JPH0253761B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image display method, and more particularly to an image display method capable of displaying a binary image with a large number of pixels, such as a document image.

In recent years, there has been active development of facsimile machines that enable cut-and-paste editing of documents, document image file devices that can store document images on optical disks or magnetic disks, and retrieve them as needed. In order for such devices to be easy to use and familiar to users, it is desirable that they be equipped with a display that can display document images in some form. However, currently available scanning displays only have a resolution of about 1000 lines at most; on the other hand, if an A4 size document is scanned at 8 lines/mm, the number of pixels will be about 1728 x 2400, and the entire document will be displayed. It becomes very impossible to do so.

Conventionally, two methods have been used in such cases. One method is to partially display a document image. That is, only a partial area of a displayable size on the document image is displayed, and the display area is changed using a scroll function. Although this method is very simple, it has the disadvantage that the entire document image cannot be displayed at once, making operations cumbersome during cut-and-paste editing.

Therefore, as a method for displaying the entire document image at once, a reduced display method has been considered. That is, a binary image with a size of m x n is reduced to a size of M x N and displayed, and the pixel values at the time of display are calculated by logical calculation of the values of several pixels on the original image. This is a method to determine the result. for example,
When displaying the entire document by reducing it to 1/2, if there are two or more pixels of 2x2 on the original image that are 1 (black), it is set to 1, and if there is one or more, it is set to 0.
This is how it looks when displayed as (white). 1st
The figure shows an example in which an 8x6 binary original image is reduced to 4x3 and displayed. A is the original image, and b is the reduced image.

When performing reduced display as described above, the number of scans is reduced, so deterioration in image quality is essentially unavoidable. An example is shown in FIGS. 2a and 2b. Three scanning lines as shown in Figure 2a are 1.
When a periodic pattern in which the number of books is 0 is given, the display image becomes all 1's as shown in FIG. 2b in the reduction calculation method described above. In order to avoid this, it is necessary to change the method to one in which 3 or more 1s are set to 1, and 2 or less to 0, but if this is done, the displayed image will all be 0 in Figure 1 b. .

As described above, conventional methods have the disadvantage that only a portion of the document can be displayed, or even if the entire image can be displayed, the image quality is severely degraded.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an image display device that can display a document image in whole or in part with less deterioration in image quality. It is in.

The present invention relates to an image display method in which image data, which is a set of binary data, is subjected to reduction processing and visually displayed by a display means. and data corresponding to
data corresponding to positions around the predetermined position, obtain single multivalued data from these plurality of data, and display this multivalued data at a predetermined position on the display screen of the display means. It is characterized by displaying the image data by using it as density information, and by adopting such a method, it is possible to perform magnification conversion display without deteriorating image quality even on a CRT with few scanning lines. Features.

The present invention will be described in detail below with reference to the drawings.

First, the principle of the present invention will be explained using FIGS. 3 and 4. The original images shown in Figures 3a and 4a are
They correspond to those in FIG. 1a and FIG. 2a, respectively.

In the present invention, the values of picture elements in a 2×2 area in the original image are added as shown in FIGS. 3b and 4b, and then normalized using the maximum value. The displayed image is then represented by 2 bits/pixel as shown in FIGS. 3c and 4c.

As can be seen by comparing Figures 1 and 2 with Figures 3 and 4, the feature of the present invention is that the reduction in the number of scans due to reduced display is compensated for in the density direction. Therefore, image quality deterioration can be significantly reduced.

An embodiment of the present invention is shown in FIG.

In FIG. 5, 1 is a document image input section, and the document image scanned there is processed by a binarization circuit 2, with black 1, black 1,
It is binarized to white 0 and stored in the page memory 3. Page memory 3 has a capacity of 1728 x 2304 x 1, and can store 8 A4 size documents.
Images scanned at book/mm can be stored. The contents of the page memory 3 can be output to the document image output unit 4 as required. Reference numeral 5 denotes a binary/multiple value conversion circuit, which includes a display position determination circuit 5-1 that calculates the position of a point in the page memory corresponding to each pixel of an image for display, and an output of this determination circuit 5-1. A picture element selection circuit 5- that selectively outputs information about the surrounding picture elements from the page memory 3 based on
2, and an arithmetic circuit 5-3 that calculates data of a picture element for display as multi-value data from the binary data of the selected picture element. Binary multi-value conversion circuit 5
The specific configuration has been realized by an image enlargement/reduction device previously proposed by the inventors (see Japanese Patent Application No. 166,815/1983). In the example, the calculation result is
After storing it in the display memory 6 with a capacity of 512 x 512 x 4 at 4 bits/pixel, it is displayed on the CRT display 7. Further, 8 is a display device control unit which controls the page memory 3, the binary/multiple value conversion circuit 5, the display memory 6, and the CRT 7.

According to the present invention, even a CRT with only about 500 scanning lines, such as a normal ITV monitor, can provide sufficient image quality to grasp the entire image of a document, and can be used for editing facsimiles, document file devices, etc. When connected to the device, the operability of the device can be significantly improved. Furthermore, in the case of documents in which dense flame information is expressed in a binary manner, such as halftone photographs in newspapers or dithered images in facsimiles, the effects of the present invention are particularly significant. It is possible to obtain a display image of good quality.

In the above embodiment, an image enlarging/reducing device is used as the binary/multi-value conversion circuit, but the same effect can be obtained by using the addition normalization method described in the principle section. Furthermore, in the present invention,
Although the binary and multi-value conversion data is displayed after being stored in the display memory, it is also possible to display it directly using a high-speed arithmetic circuit.

[Brief explanation of the drawing]

Figures 1a, b and 2a, b are diagrams for explaining the conventional reduced display method, and Figures 3a,
4a, b, and c are diagrams for explaining the reduced display method according to the present invention, and FIG. 5 is a block diagram showing an embodiment of the present invention. 1...Document image input section, 2...Binarization circuit, 3
...Page memory, 4...Document image output section, 5
...Binary-to-multivalue conversion circuit, 6...Display memory,
7...CRT display, 8...Display device control unit.

Claims (1)

[Scope of Claims] 1. In an image display method in which image data, which is a set of binary data, is subjected to reduction processing and visually displayed by a display means, the display screen of the display means is selected from the image data to be displayed. Identify the data corresponding to the predetermined position above and the data corresponding to the surrounding positions of the predetermined position, obtain single multi-value data corresponding to these multiple binary data, and An image display method characterized in that the image data is displayed as multi-value density information at a predetermined position on a display screen of the display means. 2. The image display method according to claim 1, wherein the image data to be displayed is stored in a memory. 3. Claims characterized in that the data corresponding to each of the predetermined position and the surrounding positions of this position are selected from image data to be displayed in accordance with the magnification of the image displayed by the display means. The image display method described in item 1. 4. The image display method according to claim 1, wherein the single multivalued data is data obtained by adding and normalizing a plurality of data. 5. The image display according to claim 3, wherein the single multivalued data is data obtained by performing calculations on a plurality of data according to the scaling ratio of the image on the display means. method. 6. The image display according to claim 2, wherein the predetermined position on the display screen is obtained by calculating a position corresponding to each picture element for display in memory. method. 7. The image display method according to claim 1, wherein the display means is a CRT.