JPH06189162A - Vertical contour emphasizing method - Google Patents

Abstract

PURPOSE:To obtain desired picture quality corresponding to a source or a pattern to be displayed by calculating vertical contour emphasis signal by obtaining an optimum contour emphasis coefficient while referring to a memory, which is made into a look-up table(LUT) for storing contour emphasis coefficients, corresponding to the brightness change of a contour. CONSTITUTION:The absolute value 8 showing the degree of change in an input brightness signal is calculated by an absolute value circuit 1, and the contour emphasis coefficients stored as the LUT are read out. These coefficients are multiplied to a first vertical contour signal 12 formed from 1H and 2H delayed brightness signals, to which the coefficients are multiplied in a multiplier 3, in a multiplier 6 and a second contour emphasis signal 9 is generated. Thus, the desired picture quality can be obtained corresponding to the source or the pattern to be displayed by using the optimum coefficient corresponding to the state or pattern of this contour.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical contour emphasizing method for emphasizing the contour of a display image of a television or the like in the vertical direction in accordance with a picture to be displayed.

[0002]

2. Description of the Related Art Vertical contour enhancement is performed to sharpen the contour of a character or an object in the vertical direction. FIG. 3 is a circuit block diagram for implementing a conventional vertical contour enhancement method. Reference numeral 30 is an input luminance signal, and 32 is a line memory for storing data for one scanning line. 33 is a multiplier for multiplying the coefficient (a or b). A multiplier 34 multiplies a constant contour enhancement coefficient (k). The input luminance signal 30 is, as it is, a signal which is multiplied by a coefficient a by a multiplier 33, a signal which is delayed by one horizontal scanning time by a line memory 32 and is multiplied by a coefficient b by a multiplier 33, and a signal which is further delayed by one horizontal scanning time by a coefficient a. And the above three types of signals are synchronized and added pixel by pixel to obtain a first vertical contour enhancement signal. This first vertical contour emphasis signal is multiplied by a predetermined contour emphasis coefficient (k) to obtain a second vertical contour emphasis signal, and then the second vertical contour emphasis signal is set to 1
By adding to the luminance signal delayed by the horizontal scanning time, the luminance signal 35 subjected to the vertical contour enhancement processing is obtained. FIG. 4 is a diagram showing an image signal corresponding to conventional vertical edge enhancement of an image. The figure (a) shows a state in which a rectangular object 41 brighter than the peripheral portion is displayed in the central portion of the display screen 40. The change in luminance when the screen in this state is cut along the line AA ′ is shown in FIG. 46 is a luminance signal waveform of the vertical contour portion. FIG. 11B shows the screen after vertical contour enhancement processing on the screen of FIG. Reference numeral 45 is an emphasized vertical contour line.
The change in luminance when the screen in this state is cut along the line BB ′ 43 is shown in FIG. Reference numeral 47 is an emphasized signal waveform added to the contour luminance signal. However, according to the conventional vertical contour emphasis method, the obtained first vertical contour emphasis signal is multiplied by a constant contour emphasis coefficient (k) to obtain the second vertical contour emphasis signal. Therefore, it did not have the function of supplying the optimum coefficient.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and detects the state of the contour, selects the optimum value of the contour enhancement coefficient for each pixel based on the state, and enhances the contour. It is an object of the present invention to provide a vertical contour emphasis method that obtains a vertical contour emphasis signal by calculating using a coefficient.

[0004]

In order to achieve the above object, an input luminance signal, a luminance signal delayed by one horizontal scanning period and a luminance signal delayed by two horizontal scanning periods are generated and each of them is generated. A means for generating a first vertical contour emphasis signal by calculating the brightness signal for each pixel after synchronizing the brightness signal after multiplying the coefficient, and a brightness signal delayed by one horizontal scanning period from the input brightness signal. Vertical edge detecting means for detecting the degree of change in the brightness of the contour, an absolute value circuit for calculating an absolute value for the degree of change in the brightness of the detected contour, and outputting the contour emphasis coefficient stored based on the absolute value. Memory, a multiplier for multiplying the first vertical contour enhancement signal by a contour enhancement coefficient obtained from the memory to generate a second vertical contour enhancement signal, and a luminance delayed by the one horizontal scanning period. No. and comprising a second calculates the vertical contour enhancement signal adder for generating a vertical contour enhancement luminance signal.

[0005]

With the above construction, the contour enhancement coefficient is stored in the memory in advance as a lookup table, and the look-up table is referred to according to the degree of change in the brightness of the contour to find the optimum contour enhancement coefficient. And the vertical edge emphasis signal that matches the pattern is generated by performing calculation using the edge emphasis coefficient.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vertical contour emphasizing method according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a circuit block diagram for implementing a vertical contour enhancement method according to the present invention. Reference numeral 1 is an absolute value circuit for calculating an absolute value 8 for the detected degree of change in the brightness of the contour. 2 is 1 of the input luminance signal 10
It is a line memory that stores data for horizontal scanning and delays the luminance signal 10. Reference numeral 3 is a multiplier for multiplying the luminance signal by a predetermined coefficient. An adder 4 adds the input luminance signal 10 and the luminance signal 7 delayed by one horizontal scanning period.
Reference numeral 5 is a ROM that stores the contour enhancement coefficient 13 as a lookup table. Reference numeral 6 is a multiplier for multiplying the first vertical contour emphasis signal 12 by the contour emphasis coefficient 13 obtained from the memory to generate the second vertical contour emphasis signal 9. Reference numeral 11 denotes a vertical contour emphasized luminance signal obtained by adding the luminance signal 7 delayed by the one horizontal scanning period and the second vertical contour emphasized signal 9.

