JP2001036830A - Resolution converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resolution converter of a television receiver to enable video display of optimal resolution of a natural image and a text image by converting resolution according to these images in a video signal. SOLUTION: This resolution converter is constituted so as to detect pattern levels of black to white levels of an image signal by an appearance ratio detecting circuit 15 when the resolution of the video signal inputted in an input terminal 11 is converted by a resolution converting circuit 13, to select an interpolation system and an interpolation coefficient optimal for resolution conversion of video based on the pattern level data by a microcomputer 16 and to control a resolution conversion processing of the resolution converting circuit 13 by the selected interpolation system and the interpolation coefficient.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resolution converter for optimizing the resolution of an image reproduced and displayed on an image display means according to the picture level of an image signal.

[0002]

2. Description of the Related Art In recent years, an image display device such as a television receiver has a function of receiving / reproducing and displaying a teletext signal multiplexed on a television signal, in addition to receiving / reproducing a television signal transmitted from a television broadcasting station. It has a function of displaying a video information signal including graphic characters created by the device. The television signal also includes a natural image and a character graphic image.

[0003] The television receiver reproduces and displays a natural image of a television signal and a character / graphic image (hereinafter referred to as a character / graphic image) based on the character / graphic image in the television signal or the text broadcast signal and a video information signal from a computer device. In particular, when displaying the text image in an enlarged or reduced manner, interpolation processing is performed to convert the resolution of the video in order to display the image in detail. I have.

[0004] However, when resolution conversion adapted to the definition of the text image is performed, the natural image becomes an unnatural image, and when resolution conversion adapted to the natural image is performed, the definition of the text image decreases. , Resulting in a blurred image. For this reason, it is common to use an interpolation method and an interpolation coefficient under certain conditions for resolution conversion.

[0005]

Conventionally, in an image display device such as a television receiver, a resolution conversion process of a video is performed in order to improve the definition of a video to be reproduced and displayed. And the interpolation coefficient are set under certain conditions. For this reason, in the video reproduced and displayed on the television receiver, the definition of the text image decreases when the quality of the natural image is prioritized, and the unnaturalness of the natural image increases when the priority of the text image is prioritized. There was a problem that would be.

[0006] In view of the above circumstances, the present invention performs resolution conversion in accordance with a natural image and a text image in a video signal,
It is an object of the present invention to provide a resolution conversion device for a television receiver that can display an image with the optimum resolution of the two images.

[0007]

According to the present invention, there is provided a resolution conversion apparatus comprising: a picture level appearance ratio detecting means for detecting a picture level of a received video signal; and a picture level corresponding to the picture level detected by the picture level appearance rate detecting means. An interpolation method determining means for selecting an interpolation method and generating an interpolation coefficient suitable for the method;
Using the interpolation method selected by the interpolation method determination means and the generated interpolation coefficient, a resolution conversion means for converting the resolution of the video signal, and demodulating and reproducing the video signal whose resolution has been converted by the resolution conversion means. Video playback means for displaying the playback video.

The interpolation method determining means of the resolution conversion apparatus of the present invention uses a microcomputer and selects a resolution interpolation method and an interpolation coefficient based on the picture level of the video signal detected by the picture level appearance detecting means. Is calculated.

The resolution conversion apparatus of the present invention can obtain an interpolation method and an interpolation coefficient for optimal resolution conversion according to a picture of a received video signal, so that a natural image can be displayed as a more natural image. The text image can be displayed as a video with higher definition, and the image quality of the displayed video is improved.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a resolution conversion apparatus according to the present invention.
FIG. 4 is an explanatory diagram of a picture level of a video signal processed by the resolution conversion device of the present invention.

First, the difference between a natural image and a text image will be described with reference to FIG. The horizontal axis of FIG. 2 indicates the level from the black level (LSB) to the white level (MSB).
The vertical axis indicates the level appearance ratio. The solid line indicates a text image, and the dotted line indicates a natural image.
As can be seen from FIG. 2, the text image has a picture level in which the appearance ratio is concentrated on the black level (LSB) and the white level (MSB). (LSB) and a white level (MSB).
The present invention has been made by paying attention to the difference in the picture level between the text image and the natural image.

