Computer graphics processing and selective visual display system – Display driving control circuitry
Reexamination Certificate
2000-03-15
2003-07-22
Nguyen, Chanh (Department: 2675)
Computer graphics processing and selective visual display system
Display driving control circuitry
C345S213000
Reexamination Certificate
active
06597350
ABSTRACT:
TECHNICAL FIELD
This invention relates to an image reproduction device, an image reproduction method, and an information storage medium that enable the reproduction of digital dynamic image data from analog dynamic image data (a signal) that was generated as digital dynamic image data then was converted into an analog signal.
BACKGROUND OF ART
Ordinarily, digital dynamic image data that was generated as digital data by an image generation device such as a TV game machine is subjected to analog conversion to produce analog dynamic image data that can be displayed on a TV screen or CRT monitor or the like.
However, it is often convenient to work on image data, such as dynamic image data, as digital data when subjecting such image data to processing. Examples include superimposing captions on the image data or transmitting the image data over a network.
In such a case, it is necessary to subject that analog dynamic image data to analog-digital conversion such that it ends up as close to the original digital dynamic image data as possible, and reproduce it as digital dynamic image data.
During the reproduction of this digital dynamic image data that was fetched as analog dynamic image data, if the analog-digital conversion is done with no connection to the timing at which the original digital dynamic image data was generated, the phase and frequency of the sampling clock will differ from those of the sampling clock for the original digital dynamic image data and the thus-obtained digital dynamic image data could be vastly different from the original digital dynamic image data.
A method called over-sampling is used to ensure there is no such difference, but this doubles the amount of digital data that is handled, making it necessary to increase the operating frequency of the circuitry and thus making it necessary to use more precise and more expensive hardware.
There is another method of reproducing the digital dynamic image data by fetching it during the original digital dynamic image generation, before it is subjected to digital-analog conversion, but this necessitates special hardware and software, and is thus not practicable.
This invention was devised in the light of the above described technical problem and has as an objective thereof the provision of an image reproduction device, image reproduction method, and information storage medium that can take digital dynamic image data that has been subjected to analog conversion and reproduce digital dynamic image data therefrom that is substantially the same as the original digital dynamic image data.
DISCLOSURE OF THE INVENTION
(1) According to a first aspect of the present invention, there is provided an image reproduction device for taking analog dynamic image data (a signal) obtained by performing an analog conversion of digital dynamic image data that was generated on the basis of a predetermined dot clock, and reproducing the digital dynamic image data therefrom, the image reproduction device comprising:
synchronization signal input means for inputting a synchronization signal for the digital dynamic image data;
clock generation means for generating a sampling clock which has the same frequency as that of the dot clock and which is also at a phase that is adjusted on the basis of the synchronization signal; and
analog-digital conversion means for digitizing the analog dynamic image data, based on the sampling clock, to reproduce the digital dynamic image data.
According to a second aspect of the present invention, there is provided an image reproduction method for taking analog dynamic image data (a signal) obtained by performing an analog conversion of digital dynamic image data that was generated on the basis of a predetermined dot clock, and reproducing the digital dynamic image data therefrom, the image reproduction method comprising the steps of:
inputting a synchronization signal for the digital dynamic image data;
generating a sampling clock which has the same frequency as that of the dot clock and which is also at a phase that is adjusted on the basis of the synchronization signal; and
reproducing the digital dynamic image data by digitizing the analog dynamic image data, based on the thus generated sampling clock.
According to a third aspect of the present invention, there is provided computer-usable information embodied on an information storage medium for implementing (executing) the above described means or steps. As an example of the information, there is a computer-usable program for implementing (executing) the above described means or steps. This program could be embodied in a carrier wave.
If the type of image generation device that generates and outputs the analog dynamic image data is known, the dot clock frequency for the digital dynamic image data that forms the source of the analog dynamic image data is identified thereby. If, for example, the image generation device is a game machine, the frequency of the dot clock used by that game machine can be identified from the type of the game machine.
Thus the image reproduction device of this invention receives the analog dynamic image data and also the synchronization signal that was used during the generation of the digital dynamic image data that is the source of this analog dynamic image data.
A sampling clock is then generated, based on a frequency corresponding to the dot clock for the pre-analog-conversion digital dynamic image data, which has been previously identified, and the input synchronization signal, so that this sampling clock has the same frequency as the dot clock and also has a phase that is adjusted to be suitable for sampling.
The thus-generated sampling clock is then used for sampling the input analog dynamic image data and thus reproduce the digital dynamic image data.
In this manner, during the regeneration of the digital dynamic image data from the input analog dynamic image data (signal), the digital data for each dot that configures this reproduced digital dynamic image data has substantially the same value as the digital data for each dot that configures the original digital dynamic image data as it was before the analog conversion. As a result, the image reproduction device can obtain digital dynamic image data that is faithful to the source image, without using the over-sampling method.
Note that RGB luminance signals or the like can be included in this analog dynamic image data, for example.
The synchronization signal used in this case could be both of the vertical synchronization signal and the horizontal synchronization signal, but the horizontal synchronization signal alone could be used, by way of example.
(2) According to a fourth aspect of the present invention, there is provided an image reproduction device for taking analog dynamic image data obtained by performing an analog conversion of digital dynamic image data that was generated by an image generation device, based on a predetermined dot clock, and reproducing the digital dynamic image data therefrom, the image reproduction device comprising:
synchronization signal input means for inputting a synchronization signal for the digital dynamic image data;
storage means for storing frequency data corresponding to the dot clock;
selection means for selecting frequency data for generating a sampling clock, from the frequency data stored in the storage means;
clock generation means for generating a clock at the same frequency as that of the dot clock, based on the selected frequency data, then generating the sampling clock from the clock, with a phase that is adjusted on the basis of the synchronization signal; and
analog-digital conversion means for digitizing the analog dynamic image data, based on the thus generated sampling clock, to reproduce the digital dynamic image data.
According to a fifth aspect of the present invention, there is provided computer-usable information embodied on an information storage medium for implementing the above described means. As an example of the information, there is a computer-usable program for implementing the above described means. Thi
Moriguchi Akihiko
Sato Shigeru
Namco Ltd.
Nguyen Chanh
LandOfFree
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