The operation of the vertical contour enhancement method according to the present invention will be described. FIG. 2 shows RO of the vertical contour enhancement method according to the present invention.
7 is a graph showing the characteristics of the contour emphasis coefficient stored in M. 20 is a state in which the edge signal (the degree of change in the brightness of the contour) is small and large, the contour emphasis coefficient is reduced,
This is a characteristic in which the edge enhancement coefficient is smoothly increased to a convex shape when the edge signal is in a medium level. Reference numeral 21 reduces the contour enhancement coefficient with a constant gradient when the edge signal is small, sets the contour enhancement coefficient to a small constant value when the edge signal is medium, and keeps the contour enhancement coefficient constant when the edge signal is large. It is a polygonal line characteristic that increases with a gradient. 22 is a polygonal line characteristic in which the contour enhancement coefficient is reduced with a constant gradient when the edge signal is small, and the contour enhancement coefficient is small and constant when the edge signal is medium and large. 23 is a state in which the edge signal is small and medium, the contour enhancement coefficient is a small constant value, and the edge signal is large,
This is a polygonal line characteristic in which the contour enhancement coefficient is increased at a constant gradient above the constant value. In advance, an edge enhancement coefficient as shown in FIG. 2 is created in a look-up table referred to by an edge signal and stored in the ROM 5, an edge signal is obtained as an output of the adder 4, and then the edge is calculated by the absolute value circuit 1. The absolute value 8 of the signal is generated, and the contour emphasis coefficient 13 is obtained by referring to the absolute value 8 for each pixel. The first vertical contour emphasis signal 12 is multiplied by the multiplier 6 using the contour emphasis coefficient 13 to form the second vertical contour emphasis signal 9. The luminance signal 7 delayed by one horizontal scanning period and the second vertical contour emphasis signal 9 are added to generate a luminance signal 11 after vertical contour emphasis processing. ROM5
It is also possible to store various characteristics of the contour emphasis coefficient and switch the characteristics depending on the source to be displayed.

[0008]

As described above, the present invention detects vertical contours by detecting the contour state, selecting the optimum contour enhancement coefficient for each pixel based on the state, and calculating using the contour enhancement coefficient. A vertical contour enhancement method for obtaining an enhancement signal is provided. Therefore, it is possible to obtain a desired image quality according to the source and the pattern to be displayed.

[Brief description of drawings]

FIG. 1 is a circuit block diagram for implementing a vertical contour enhancement method according to the present invention.

FIG. 2 is a graph showing a characteristic of a contour enhancement coefficient stored in a ROM of the vertical contour enhancement method according to the present invention.

FIG. 3 is a circuit block diagram for implementing a conventional vertical contour enhancement method.

FIG. 4 is a diagram showing an image signal corresponding to vertical edge enhancement of a conventional image.

[Explanation of symbols]

 1 Absolute value circuit 2 Line memory 3 Multiplier 4 Adder 5 ROM 6 Multiplier 7 1 Luminance signal delayed by horizontal scanning period 8 Absolute value 9 Second vertical contour enhancement signal 10 Input luminance signal 11 Luminance after vertical contour enhancement Signal 12 First vertical contour emphasis signal 13 Contour emphasis coefficient 20 Characteristic for increasing convex shape 21 Polygonal line characteristic for increasing 22 Polygonal line characteristic for making a constant value 23 Polyline characteristic for increasing a constant value 30 Input luminance signal 32 Line memory 33 Multiplying Unit 34 Multiplier by multiplying the contour enhancement coefficient (k) 35 Luminance signal subjected to vertical contour enhancement processing 40 Display screen 41 Square object 42 AA 'line 43 BB' line 45 Enhanced vertical contour line 46 Vertical contour portion Luminance signal 47 Enhanced signal waveform

Claims (3)

[Claims] 1. A pixel is generated by generating an input luminance signal, a luminance signal delayed by one horizontal scanning period and a luminance signal delayed by two horizontal scanning periods, and multiplying each luminance signal by a coefficient and then synchronizing the pixels. Means for calculating each luminance signal for each to generate a first vertical contour emphasizing signal; and a vertical edge for computing the luminance signal delayed by one horizontal scanning period from the input luminance signal and detecting the degree of contour luminance change. Detecting means, an absolute value circuit for calculating an absolute value with respect to the degree of brightness change of the detected contour, a memory for outputting the contour emphasis coefficient stored based on the absolute value, and the first vertical contour emphasis signal , A multiplier for multiplying the contour enhancement coefficient obtained from the memory to generate a second vertical contour enhancement signal, a brightness signal delayed by the one horizontal scanning period, and a second vertical contour enhancement signal to calculate a vertical wheel. It is characterized by comprising an adder that generates a contour-enhanced luminance signal, and that changes the contour enhancement coefficient for generating the second vertical contour enhancement signal for each pixel according to the degree of change in the brightness of the detected vertical contour. Vertical contour enhancement method. 2. The vertical contour emphasizing method according to claim 1, wherein the contour emphasizing coefficient for generating the second vertical contour emphasizing signal is stored in the ROM as a look-up table in correspondence with the degree of change in luminance of the vertical contour. 3. A plurality of types of the lookup tables R
The vertical contour enhancement method according to claim 2, wherein the method is stored in the OM.