Computer graphics processing and selective visual display system – Computer graphics processing – Character generating
Reexamination Certificate
1997-03-31
2001-05-15
Powell, Mark R. (Department: 2772)
Computer graphics processing and selective visual display system
Computer graphics processing
Character generating
C345S471000
Reexamination Certificate
active
06232987
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an outline font, and more particularly to a progressively renderable outline font(hereinafter referred to as a PR font) and methods of generating, transmitting and rendering the same.
BACKGROUND OF THE INVENTION
Generally, included within widely used graphical user environments, such as Windows 3.1, Windows 95, Windows NT, OS/2, UNIX X Window, Macintosh System 7, and Display Postscript, etc., are fonts and these fonts are displayed through a display device, such as a monitor. In these environments, postscript fonts of Adobe or true type fonts of Microsoft or Apple are widely used.
An outline font generally is composed of: information about the code map allotted to each character, information about the glyph indicating the shape of each character by specifying the positions of the control points, and hinting and other control information required for rasterization. This information is saved in a file called a font file.
Nowadays, approximately 1 to 10 MBytes are required to make a Korean or Chinese font. Therefore, up until now, this large amount of data has been a big hindrance to the on-line transmission of the outline characters via the network environment to another computer in a remote location which does not have the font to be used.
The normal procedure in displaying the font on a user's screen is that first, the computer's rasterizer must read the font file, and then generate a bitmap pattern. Then, the data is transmitted to the display device through a bus within a computer, or through a network, in the case of a network computer (the term ‘network computer’ is used to include all the computers with resources distributed in the network environment). However, a problem arises when the speed requirement of data transmission exceeds that which the hardware can support.
For example, when using a network computer, the font file and the rasterizer may be located in different places in the network. This perhaps is a very typical case when a TV or a simple set-top box is used as a network computer that accesses the internet. A simple solution is of course to first transmit the needed font file to the rasterizer of the network computer through the network. However, since the entire font file has to be sent before a single character can be displayed, this clearly is not an acceptable solution.
A similar problem arises when an internet user in America tries to browse a web site in Korea. If the data is written in Korean, the user in America must already have Korean font capabilities in order to display the data from the Korean web site. If the user in America does not have Korean font capabilities the entire Korean font file must first be transmitted to the user in America from the Korean web site before Korean characters can be displayed. In this case, if the size of the Korean font file is too large, a lot of time is required to transmit the data, and this again causes a big delay in displaying the Korean fonts.
Also, even when transmitting bitmap patterns through the bus within a computer, there is a situation in which a speed problem can arise. When fast browsing of a text file is required, all the glyph information of each character must first be read before the rasterization of the font begins. This causes some delay in quick displaying of the data when there is a large amount of glyph information. That is to say, a problem in the browsing speed can occur.
Until now, speed improvement methods like font cache have been used in font displaying. However, even these improvement methods cannot solve all the problems of the transmission speed when there is nothing in the cache.
SUMMARY OF THE INVENTION
Therefore, the present invention has been made in view of the above mentioned problems, and the present invention provides a progressively renderable font, the display quality and the transmission speed of which can be adjusted according to the requirements of the environment.
The progressively renderable font can adjust the speed of the display and the quality of the font in proportion to the environment and the objective. If the speed of the hardware is slow and a high quality font is not needed, only a part of the font data will be transmitted and displayed with a trade-off between the speed and display quality. On the other hand, if the speed of the hardware is relatively fast and a high quality font is needed, all the data will gradually be transmitted and displayed.
Therefore, when the environment does not allow, a font can be transmitted and displayed using minimal data. But when the environment allows, all the data can be transmitted and displayed so that the quality of the font can be fully realized.
In order to achieve the objective of the present invention, there is disclosed an outline font containing the glyph information of each character. The glyph information of each character comprises:
coordinates of control points composing each said character;
level information for transmitting or rendering each said character progressively; and
an indexing information for dynamically expressing progressive connection relationships between each of the said control points when each said character is rendered progressively.
Also, in another aspect of the present invention, there is disclosed the glyph information of each character. The glyph information of each character comprises:
information of the maximal inscribed circle containing a control point as a contact point for establishing each said character;
level information for transmitting and rendering of each said character progressively; and
an indexing information for dynamically indicating progressive connection relationships between each said maximal inscribed circle when each said character is rendered progressively.
Also, in another aspect of the present invention, there is disclosed a progressively rendering method. The method is formed by the steps of: first, extracting glyph information of each character of an outline font;
providing level and index information to each control point of each said character; and
establishing a progressively renderable font file by collecting information on each character provided in the above steps.
Also, in another aspect of the present invention, there is disclosed a progressively rendering method. The method is formed by the steps of: first, determining a rendering level in accordance with a request of a user or an environment, and transmitting only additional data into a designated apparatus, excluding the already transmitted information;
calculating an outline of each character with data transmitted up to current level; and
expressing each character progressively by rasterizing each said character using the outline obtained in the previous step.
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Fractal Coding of Chinese Scalable Calligraphic Fonts by Horace H. S. Ip et al. P/.343-351.
Adobe to link PostScript fonts to Web Pages via HTML 3 spec, Staten James, MacWeek, v10, n9,p4(1) Mar. 4, 1996.
Choi Hyeong In
Choi Sung Woo
Lee Sung Jin
Moon Hwan Pyo
Park Kyung Hwan
Blakely & Sokoloff, Taylor & Zafman
Harrison Chante′ E.
Hyundai Electronics Industries Co,. Ltd.
Powell Mark R.
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