 Noise reduction system for color television signal |
| According to one feature of this invention, there is provided a noise reduction system for a color ... |
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| Frequency converter for a digital chrominance modulator |
| It is an object of the present invention to provide a frequency converter circuit for converting ... |
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| Method and apparatus for video signal interpolation and progressive scan conversion |
| FIG. 1 shows scanned pixels in the vertical-temporal (v, t) plane. The small circles mark the ... |
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| Method for electronic image dynamic range and contrast modification |
| Image luminance first is separated into high and low frequency components. The low frequency ... |
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| Multi-format digital image pickup apparatus |
| OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram of an image pickup apparatus according to the ... |
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| Image pickup apparatus |
| The present invention has been made to solve the above-mentioned problems, and has as its first ... |
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| Visible light and near infrared imaging device |
| What is claimed is: 1. An imaging device comprising: an addressing means; an array of ... |
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| Noise reduction system for color television signal |
| What is claimed is: 1. A noise reduction system for reducing noise contained in a television video ... |
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| Video level control |
| According to the present invention there is provided a digital video coder comprising a video input ... |
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Television receiver that controls display contrast based on the type of videos being displayed
| Details |
Inventors: Sumiyoshi, Hajime; Namikawa, Takeshi;
Assignee: Kabushiki Kaisha Toshiba (Kawasaki, JP)
Primary Examiner: Peng; John K.
Assistant Examiner: Burgess; Glenton B.
Attorney, Agent or Firm: Cushman, Darby & Cushman
A television receiver includes a first signal processing unit that generates contrast controlled first R, G and B signals and a second signal processing unit that outputs second on-screen R, G and B signals. A switching unit receives the first and second R, G and B signals and selectively outputs one of them to a color CRT. An ABL voltage, which changes in response to a level of video displayed on the CRT, is provided to the first and the second R, G and B signals. A control unit determines whether to execute the contrast control of the second R, G and B signals based on a ratio of video corresponding to the second R, G and B signals out of the total video displayed on the color CRT. |
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DETAILED DESCRIPTION It is, therefore, an object of the present invention to provide a television receiver capable of eliminating the problem described above by selecting whether the contrast control should be executed on the on-screen display R, G and B signals corresponding to ABL voltage under prescribed conditions.
In order to achieve the above object, a television receiver according to one aspect of the present invention includes first signal processing means for receiving television signals and generates contrast controlled first R, G and B signals; second signal processing means for making it possible to control the contrast by inputting second on-screen R, G and B signals; switching means for inputting the first and second R, G and B signals from the first and the second signal processing means and selectively to outputting them; a color CRT to which selected outputs are supplied from the switching means for displaying video image by the selected outputs; means for generating an ABL voltage that changes corresponding to level of video displayed on the color CRT to supplying the voltage to the first and the second signal processing means for the contrast control of the first and the second R, G and B signals; and control means for controlling the execution and prohibition of the contrast control of the second R, G and B signals to execute the contrast control if a ratio of video by the second R, G and B signals out of the video displayed on the color CRT exceeds a prescribed level and to prohibit the contrast control if it is below the prescribed level.
According to a television receiver of the present invention, the control means executes the contrast control using the ABL voltage if a ratio of video by the second on-screen display R, G and B signals out of the videos displayed on the color CRT is in excess of a prescribed level while prohibiting the contrast control if it is below the prescribed level.
It is therefore possible to decide whether the contrast control corresponding to the ABL voltage should be executed or not according to a prescribed condition
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Image Analysis 
