shown) of the digital still camera 10.

The DC component data stored in the DC component memory 19 is sequentially read out and converted into an analog signal by the D/A converter 20, and then visually displayed on the viewfinder 21 as a reduced simplified image. The viewfinder 21 is composed of, for example, a liquid crystal display device.

Since a simple image based on DC component data is displayed, the number of pixels may be small.

Since the DC component represents the average brightness of each block,
Even if the image is composed only of DC components, it is possible to see the entire image pattern on one screen. In this way, a simplified image of the image captured by the imaging optical system of the camera IO or stored in the memory cartridge 30j is displayed. This makes it possible to easily display the composition, outline, etc. of two-picture patterns or images. This display can also be used to confirm when erasing image data in the memory cartridge.

Particularly in this embodiment, since the switching circuit 18 is provided, the output side of the orthogonal transformation circuit 14 is connected to the DC component memory 19.
This makes it possible to immediately display the captured image on the second viewfinder without having to store it in a memory cartridge. It is also possible to sequentially display images captured by the imaging optical system before imaging, and it is also possible to achieve the exact function of the viewfinder 21.

In this embodiment, both the DC and AC components are encoded in the circuit 15 and then transferred to the memory cartridge 30 and stored in the image memory, but the DC component is stored in the memory cartridge 30 without being encoded. It's okay. In this case, the decoding circuit 17 becomes unnecessary.

Furthermore, if the DC component data is interpolated and displayed on the viewfinder, it can be displayed on a display device having more pixels than the DC component, and the displayed image will also be smooth.

FIG. 2 is a block diagram showing another embodiment.

In this figure, the same components as those shown in FIG. 1 are designated by the same reference numerals, and their explanation will be omitted.

Of the DCT coefficient data orthogonally transformed by the orthogonal transform circuit 14, the AC component is encoded by the encoding circuit 15 and transferred to the memory card cartridge 30 via the connector 1G, and the DC component is input to the encoding circuit 15. is transferred to the memory cartridge 30 via the connector 16 without being encoded. and,
These AC and DC components are stored in separate areas within the image memory.

When reproducing and displaying a reduced simplified image from orthogonally transformed DC component data, the system controller of the camera IO reads only the DC component of the image data recorded in the memory cartridge 30 and temporarily stores it in the DC component memory 19. Sdoor. As a result, only the DC component data is D/
After being subjected to A conversion processing, it is displayed on the viewfinder 21.

The DC component of the orthogonally transformed signal is stored in the memory cartridge 3 without being encoded.
Since it is stored as 0, it is possible to create a simple playback image relatively easily.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the invention. FIG. 2 is a block diagram showing another embodiment. lO...Digital still camera. 14...Orthogonal transformation circuit. 15... Encoding circuit. ”7...Decoding circuit. 18...Switching circuit. 21...Viewfinder. 30...Memory Φ cartridge. Below Up

Claims (9)

[Claims] (1) Orthogonal transformation means for orthogonally transforming one screen's worth of original image data and outputting DC component data of the obtained orthogonal transformation coefficients, and a simplified image expressed by the DC component data output from the orthogonal transformation means. A digital image reproducing device comprising display means for displaying images. (2) Encoding means that assigns and codes predetermined codes to each of the DC component data and AC component data of the orthogonal transformation coefficients output from the orthogonal transformation means, and stores the data encoded by the encoding means. The digital image reproducing apparatus according to claim 1, further comprising: a storage medium for storing data, and a decoding means for reading and decoding the encoded data of the DC component stored in the storage medium, and providing the encoded data to the display means. . (3) The apparatus according to claim (2), further comprising a switching means that switches either the output data of the orthogonal transformation means or the output data of the decoding means to the display means in accordance with a switching signal. Digital image reproduction device. (4) Encoding means for encoding the AC component data of the orthogonal transform coefficients output from the orthogonal transform means, and the DC component data of the orthogonal transform coefficients output from the orthogonal transform means and the data output from the encoding means. The digital image reproducing apparatus according to claim 1, further comprising a storage means for storing encoded AC component data. (5) Switching means for switching either the DC component of the orthogonal transformation coefficient outputted from the orthogonal transformation means or the DC component read from the storage means in accordance with a switching signal and providing it to the display means. The digital image reproducing device according to claim (4). (6) A digital device comprising orthogonal transformation means for orthogonally transforming original image data for one screen and outputting DC component data of the obtained orthogonal transformation coefficients, and storage means for storing output data of the orthogonal transformation means. Image recording device. (7) Further comprising encoding means for assigning and encoding a predetermined code to the AC component data of the orthogonal transform coefficients obtained by the orthogonal transform means, and the encoded AC component data is stored in the above-mentioned storage together with the DC component data. A digital image recording device according to claim 6, wherein the digital image recording device is stored in a means. (8) A digital image reproducing device comprising: display means for reading the DC component of orthogonal transformation coefficients stored in the storage means and displaying a simplified image represented by the DC component data. (9) The digital image reproducing apparatus according to claim (1) or (8), further comprising interpolation means that applies interpolation processing to the DC component data and provides the resultant data to the display means.