JPS62164376A - Picture data restoration device - Google Patents

Abstract

PURPOSE:To attain continuous compression processing and to improve a compression efficiency by reproducing picture data made of reference picture elements in a reference line memory so as to refer. CONSTITUTION:While dot photographic data or character pattern data is restored according to layout information, it is developed in an image development memory 26, and sequentially outputted to a film recording device. The memory capacity of the image development memory 26 has lines enough to retain picture data composed of reference picture elements, which is used for restoring picture data. A means selectively inputting data to a reference line memory 3 from the image development memory 26 is provided. To prepare the restoration of the part (d) of a next photograph P2 after restoration, for instance, a part (e) of a photograph P, the necessary range of the picture data on the photograph P2 is copied to the reference line memory 3 from the image development memory 26. With said range as reference data restoration processing is completely executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to an image data restoration device that performs restoration of image data using a predictive coding method in 2J'Ii cycles for each few lines for a plurality of images. By reproducing pixel image data into the reference line memory, continuous compression processing is possible and compression efficiency is improved.

[Industrial application field]

The present invention relates to an image data restoring device, and particularly to an improvement of an image data restoring device that performs image data restoring from an image signal compressed by a predictive coding method by cyclically performing image data restoration on a unit of a few lines for a plurality of images.

Predictive encoding methods predict the image data of a target pixel by focusing on the correlation between adjacent pixels, encode the prediction error data, and compress the transmitted information. In the system being manufactured, it is often necessary to cyclically restore multiple halftone photographic data in units of a few lines, which poses a problem in system configuration as described below, and improvements are desired. .

[Conventional technology]

The amount of information in an image is generally enormous, and there is a great deal of redundancy. Therefore, when digitally processing an image, it is necessary to compress it to a minimum.

When digitally processing an image, it is usually subdivided into pixels and the data of each pixel is processed into binary signals, but if the image has gradation, such as a photograph, the pixels are processed after halftone dots are formed. It is subdivided.

Various methods have been proposed for compressing this digitized signal, and for example, the present inventors have provided a method for encoding halftone images in Japanese Patent Application No. 170832/1983. In the encoding according to the invention, as illustrated in FIG.
A plurality of pixels each belonging to a plurality of halftone dots existing in the vicinity of the halftone dot to which the target pixel X belongs, and located at the same phase position as the target pixel X,
For example, let a and C1d be reference pixels, and furthermore, the target pixel X
Neighboring pixels of, for example, s, b', b''; neighboring pixels of reference pixels c, d at the same phase positions, such as C'', C'', do, d
” is used as a reference pixel to generate prediction error data.

In such an encoding method, most of the reference pixels near the first line of the image are blank pixels outside the image area, and the compression efficiency is low, but the compression efficiency of the entire image is significantly improved.

For example, in systems that edit and produce newspaper pages using electronic computers, the amount of information involved is enormous, so it is difficult to compress and restore manuscript pages in the same way as with facsimiles. A sheet of paper containing halftone photographs P1, P2, P3, P4, etc., as exemplified in FIG. 5, is conventionally processed as follows using a system configured as shown in FIG. 6 and using an image data restoration device as shown in FIG. are doing.

However, in FIG. 6, 21 is a CPU, 22 is an ink face circuit, 23 is a character pattern generator, 24 is a layout information file, 25 is an image file such as a photograph, 26 is an image expansion memory, 27 is an image data restoration device, 28 is a film recording device, and in FIG. 7, 1 is a decoding circuit, 2 is a restoration memory, 3 is a reference line memory, 4 is an output sofa memory, 5 is a multiplexer,
6 is a predicted value table, 7 is an ink face circuit of the image data restoration device, and 8 is a reception buffer.

In this system, character pattern data or halftone photo data is restored and developed in the image development memory 26 according to the layout information, and this is sequentially output to the film recording device 28.
As shown in the figure, the storage capacity is usually only about a few tens of lines per page width strip, and the image is developed - output - by traversing the photos P1, P2, and P3 in units of a small number of lines, which are equal to or smaller than this. Image development and output are repeated periodically. In order to perform this with one image data restoration device, for example, after restoring part e of photo P1, it is necessary to clear the reference line memory 3 in order to restore the image data of part d of the next photo P2.

In addition, when each photo is sequentially compressed as one unit, it is not possible to expand all of the restored image data of each photo on the image expansion memory 26 as described above, and each photo is restored by cycling, so it is necessary to refer to the correct image data at the time of restoration. Data cannot be obtained and an error occurs. In order to avoid this error, each photo should be compressed and restored by considering a small number of lines corresponding to the number of lines in the image expansion memory 26 as one document, and setting all reference line data before this unit to "0". Must.

[Problem that the invention seeks to solve]

In systems where memory capacity is limited compared to the amount of information, such as a system that edits and produces new newspaper pages, conventional image data restoration devices cannot continuously compress image data as described above, resulting in a huge amount of information. Despite ff
The E' compression efficiency is extremely low, and there is a strong demand for its improvement.

