MXPA98005852A - Vi signal processing circuit - Google Patents

Abstract

The present invention relates to a well-defined image correcting a contour of a video signal of a natural and similar image of a computer. Video signals, for example, of three primary colors (R, G, B), including a natural and similar image produced, for example, by a computer from the input terminals 1 are supplied to a mixer circuit (2) and are mixed at a ratio of, for example, 0.6G + 0.3R + 0.1B to produce a signal corresponding to a luminance (Y) This signal supplies the differentiation circuits 3A and 3B having different time constants one of the another and predetermined high-frequency components are extracted therefrom, respectively, and these output signals are selected by a switch (4), and then supplied to an amplifier circuit. The gain of the amplifier circuit 5 is controlled arbitrarily by a signal from a control terminal (6). Then, a signal from the amplifier circuit (5) is supplied to the summing circuits 7R, 7G and 7B and added to the respective video signals of R, G and B and then derived from the output terminals 8R, 8G and

Description

"VIDEO SIGNAL PROCESSING CIRCUIT" BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to a video signal processing processor circuit suitable for use, for example, in a presentation apparatus for a computer.

DESCRIPTION OF THE RELATED TECHNIQUE In a conventional presentation apparatus for a computer, for example, because a video signal produced by the computer is usually of high contrast, in such a way that the video signal is presented as it is in the apparatus of presentation without its contour being accentuated. In recent years, however, with the diffusion of an internet call, a CD-ROM and the like, it is carried out collecting a photograph, a natural image and a movie on a computer. In that case, a video signal picking up the natural image is different from a video signal produced by the conventional computer since, for example, its contour and similar parts are prone to be blurry. Therefore, when this video signal is presented in a presentation apparatus, a fear arises that a well-defined image can not be obtained.

COMPENDIUM OF THE INVENTION Therefore, in accordance with the present invention, a plurality of supported primary color signals are mixed at a predetermined ratio respectively, a high frequency component of the mixed signal is extracted and added to each of the plurality of color signals This means that the contour of video signals such as the natural or similar image can be corrected and a well-defined image can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a functional diagram showing the arrangement of an example of the video signal processing circuit according to the present invention; and Figures 2A, 2B and 2C, are waveform diagrams used to explain an operation of the video signal processing circuit shown in Figure 1.

