JP2001024896A - Picture file format having character data independently of bit map data and its display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a file format which can clearly display characters even when the compression ratio of the characters is set at a high value at the time of keeping pictures containing the characters in a compressed state and a display device used for the format. SOLUTION: Firstly, an original picture is resolved into a character portion and a bit map portion from which characters are erased. The bit map portion is compressed by using an arbitrary compression method and recorded in part of a file together with a bit map identifiers (marker). The character portion is further divided into format information (type fonts, directions, character displaying positions, etc.), and text information (contents of texts) and both information are racorded respectively in parts of the file together with character information identifiers. A display device displays a bit map by expanding the compressed bit map portion upon finding the bit map identifier and, when the display device finds the character information identifiers, the device reproduces a character string bit map from the format information and text information and displays a character string by superposing the string upon the already displayed bit map.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a file format for recording an image including characters and a display device therefor.

[0002]

2. Description of the Related Art When an image file is handled by a computer, a compression method is used to reduce the data capacity.

[0003] Compression methods include a lossless compression method and an irreversible compression method. A typical file format using the lossless compression method is GIF (Graphics Interchange).
geoformat), a typical file format using a lossy compression method, JPEG (Joint Photo)
graphic Experts Group).

In recording a high-definition image such as a photograph, an irreversible compression method is mainly used because of a high compression ratio. Hereinafter, the present invention is also based on the lossy compression method.

[0005]

A disadvantage of the irreversible compression method is that the higher the compression ratio, the more the image is degraded, and the reproducibility of details at the time of display is deteriorated.

[0006] In particular, in an image containing fine characters, the deterioration of the character portion is more noticeable than other portions due to the characteristics of the human eye, and if the compression ratio is increased, the image quality is sufficient. In some cases, the character part is almost unreadable.

As a result, in an image containing fine characters, the character is sufficiently legible, which is the limit of the practical compression ratio, and as a result, there is a problem that the file size becomes large.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a file format in which characters are clearly displayed even when a high compression ratio is set, and a display device therefor.

[0009]

According to the present invention, first, an original image is decomposed into a character portion and a bitmap portion in which the character is deleted.

[0010] The bitmap portion is compressed using an arbitrary compression method, and is recorded in a part of the file together with a bitmap identifier (marker).

The character portion is further divided into format information (typeface, direction, character display position, etc.) and text information (text content).
Each is recorded in a part of the file together with the character information identifier.

In the display device, when a bitmap identifier is found, compression is expanded to display the bitmap. When a character information identifier is found, a character string bitmap is regenerated from format information and text information. The character string is displayed so as to be superimposed on the previously displayed bitmap.

In this way, even if the bitmap portion is highly compressed and becomes a very unclear image,
Characters can always be displayed clearly.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As an embodiment of the present invention, a case where a JPEG format representing a lossy compression format is used will be described below.

In a JPEG format file, the file content is segmented into several frames (regions) by an identifier called a marker.
9 (EOI). (Fig. 1)

Since a frame starting with a marker of 0xFFE0 to 0xFFEF can be arbitrarily defined by an application, character information is stored using this frame in the example of this embodiment.

FIG. 2 shows an example of a marker for storing character information.

FIG. 3 is a schematic diagram showing a case where an image is recorded / reproduced in a file format according to the present invention. Hereinafter, description will be made with reference to this figure.

First, a character portion is extracted from the original image data, and character frame data is created by adding format information.

On the other hand, the image frame data is created by irreversibly compressing the original image in which the character portion has been deleted according to the ordinary JPEG format.

The image frame data and the character frame data are recorded in the same file to form one image file.

When the display device finds the image frame data from the file, the compressed data in the image frame is expanded according to the JPEG format to reproduce and display the bit map.

Since the display of image frame data is the same operation as that of the display device of the prior art, if the display device that does not support the file format according to the present invention can display the conventional file format, the image frame portion is displayed. It is possible to display.

On the other hand, when the character frame data is found, the format information is read, and the character string bitmap is regenerated and displayed over the previously displayed bitmap data.

At this time, if the previously displayed bitmap data is displayed enlarged or reduced,
When displaying the characters of the character frame data, a similar enlargement / reduction ratio is applied to adjust the character size.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As an embodiment of the present invention, application to a comic book can be considered.

In a comic book, since there are very many characters in addition to the vividness of the image, the compression rate in the JPEG format is limited to about one fifth of the original image data in file size.

If the degradation of the image quality of the character portion is allowed, the compression can be made to about 1/10 of the original image data, and the conventional method requires about twice as much data.

On the other hand, in the file format and display device according to the present invention, the character information portion is added to the image data, but the character information amount (unit: bytes) is at most About 100 bytes,
Since it is sufficiently small compared to the image data (several tens of kilobytes), the size can be increased almost negligibly.

As described above, according to the present invention, there is an effect that the file size in which a comic book is recorded can be substantially reduced to about 1/10 of the original image and about 1/2 as compared with the conventional format.

As another embodiment, application to map data is conceivable.

Since map data has a lot of character information such as place names and building names, when it is stored in the JPEG format, it is difficult to read characters due to deterioration of image quality, and the practicality as a map is lowered.

For this reason, despite the high compression capability of the JPEG system, map data is rarely stored in the JPEG format in the past, and a lossless compression method such as GIF was used even when the file size became large. Often used.

According to the present invention, map data can also be saved at a high compression rate by applying the JPEG method, and the file size is reduced, so that convenience such as exchange of map data over a network is improved. Improve dramatically.

[0035]

According to the present invention, even if the image is compressed at a very high compression ratio, clear characters can be displayed regardless of the compression ratio.

Further, the compression ratio can be increased for data such as cartoon images and map images, for which the compression ratio could not be increased mainly due to the deterioration of the image quality of the character portion, and the capacity of the storage device for storage is increased. You don't have to squeeze.

Further, since the data size is reduced, the convenience of exchanging data on the network is dramatically improved.

Further, since character data is recorded as character codes separately from image data, conventionally, an optical character reading device (OCR: Optical Code Read) has been used.
Character information in an image that could only be identified by r) can be read at high speed and accurately.

Thus, a highly efficient compression method such as JPEG can be applied to a field where high precision is required, such as identification of a product code in an image.

[0040]

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of the structure of an image file according to the JPEG system.

FIG. 2 is a diagram illustrating an example of a character information identifier (marker) according to an embodiment of the present invention.

FIG. 3 is a schematic diagram showing an example of a procedure for recording and reproducing an image in a file format according to the present invention.

Continued on front page F-term (reference) 5C059 KK01 KK37 MA00 ME02 PP01 PP20 RC12 RC34 TA17 TB04 TC24 TD13 UA02 UA05 5C078 AA01 AA04 BA21 CA03 CA14 DA00 DA01 DB00 5C082 AA01 BA02 BA12 BA27 BB12 BB15 BB44 CA87 MM01 DA02 DD09 EE04 HH22 HH27 HH28 JJ11 JZ25 JZ78 KK45

Claims (2)

[Claims] In a file in which a bitmap image is compressed and recorded, a file format in which character data extracted from an original image and bitmap data in which a character portion is deleted from the original image are stored in the same file, and the file format are used. And a display device for displaying character data superimposed on bitmap data. 2. A recording medium on which a file stored in the file format according to claim 1 is recorded.