[Means for solving problems]

The problem is that when performing image data restoration using the prediction error data of a target pixel and the image data of a reference pixel corresponding to the target pixel, the reference pixel is This problem is solved by the image data restoring device according to the present invention, which reproduces the image data in the reference line memory and references it.

[For production]

According to the present invention, by reproducing image data of necessary reference pixels in a reference line memory in which a part of the restored image data has been cleared, it is possible to restore continuously compressed data, even under the above-mentioned conditions. Achieve efficiency.

The image data of the reference pixel can be reproduced by, for example, providing means for inputting the image data of the reference pixel into the reference line memory from outside the image data restoration device, or by storing at least a part of the restored image data for each image. and a means for transferring the image data of the reference pixel from the storage means to the reference line memory, or the image data of the reference pixel is obtained by discarding the image data that has been overlaid and restored from the first line of the image including the target pixel. This is realized by providing a means for reproducing data.

〔Example〕

The present invention will be specifically explained below using examples.

FIG. 1 is a block diagram showing a first embodiment of the present invention.

This embodiment is a method that can be applied when the storage capacity of the image expansion memory 26 of the system has a sufficient number of lines to store image data of reference pixels used for image data restoration. For example, after restoring part e of photograph P1, in preparation for restoring part d of photograph P2, means is provided for selectively inputting data into reference line memory 3.
6 to copy the required range of image data of photo P2.

The restoration process is completely executed using this as reference data.

Next, FIG. 2 is a block diagram showing a second embodiment of the image data restoration apparatus according to the present invention.

In this embodiment, in addition to the conventional reference line memory 3, a plurality of memory areas 12a, 12b, . Before clearing the reference line memory 3 for this purpose, one of these memory areas, for example 12a, is selected and the required contents of the restoration memory 2 and the reference line memory 3 are copied or saved therein. Photo P2
In restoring portion d of photo P3 and portion 3 of photo P3, the restored image data is similarly stored in other memory areas.

When returning to the photo PL and restoring the part f, the memory control circuit 13 transfers the data in the memory area 12a to the reference line memory 3, and performs the restoration process using the image data of the reference pixels contained therein. conduct.

FIG. 3 is a block diagram of a third embodiment of the present invention.

In this embodiment, for example, when restoring part e of photo r"l, image data is restored from the first line to the immediately preceding part d, discarding data that does not need to be used as reference data, and restoring the necessary pixels. With the data stored in the reference line memory, restoration of a new portion e is started.This process is performed by, for example, controlling a gate circuit 14 provided between the output sofa memory 4 and the ink face circuit 7 with the line counter 15. This can be easily realized by

The above explanation refers to images expressed as halftone dots such as photographs, but the selection of reference pixels for target pixels is particularly controlled @
In addition, the encoding method for prediction error data can be arbitrarily selected.

〔Effect of the invention〕

As explained above (according to the present invention), continuous compression processing is possible in an image data restoring device that performs image data restoration from an image signal using a predictive coding method in cycles for each small number of lines for a plurality of images. As a result, a significant improvement in compression efficiency is achieved.

[Brief explanation of drawings]

Figures 1, 2 and 3 are block diagrams showing embodiments of the present invention, Figure 4 is a diagram showing an example of reference pixel selection in a halftone image, and Figure 5 is a schematic diagram showing image restoration processing. A plan view, FIG. 6 is a block diagram of the image restoration processing system, and FIG. 7 is a block diagram of the image data restoration device. In the figure, ■ is a decoding circuit, 2 is a restoration memory, 3 is a reference line memory, 4 is an output sofa memory, 5 is a multiplexer, 6 is a predicted value table, 7 is an ink face circuit of the image data restoration device, and 8 is a Reception buffers, 12a, 12b, . . . 12n are memory areas, 13 is a memory control circuit, 14 is a gate circuit, 15 is a line counter, 21 is a CP port, 22 is an ink face circuit, 23 is a character pattern generator, 24 25 is a layout information file, 25 is an image file such as a photograph, 26 is an image expansion memory, 27 is an image data restoration device, and 28 is a film recording device. Figure 3

Claims (1)

[Scope of Claims] 1) When image data restoration using prediction error data of a target pixel and image data of a reference pixel corresponding to the target pixel is carried out cyclically in units of a few lines for a plurality of images, An image data restoring device characterized in that the image data of the reference pixel is reproduced in a reference line memory for reference. 2) The image data restoration device according to claim 1, further comprising means for inputting the image data of the reference pixel into the reference line memory from outside the image data restoration device. 3) A patent characterized in that it comprises means for accumulating at least a portion of restored image data for each image, and means for transferring image data of the reference pixel from the accumulation means to the reference line memory. An image data restoration device according to claim 1. 4) The apparatus further comprises means for discarding image data that has been overlaid and restored from the first line of the image including the target pixel, and regenerating the image data of the reference pixel. Image data restoration device.