Computer graphics processing and selective visual display system – Display driving control circuitry – Controlling the condition of display elements
Reexamination Certificate
1999-12-08
2003-06-03
Cabeca, John (Department: 2173)
Computer graphics processing and selective visual display system
Display driving control circuitry
Controlling the condition of display elements
C345S215000, C345S215000, C345S215000, C345S215000
Reexamination Certificate
active
06573915
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to computer software, and specifically to programs enabling capture, storage and communication of the contents of computer displays.
BACKGROUND OF THE INVENTION
There are a variety of computer screen capture tools known in the art. These tools enable the contents and appearance of a computer screen to be captured, or recorded, more or less in real-time. Generally, a sequence of screens is captured and is then stored to disk and/or transferred to another computer. Screen capture tools of this sort are useful, for example, in educational applications and in training and promotional demonstrations. Screen capture is also used by computer remote control tools.
Screen capture products for education, training and promotion include Lotus ScreenCam (http://www.lotus.com/ screencam), Hyperionics HyperCam (http://www.hyperionics. com) and TechSmith SnagIt/32 (http://www.techsmith.com) These products enable a user to record the contents of a computer screen to a file, while the computer is carrying out another program, and then to reproduce the recorded screen content from the file. They evidently work by encoding a bitmap image of the entire contents of the screen. Multiple screens in sequence may be recorded by encoding the differences between successive screens. This approach usually generates large amounts of processed data and very large output files. As a result, users may be limited to working at very slow refresh rates, on the order of one or a few frames per second, if they wish to record a full, active computer screen. Transferring the output files over a low-bandwidth computer network may be even slower. The alternative is to compromise on the content of the recording, typically by reducing the color resolution, by recording only a portion of the screen, or by simplifying the screen contents, by reducing the number of windows that are open on screen, for example.
OPTX International ScreenWatch (http://www. screenwatch.com) uses an alternative approach of capturing data sent to the computer's display driver, in this case a proprietary driver developed for this purpose by OPTX. The display driver runs on a Microsoft Windows NT computer, which conveys the data to a separate client computer for recording. The data are stored in a proprietary format, which can subsequently be played back using a dedicated player program. The alternative approach employed by ScreenWatch enables faster, more efficient screen capture, but is limited to the complex, proprietary operating environment for which it was designed.
Computer remote control tools include Symantec PCAnywhere (http://www.symantec.com/region/can/eng/ product/pcanywhere) and LapLink.com LapLink (http://www.travsoft.com/products/llpro). These products enable a remote user to control a host computer and observe the screen contents of the host. They are not capable of keeping up with large or rapid changes on the host computer screen, even at high transmission bit rates between the host and remote computers.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide improved tools for computer screen capture and playback.
It is a further object of some aspects of the present invention to reduce the volume of data required to capture complex computer screen contents.
It is still a further object of some aspects of the present invention to increase the frame rate at which computer screen contents can be captured.
It is yet another object of some aspects of the present invention to provide tools for computer screen capture that are applicable to a wide range of platforms and can be played back by a platform-independent player.
In preferred embodiments of the present invention, a computer screen capture tool treats windows on the computer display as objects, and records changes in the characteristics of these objects and relations among them from frame to frame. Preferably, a group of typical transformations of the windows is defined, and these typical transformations are encoded and recorded separately from other changes in the window contents. Generally speaking, the typical transformations are defined by an operating system of the computer, and they are therefore common to windows running different applications and can be encoded very compactly for all of the windows on the screen. In this way, the amount of bitmap data that must be recorded is substantially reduced relative to screen capture tools known in the art.
Displays with multiple active windows can thus be recorded and transmitted in real time, with high temporal resolution (i.e., high frame refresh rates), as well as full color definition and detail, while the computer is carrying out application tasks. No special resources are needed, in contrast to products known in the art such as the above-mentioned ScreenWatch. Different encoding schemes can be applied to the contents of different windows, depending on the type of contents (for example, video as opposed to text). In some preferred embodiments, movements of other on-screen objects, such as a mouse-driven cursor and other icons, are also encoded using typical transformations.
To play back the recorded screens, the windows and other objects are reconstructed in each successive frame by applying the encoded typical transformations to the windows and objects in the preceding frame. The window contents are then reconstructed inside the windows. Preferably, a screen player program for reconstructing the recorded screens is independent of the operating system of the recording computer. Most preferably, the screen player is provided in a platform-independent form, for example, in the Java language.
Preferred embodiments of the present invention are useful in a range of applications, including demonstrations and presentations, education and remote control, as described in the Background of the Invention.
There is therefore provided, in accordance with a preferred embodiment of the present invention, a method for capture of computer screens in a sequence of frames, including:
identifying a first set of one or more windows appearing in a first frame in the sequence, each window in the set having respective first-frame window characteristics and window contents;
encoding a description of the first set of windows indicative of the appearance of the computer screen in the first frame;
identifying in a second frame in the sequence a second set of one or more windows having respective second-frame window characteristics and window contents, the second set including one or more windows corresponding respectively to one or more of the windows in the first set;
determining one or more transformations applied to the first-frame window characteristics of the windows in the first set to generate the second-frame window characteristics of the corresponding windows in the second set; and
encoding a description of the second set of windows including the determined transformations, for use in reconstructing the computer screen as it appeared in the second frame.
Preferably, identifying the first set of windows includes identifying windows generated in accordance with an operating system of the computer, which associates each window with a respective function of the computer, such that the contents of the windows are determined by the respective functions. Most preferably, the respective functions include applications running under the operating system. Further preferably, determining the transformations includes defining transformations applied by the operating system, and which are applicable to different windows associated with different functions, generally irrespectively of the functions. Preferably, identifying the second set of windows includes querying the operating system regarding the characteristics of the windows. Additionally or alternatively, identifying the second set of windows includes intercepting events generated by the operating system.
In a preferred embodiment, identifying the first set of windows includes processing an image of the screen
Kupeev Konstantin Y.
Sivan Zohar
Cabeca John
Darby & Darby
Thai Cuong T.
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