DESCRIPTION OF THE PREFERRED MODALITY Briefly speaking, the present invention is arranged in such a way that a plurality of primary color signals are admitted and the plurality of supported primary color signals are mixed at a predetermined ratio, respectively, in order to produce a signal corresponding to a luminance and a high frequency component of the signal corresponding to the luminance and extracted and added to each of the plurality of primary color signals. Then, the present invention will be explained with reference to the drawings. Figure 1 is a functional diagram showing a structure of an example of an essential portion of a computer display apparatus to which a video signal processing circuit according to the present invention is applied. In Figure 1, for example, video signals of three primary colors (RGB) including a natural image produced, for example by a computer (not illustrated) are respectively supplied to the IR, IG and IB input terminals of a circuit of video signal processing in accordance with the present invention. The video signals of R, G and B of these input terminals IR, ÍG and IB are supplied to a mixer circuit 2 and mixed therein at a ratio of, for example 0.6G + 0.3R + 0.1B, where a signal corresponding to a luminance (Y) is produced therein. The signal corresponding to the luminance (Y) is supplied to the differentiation circuits 3A and 3B, each of them having a time constant different from each other, and the predetermined high frequency components are extracted therefrom, respectively. In addition, the output signals of these differentiation circuits 3A and 3B are selected by a switch 4 and supplied to an amplifier circuit 5. Also, the gain of the amplifier circuit 5 is controlled arbitrarily by a signal from a control terminal 6. As a result, a signal obtained by amplifying a predefined high frequency component of the signal corresponding to the aforementioned luminance (Y) with an arbitrary gain, is derived from the amplifier circuit 5. Then, the signal of the amplifier circuit 5 is supplied to the summing circuits 7R, 7G and 7B respectively provided in the signal paths from the input terminals IR, ÍG and IB, are added to the video signals of R, G and B therein and then derived from the output terminals 8R, 8G and 8B conducted outward from the summing circuits 7R, 7G and 7B, respectively. That is, in this circuit, when a video signal shown in Figure 2A is admitted to the input terminals IR, ÍG and IB with a lapse of time, a similar signal is derived from the mixer circuit 2. The signal is supplied to the differentiation circuits 3A and 3B, and a predetermined high-frequency component of the signal as shown, for example, in Figure 2B is extracted therefrom. Then, the high frequency component is added to the original video signal in the summation circuits 7R, 7G and 7B, whereby an output signal is produced as shown in Figure 2C. Also, in this circuit, since one of the differentiation circuits 3A and 3B, each having a time constant different from one another, is selected by the switch 4 and then it is used, it is possible to extract the high frequency component that corresponds to the natural and similar image collected by for example a computer. Furthermore, it is possible for the level of the high frequency component to be controlled by the amplifier circuit 5, in order to emphasize a desired high frequency and in this way to emphasize the contour of the image. As a result, the video signals of R, G and B, where the high frequency (contour) of the video signals admitted to the IR, IG and IB input terminals are emphasized, are derived from the output terminals 8R, 8G and 8B, respectively. Then, the outline of the natural or similar image is corrected and a well-defined image can be obtained by supplying the video signals from the output terminals 8R, 8G and 8B to a display apparatus such as a cathode ray tube (CRT), a liquid crystal display (LCD) apparatus. Accordingly, in this apparatus, when a plurality of primary color signals are mixed at a predetermined ratio respectively, the high frequency component of the mixed signal is extracted and added to each of the plurality of primary color signals, it can a well-defined image is obtained by the fact that the contour of the video signal of the natural or similar image is corrected. As a result, even though there has been fear until now that when the video signal of the natural and similar image is collected, for example, in the computer in which it will be presented in the presentation apparatus, the contour and the like have propensity to be fuzzy and a well-defined image can not be obtained, and these problems can be easily solved by the present invention. Also, when the differentiation circuits, each having a different time constant from each other or are selected and then used, it is possible to extract the high frequency component in accordance with the quality of the image and the like of the natural image collected for example, on the computer. In addition, by controlling the high frequency component level, it is possible to emphasize a desired high frequency (contour). In the case of a high contrast video signal generated by the computer, it may be possible that by selecting the differentiation circuits 3A and 3B, disconnecting the switch 4 or adjusting the gain of the amplifier circuit 5, the high frequency component has not been extracted or not added to a video signal, and the output signal is supplied. In this way, in accordance with the video signal processing circuit mentioned above, when a plurality of primary color signals are admitted, the plurality of the primary color signals admitted respectively, are mixed to a predefined ratio in order to produce a signal that corresponds to a luminance, and the high frequency component of the signal corresponding to the luminance is extracted to be added to each of the plurality of primary color signals, the outline of the video signals of the natural image and the like are corrected , thus making it possible to obtain a well-defined image. Therefore, in accordance with the invention, since a plurality of the primary color signals admitted respectively are mixed at a predetermined ratio, the high frequency component of the mixed signal is extracted and then added to each of the plurality of primary color signals, the outline of the video signal of the natural image and the like are corrected, and a well-defined image can be obtained. As a result, even though there has been the fear so far that when a video signal of the natural and similar image is collected, for example on the computer, and is going to be presented on the presentation apparatus, the outline and the like have for example propensity to be blurred and the well-defined image can not be obtained, these problems can easily be solved by means of the present invention. In accordance with the present invention, since the differentiation circuits, each having a time constant different from one another are selected and then used, it is possible to extract the high frequency component in accordance with the quality of the image and the like of the natural image collected for example, through the computer. In addition, by controlling the level of the high frequency component, it is possible to emphasize a desired high frequency (contour). Having described a preferred embodiment of the present invention with reference to the accompanying drawings, it should be understood that the present invention is not limited to the aforementioned embodiments and that various changes and modifications may be effected therein by those persons skilled in the art. technique without deviating from the spirit and scope of the novel concept of the present invention as defined in the appended claims.

Claims (4)

R E I V I N D I C A C I O N S

1. A video signal processing circuit, comprising: a means for being admitted with a plurality of primary color signals; means for mixing the plurality of primary color signals admitted to a predetermined reiation in order to produce a signal corresponding to a luminance; and a means for extracting a high frequency component from the signal corresponding to the luminance and adding the high frequency component to each of the plurality of primary color signals.

2. A video signal processing circuit according to claim 1, wherein the plurality of primary color signals are produced by a computer as well as the processed video signals are presented in a display apparatus.

3. A video signal processing circuit according to claim 1, comprising: a mixing circuit for mixing the plurality of primary color signals admitted at a predetermined ratio, respectively; a differentiation circuit for extracting a high frequency component from the signal corresponding to the luminance; an amplifier circuit for amplifying a signal from the differentiation circuit; and a summing circuit for adding a signal from the amplifier circuit to each of the plurality of primary color signals.

4. A video signal processing circuit according to claim 3, wherein the differentiation circuit selects a plurality of circuits having different time constants as well as providing a means for controlling a gain of the amplifier circuit.