JPH04151975A - Digital electronic still camera - Google Patents

Abstract

PURPOSE:To execute efficient compression recording by identifying a natural picture forming a multi-gradation and a character picture forming binary gradation from a picture of an object and compressing each picture in response to the identified characteristic. CONSTITUTION:A picture signal grasped via an image pickup lens 1 and an aperture 2 is subjected to conversion processing into a luminance signal and a chrominance signal at a processing circuit 3. Its output signal 4 is given to an A/D converter 5, from which a digital data 6 is obtained and stored in a frame memory 7 for each frame. The frame data 8 outputted from the memory 7 is inputted to a picture identification circuit 9, in which the data is identified into a character picture (binary picture) and a natural picture (multi-value picture). The identified natural picture data 11 and character picture data 10 are compressed respectively by compression circuits 15, 12 by the DCT and MH system and the compressed data 16, 13 are recorded on a recording medium 14.

Description

Detailed Description of the Invention (Means for Solving the Problems) In order to achieve the object of the present invention, in an electronic still camera that electronically photographs still images, natural images and binary images such as characters are combined. The present invention includes an identification means for automatically identifying the image, and a compression recording method switching means for automatically switching the compression recording method of the image data according to the image identified by the identification means.

(Embodiment) The figure is a functional block diagram showing an embodiment of the present invention. 1 is an imaging lens of an electronic still camera, 2 is an aperture, 3 is a processing circuit that generates a luminance signal and a color difference signal from the image signals captured by the imaging lens 1 and the aperture 2, and 5 is a processing circuit 3
It is an analog-to-digital converter that is connected to an analog to digital converter and converts its output 4 into a digital signal. 7 is a frame memory that stores the digital image output 6 converted by the analog-to-digital converter 5 for each screen, and 9 is a character that uses the output 8 of the frame memory as frame data and that frame data constitutes a binary image. Image identification circuit for identifying whether it is an image or a natural image constituting a multi-valued image (multi-gradation image), 1
2 is an MI (method) compression circuit that compresses the character image output 10 whose frame data has been identified as a character image constituting a binary image by the image identification circuit 9.The MH method takes advantage of the features of Huffman codes and One way to simplify this is to use the Modify Hamaman coding method, which is defined as a standard coding method by the CCITT (Consultative Committee for International Telegraph and Telephone). For several 1,728 pixels, the run length from O to 1,728 is divided into groups of 64, and is represented by a combination of a code representing each group and a code indicating the length of the run within that group. 15 compresses the multi-valued image output 11 whose frame data has been identified by the image identification circuit 9 as a natural image forming a multi-valued image (multi-gradation image). This is a compression circuit using an adaptive discrete cosine transform method.This method is a discrete cosine transform (DCT), which is one of orthogonal transforms.

This converts an image signal of a small block composed of 8×8 pixels into a two-dimensional frequency component, specifically, a discrete cosine coefficient of 8×8 pixels.

According to this conversion, most of the power is concentrated in the low-order components compared to the high-order components. This is used to compress the image signal. In the adaptive discrete cosine transform method, linear quantization is performed on each discrete cosine coefficient using separate thresholds that take visual characteristics into account, and this quantization result is subsequently developed for each image to determine the optimal It creates and encodes a Huffman code, and is effective for data compression of self-thermal images that constitute multi-tone images. ] 4 is a recording medium for recording the compressed output 13 of a character image by the MH compression circuit 12 and the compressed output 16 of a natural image by the adaptive discrete cosine compression circuit 15. The recording medium 16 is, for example, an SRAM semiconductor memory integrated circuit (IC).
A rewritable digital storage device mounted in the form of a module such as a card or cartridge.

The operation will be explained based on the above configuration. Imaging lens 1
The image signal captured under the control of the aperture 2 is sent to the processing circuit 3.
The signals are converted into luminance signals and color difference signals. Processing circuit 3
These image amount J signals 4 are converted into digital data by an analog-to-digital converter 5. This digital data 6 is stored in the frame memory 7 for every l frame constituting one screen. Frame data 8 output from the frame memory 7 is transferred to an image identification circuit 9, which identifies whether the image is a character image (binary image) or a natural image (multivalued image). For identification, various methods are known, and in the embodiment, a method of checking the run length of the entire image is used. This method utilizes the feature that there is a large difference in the appearance rate of on and off run lengths between natural images and text images.

In a certain bitplane, it is turned on with a natural image and a text image,
The number of occurrences is checked for the run lengths that cause a difference in the appearance rate of OFF run lengths, and if there is a large correlation between the number of occurrences of ON and OFF, it is determined that it is a natural image, and otherwise, it is determined that it is a character image. Natural image data 11 identified as a natural image by the image identification circuit 9 is input to the compression circuit 15, and compression processing is performed on this data. This compression process is performed as a discrete cosine transform (DCT), and this process has an effective compression effect on natural images that constitute multivalued images. The character image data 10 identified as a character image by the image identification circuit 9 is input to the compression circuit 2, where compression processing is executed on the data. The compression process is performed as an encoding process using the so-called MH method, and this process has an effective compression effect on character images forming a binary image. The natural image compressed data outputted by the compression circuit 15 using the discrete cosine transform]6 and Ml (the compressed character image data 13 outputted from the compression circuit 12 using the encoding process according to the method are recorded on a recording medium)4.

(Effects of the Invention) As described above, the present invention identifies natural images comprising multiple gradations and character images comprising two gradations from images of a subject captured by a camera, and each of the identified images. Since each image is compressed using a compression method that effectively produces compression effects according to its characteristics, the number of recorded images that can be recorded on recording media such as floppies and IC cards can be increased and running costs can be reduced. It has the technical effect of being able to.

[Brief explanation of the drawing]

The figure is a functional block diagram of an embodiment of the present invention. 5...Analog-digital converter, 7...Frame memory, 9...Image identification circuit, 12...Ml (compression circuit using method encoding processing, 1)...Compression circuit using scattered cosine transformation processing , 14. Recording medium.

Claims (1)

[Scope of Claims] 1. An image information input means for inputting compressed image information, an image information storage means for storing the image information input by the image information input means, and an image information storage means for storing the image information input by the image information storage means. In an image information retrieval device having an image information decompression means for decompressing image information and an image information display means for displaying the image information, M from the image information stored in the image information storage means is provided.
A screen information retrieval device characterized by comprising an image information retrieval means for retrieving ×N pieces of screen information to be displayed on one screen by the image information display means. 2 In the above M×N, M=2^m, N=2^n, (m
, n are positive integers). 3 The compressed image information is subjected to orthogonal transformation.