Next, the configuration of the present invention will be described with reference to FIG. Reference numeral 11 in the figure denotes a not-shown television signal tuning tuner, intermediate frequency amplifying means, video / audio /
An input terminal to which an analog video signal demodulated through a signal processing circuit such as a synchronizing signal separating unit is input. The analog video signal input to the input terminal 11 is an analog video signal.
It is converted into a digital video signal by a digital conversion circuit (hereinafter, referred to as an A / D circuit) 12. The digital video signal converted by the A / D circuit 12 is supplied to a resolution conversion circuit 13 and an appearance ratio detection circuit 15. Resolution conversion circuit 13
Performs video resolution conversion of the supplied digital video signal based on an image interpolation method and an interpolation coefficient described later. The digital video signal whose resolution has been converted by the resolution conversion circuit 13 is converted into an analog video signal by a digital / analog conversion circuit (hereinafter, referred to as a D / A circuit) 14, and an analog signal (not shown) is output from an analog signal output terminal 17. It is supplied to a display device such as a cathode ray tube via a video signal processing circuit. The digital video signal whose resolution has been converted by the resolution conversion circuit 13 is supplied from a digital signal output terminal 18 to various digital devices and digital display devices (not shown) that perform digital video signal processing.

The appearance ratio detection circuit 15 is provided with the A / D
The appearance ratio of the picture level described in FIG. 2 of the digital video signal supplied from the circuit 12 is determined. That is, the appearance rate of the black level (LSB), the white level (MSB), and the intermediate level of the video signal is counted and detected, and the data of the detected appearance rate is calculated by a microcomputer (hereinafter, referred to as a microcomputer).
(Referred to as a microcomputer) 16. This microcomputer 16
Has a determining means for determining a picture of a video signal based on the picture level data, an interpolation method selecting means, and a calculating means for an interpolation coefficient, wherein the black level (LSB) and the white level (M
In the case of picture data concentrated in SB), it is determined that the image signal is a text image, and for example, a field or frame interpolation method is selected, and an interpolation coefficient between the preceding and following fields (or frames) is calculated. The resolution conversion circuit 13 is controlled to perform resolution conversion based on the selected interpolation method and interpolation coefficient, and when the picture level data is concentrated on an intermediate level, it is determined that the image is a natural image. While selecting the line interpolation method,
An interpolation coefficient between the preceding and succeeding lines is calculated, and the resolution conversion circuit 13 is controlled to perform resolution conversion based on the selected interpolation method and interpolation coefficient.

That is, the microcomputer 16 selects the most suitable interpolation method and interpolation coefficient for the resolution conversion according to the picture pattern based on the picture level appearance rate data detected by the appearance rate detection circuit 15. The resolution conversion circuit 1
3 is controlled so as to perform the resolution conversion processing based on the selected optimal interpolation method and interpolation coefficient.

Thus, the resolution conversion circuit 13 performs the optimum resolution conversion under the control of the appearance ratio detection circuit 15 and the microcomputer 16 according to the picture of the video signal input to the input terminal 11, and this optimum resolution conversion is performed. As for the text image of the video, an image with improved definition without blurring can be reproduced and displayed, and as for a natural image, an image free from unnaturalness can be reproduced and displayed. The input terminal 11 has other video sources (VTR, DTR) in addition to the television signal received by the tuner.
VD, etc.).

[0016]

According to the present invention, the optimum resolution conversion is performed in accordance with the pattern of the image, the text image is displayed clearly without blur, and the natural image is a natural image without unnaturalness. Image can be displayed, and the image quality of the image can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a resolution conversion device according to the present invention.

FIG. 2 is an explanatory diagram of a picture level of an image signal processed by the resolution conversion device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Input terminal 12 ... Analog-digital conversion circuit 13 ... Resolution conversion circuit 14 ... Digital-analog conversion circuit 15 ... Appearance ratio detection circuit 16 ... Microcomputer 17 ... Analog output terminal 18 ... Digital output terminal

Claims (2)

[Claims] 1. A picture level appearance ratio detecting means for detecting a picture level of a received video signal, and an interpolation method according to the picture level detected by the picture level appearance rate detecting means, and an interpolation method suitable for the method is selected. Interpolation method determining means for generating coefficients, resolution converting means for performing resolution conversion of the video signal using the interpolation method and the generated interpolation coefficient selected by the interpolation method determining means, And a video reproducing means for demodulating and reproducing the converted video signal to display a reproduced video. 2. The interpolation method determining means uses a microcomputer, and selects an interpolation method of the resolution converting means and calculates and generates an interpolation coefficient based on a picture level of a video signal detected by the picture level appearance detecting means. The resolution conversion apparatus according to claim 1, wherein the resolution conversion is performed.