JPH04237281A - Picture processing unit - Google Patents

Abstract

PURPOSE:To allow the user to set optionally picture quality of a storage object in a digital still video camera utilizing the variable length coding system. CONSTITUTION:A camera 1 applies photoelectric conversion to a picture to obtain an analog picture signal and it is converted into a digital picture signal and coded into a set compression rate by a code quantity adjustment dial 3. The coded digital picture signal is decoded by a decoding section 6 and displayed on a display device 7 together with the compression rate. While the picture displayed on the display device 7 is observed, the compression rate is revised as required. When the compression rate is decided, the digital picture signal coded by the compression rate is stored in a storage section 8.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus, and more particularly, to an image processing apparatus that compresses and stores images captured by an electronic still camera or the like.

0002

[Prior Art] One of the techniques for highly efficient compression encoding of natural images is a method that combines orthogonal transformation with variable length encoding, and it is being adopted as an international standard for color natural image encoding methods. be. In such a coding method, by controlling specific parameters, it is possible to control the image quality of a decoded image and the amount of code in decoding. Note that the difference between the amount of code and image quality is that the larger the amount of code, that is, the lower the degree of compression, the smaller the deterioration of the image quality from the original image; conversely, the smaller the amount of code, that is, the lower the degree of compression. There is a relationship such that the larger the value, the greater the deterioration in image quality from the original image.

0003

[Problem to be solved by the invention] However, during encoding, adaptive processing is performed using local correlation of images, so highly efficient compression is possible according to the characteristics of the processed image. On the other hand, the relationship between the code amount control parameter and the obtained code amount differs for each processed image. Therefore, even if encoding is performed using the same code amount control parameter, an image with a detailed pattern will generally have a large amount of code, and a flat image with many solid areas will have a small amount of code.

[0004] Therefore, when such a compression encoding technique is applied to, for example, a digital still camera, there is a problem that the number of images that can be recorded on one recording medium is usually not uniquely determined. To avoid this, in order to control the amount of code per image to be constant, for example, the encoding is
A method has been proposed in which data for controlling the code amount is calculated using one bus memory, and the code amount is controlled using two bus memories.

However, this method of controlling the amount of code per image to be constant has the problem that the image quality is not constant because the amount of code is constant for each image. Furthermore, the user cannot arbitrarily select the image quality. Another problem is that real-time processing is often difficult.

By the way, in such an electronic still video camera that digitally compresses and encodes an image signal output from an image sensor and records it on a recording medium, it is difficult for general users to freely control the image quality of the object to be photographed. Whether settings can be made is considered to be extremely important information for photographing. An object of the present invention is to enable a user to arbitrarily set the image quality of a storage target in a digital still video camera using such a variable length encoding method.

[0007]

[Means for Solving the Problems] The invention as set forth in claim 1 provides an imaging means for photoelectrically converting an image to obtain an analog image signal, and a conversion means for converting the analog image signal obtained by the imaging means into a digital image signal. a compression rate setting means for setting a compression rate of the digital image signal converted by the conversion means; and an encoding means for encoding the digital image signal at the compression rate set by the compression rate setting means;
The image processing apparatus is provided with a storage means for storing the digital image signal encoded by the encoding means.

In the invention according to claim 2, there is provided an imaging means for photoelectrically converting an image to obtain an analog image signal; a conversion means for converting the analog image signal obtained by the imaging means into a digital image signal; a compression rate setting means for setting a compression rate of the converted digital image signal; an encoding means for encoding the digital image signal at the compression rate set by the compression rate setting means; and an encoding means for encoding the digital image signal with the compression rate set by the compression rate setting means. a storage means for storing the digital image signal encoded by the encoder; a decoding means for decoding the digital image signal encoded by the encoding means; and an image display means for displaying the image decoded by the decoding means. is provided in the image processing device.

According to the third aspect of the invention, the image processing apparatus according to the first or second aspect is provided with a compression rate display means for displaying the compression rate set by the compression rate setting means. According to the fourth aspect of the present invention, in the image processing apparatus according to the second and third aspects, the image obtained by the imaging means is displayed on the image display means in real time.

0010

In the image processing apparatus according to the first aspect, an image is photoelectrically converted by the imaging means to obtain an analog image signal. This is converted into a digital image signal, encoded at the compression rate set by the compression rate setting means, and the encoded digital image signal is stored in the storage means. The invention according to claim 2 decodes the encoded digital image signal and displays it on the display means, the invention according to claim 3 displays the compression rate set by the compression rate setting means, and the invention according to claim 4 In the invention, images obtained by the imaging means are displayed on the image display means in real time.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the image processing apparatus of the present invention will be described in detail below with reference to FIGS. 1 and 2. In FIG. 1, 1 is a camera as an imaging means, and camera 1 is C
It is composed of solid-state elements such as CDs (Charge Coupled Devices). This camera 1 is controlled by a drive section (not shown), and is configured to photoelectrically convert an image of a subject and output an analog image signal.
2 is an A/D as a conversion means for converting the analog image signal output from the camera 1 into a digital image signal.
This is the conversion section.

Reference numeral 3 denotes a code amount adjustment dial as compression rate setting means for setting the compression rate to an arbitrary value. Reference numeral 4 denotes an image compression encoding unit as an encoding means that performs encoding based on the compression rate adjustment parameter value. The compression encoding method in the image compression encoding unit 4 adopts the ADCT method, and the compression method using the compression amount adjustment parameter includes, for example, compression by dividing or multiplying the quantization matrix by the compression amount adjustment parameter. This can be done in various ways, such as by varying the amount. The image data encoded by the image compression encoding unit 4 is supplied to a compression rate calculation unit 5 that calculates a compression rate, and a decoding unit 6 that serves as a decoding means that performs decoding. .

Reference numeral 7 denotes a display device, which displays the image compressed and encoded by the image compression encoder 4 and decoded again by the decoder 6, and also displays the image compressed and encoded by the image compression encoder 4. The calculated compression ratio is displayed. For example, in the case of an electronic still camera, a liquid crystal display (LCD) is often used as the display device 7, but any other type may be used. Reference numeral 8 denotes a storage unit as a storage means, which is constituted by an electrical storage medium such as a semiconductor memory, an IC card, or a magnetic disk. The storage unit 8 stores data encoded by the image compression encoding unit 4 and information used to compress the image data, such as code amount adjustment parameters.

Next, the operation of the image processing apparatus configured as described above will be explained. An image of a subject (not shown) is photoelectrically converted by a camera 1, and an analog image signal is supplied to an A/D converter 2. The analog image signal supplied to the A/D converter 2 is converted into a digital image signal, temporarily stored, and then supplied to the image compression encoder 4. The image compression encoding section 3 compresses and encodes the digital image signal supplied from the A/D conversion section 2 based on the compression rate adjustment parameter value supplied from the code amount adjustment dial 4.

The image data whose total data amount has been reduced by being encoded by the image compression encoding section 3 is displayed on the display device 7 after the compression rate is calculated as a percentage of the original code amount by the compression rate calculation section 5. Ru. Also, the compressed data is stored in the decoding unit 6.
The data is decoded, reproduced, and displayed on the display device 7. This display of the compression ratio and the decoded image is displayed while the camera 1 is photographing the subject or during the compression ratio setting mode, and the photographer can check the image quality of the image displayed on the display device 7. and turn the code amount adjustment dial 3 to obtain the desired image quality.
can be adjusted, and the adjusted image is displayed on the display device 7.

When the photographer determines the compression rate while looking at the display device 7, the encoded data decoded and displayed on the display device 7 at that time is supplied to the storage section 8 and stored therein. At this time, information used to compress the image data is also stored.

In the embodiment described above, the compression ratio is displayed on the display device 7, but it may be displayed separately from the image decoded by the decoding unit 6 and displayed. You can also do this without displaying it by marking the code amount adjustment dial with, for example, "High quality,""Normal," or "High compression," and compressing based on the pre-calculated compression amount adjustment parameter. It is possible.

In another embodiment of the invention, the display device 7 can be a viewfinder of a camera. As shown in FIG. 2, the viewfinder is installed so that the photographer can constantly monitor the image in the field of view that he or she wishes to photograph. In this embodiment, the viewfinder is an electronic display means such as a small CRT. When controlling images with the code amount adjustment dial, inputting images from the camera, A/
If D conversion, encoding, decoding, and display are all processed in real time, the photographer can constantly see changes in the image while making corrections using the code amount adjustment dial, making it extremely easy to adjust the image quality. become. Furthermore, at this time, the compression ratio as described above can also be displayed in real time in the viewfinder.

[0019]

According to the present invention, since the user can arbitrarily set the image quality of the object, it is possible to store an image with a quality that suits the user's purpose. Furthermore, the number of memory sheets (capacity) can also be adjusted.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of an image processing apparatus of the present invention.

FIG. 2 is an external view of an electronic still camera.

[Explanation of symbols]

1 Camera 2 A/D conversion section 3 Code amount adjustment dial 4 Image compression encoding unit 6 Composite section 7 Display device 8 Memory section

Claims (4)

[Claims] 1. Imaging means for photoelectrically converting an image to obtain an analog image signal; converting means for converting the analog image signal obtained by the imaging means into a digital image signal;
compression rate setting means for setting the compression rate of the digital image signal converted by the conversion means; encoding means for encoding the digital image signal at the compression rate set by the compression rate setting means; 1. An image processing apparatus comprising: storage means for storing a digital image signal encoded by the means. 2. Imaging means for photoelectrically converting an image to obtain an analog image signal; converting means for converting the analog image signal obtained by the imaging means into a digital image signal;
compression rate setting means for setting the compression rate of the digital image signal converted by the conversion means; encoding means for encoding the digital image signal at the compression rate set by the compression rate setting means; storage means for storing the digital image signal encoded by the means; decoding means for decoding the digital image signal encoded by the encoding means; and displaying the image decoded by the decoding means. An image processing device comprising an image display means. 3. The image processing apparatus according to claim 1, further comprising compression rate display means for displaying the compression rate set by the compression rate setting means. 4. The image processing apparatus according to claim 2, wherein the image obtained by the imaging means is displayed on the image display means in real time.