JP2001292341A - Contour enhancement method and digital broadcast receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a contour enhancement method that does not enhance notches of a tilted edge and to provide a digital broadcast receiver that conducts video conversion processing and image quality correction processing optimum to respective planes before synthesizing the planes. SOLUTION: The digital broadcast receiver applies optimum video conversion processing and optimum image quality correction processing to four planes; a moving picture plane, a still picture plane, a character graphic plane, and a caption plane separately outputted when a digital broadcast signal is decoded and the decoded signal is converted into a video signal, synthesizes the processed planes and provides an output of the synthesized planes. Furthermore, the image quality correction processing detects a tilted edge and conducts contour enhancement by adding the difference signal between the luminance signal of a target pixel and a means value of the luminance signals of eight pixels except the target pixel resident in an area of 3 longitudinal pixels × 3 lateral pixels in the vicinity of the target pixel to the luminance signal of the target pixel while suppressing the enhancement of the tilted edge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for enhancing a contour of an image signal such as a television signal by two-dimensional signal processing, and a satellite provided with an image quality improving function such as a contour enhancing function and a progressive scan converting function. The present invention relates to a digital broadcast receiving device and a terrestrial digital broadcast receiving device.

[0002]

2. Description of the Related Art In recent years, regarding television broadcasting systems,
Regardless of terrestrial broadcasting and satellite broadcasting, conversion from the conventional analog system to the digital system is progressing in various countries around the world.
In Japan, a test broadcast is scheduled to begin in September 2000, and a main broadcast by the BS-4 late starter is scheduled to begin in December of the same year. High-definition television broadcasting is the main feature of BS digital broadcasting. And the beginning of data broadcasting. With respect to data broadcasting, it is determined by standards that BS digital broadcasting is transmitted by being divided into a plurality of video planes, that is, divided into four planes of a moving image plane, a still image plane, a character graphic plane, and a subtitle plane. .

[0003] The Data Broadcasting Coding System and Transmission System in Digital Broadcasting, published by the Radio Industry Association (standard, ARI
According to BSTD-B24, page 19), a configuration as shown in FIG. 14 is shown as the video signal processing of the BS digital broadcast receiver. The configuration and operation will be described with reference to FIG. The output P1 of the moving picture plane 101 and the output P2 of the still picture plane 102 are the moving picture / still picture switching plane 1
Based on the 1-bit output P3 of 03, the selector 106 switches and synthesizes and outputs a synthesized image P4.

Next, the video output P5 of the character / graphic plane 104 is α-blended with the composite video P4 using the 8-bit alpha value P6 output from the character / graphic plane 104 to obtain a composite video P7. Also, the subtitle plane 10
5 is converted into a table by a CLUT (color look-up table) 109, and a video output P9 is an 8-bit alpha value P1 output from the CLUT 109.
0, α is blended with the composite video P7, and the composite video is output to the composite video output terminal P11. The multiplication counts α1 and α2 in FIG. 14 are not the 8-bit values themselves but 255
Is normalized from 0 to 1.

[0005] As described above, in the BS digital broadcast receiver, separately transmitted planes are switched according to the control signal, and the planes to be displayed are obtained by combining the planes. In FIG. 14, the display of the format of each data is omitted. Although not shown, when the moving picture plane is in the 1080i format, the character / graphic plane signal 104 of 540 pixels in length and 960 pixels in width is provided before the third image quality correction unit or in order to match the display of 1080 pixels in length × 1920 pixels in width. Later, the caption plane signal 105 of 540 pixels vertically by 960 pixels horizontally is twice horizontally and vertically before or after the fourth image quality correction unit.

Since data broadcasting often displays information such as characters and figures, digital broadcasting receivers have a greater role as so-called information displays, and there is a demand for making it easier to see characters and figures clearly. Expected to be higher. On the other hand, not only when displaying characters and figures, but also various methods for enhancing a contour to give a clear feeling have been proposed and put to practical use. FIG. 15 shows, as an example, Japanese Patent Application Laid-Open No. 11-2894.
76 shows a configuration diagram of an outline emphasis circuit disclosed in 76.

The configuration and operation will be described with reference to FIG. Input signal 121, first line memory 12
2 and the output of the second line memory 123, a vertical contour component 125 is extracted by the vertical contour component detection unit 124, and the horizontal contour component is detected by the horizontal contour component detection unit 128 from the output of the first line memory 122. Extract component 129. The vertical contour component 125 and the horizontal contour component 129 are multiplied by a gain V126 and a gain H130, respectively, and then added by an adder 132. The added contour component is processed to an optimum value by the coring circuit 133 and the gain G134, and the contour component 136 is added to the original signal.
This is to obtain a signal 138 with the edge emphasized.

[0008]

However, in the configuration of the conventional digital broadcast receiver, the decoded video signal of each plane is immediately synthesized, so that the optimum video conversion processing and image quality correction processing are performed for each plane. There is a problem that can not be. For example, block noise and mosquito noise called MPEG noise are generated in a moving image plane. However, if these noises are not removed before the synthesis, a problem such as deterioration of the definition of an image other than the moving image plane occurs. The same applies to still image planes.
If noise removal is not performed prior to synthesis for noise peculiar to JPEG, inconveniences such as deterioration of the definition of images other than the still image plane occur.

[0009] For both the character graphic and the subtitle planes, processing such as contour enhancement is effective to improve readability. However, in contrast to contour enhancement performed on moving images and still images, parameters such as gain are changed. Have shown good results from visual experiments.

When receiving a data broadcast, if the moving picture plane is an interlaced scanning signal, there is no problem in displaying the image on an interlaced scanning type display. When converting into a scanning signal, a motion detection error may occur at a boundary between a moving image portion and a still image portion, and noise or flicker may occur at the boundary portion.

For example, when a character / graphic plane is α-blended 50% to 50% on a moving image plane,
Because the moving image part is determined to be a still image, jaggies occur by performing inter-field interpolation, and conversely, a character figure that is stationary is determined to be a moving image, and the resolution is reduced by intra-field interpolation. Sometimes.

If the video source of the moving picture plane is a pan or zoom scene, it is better to perform arithmetic processing only on the moving picture plane in order to increase the detection accuracy when detecting a pan or zoom scene. In addition, it is troublesome to perform the separation by referring to the signal of the moving image / still image switching plane and to perform the calculation only with the moving image plane. Similarly, when the video source of the video plane is a telecine-converted one, when detecting the telecine mode, it is better to perform the arithmetic processing only on the video plane in order to increase the detection accuracy. There is a trouble such that it is necessary to perform the division by referring to the signal of the still image switching plane and to perform the operation only with the moving image plane.

Further, the oblique contour is double-corrected in the horizontal and vertical directions, and there is a problem in that jaggies occurring in the oblique outline are emphasized. In addition, in order to suppress the jagged edge of the oblique edge generated in this way, there is an inconvenience that the gain V of the vertical contour component and the gain H of the horizontal contour component must be separately controlled. There is a problem that it is inevitable that the degree of contour emphasis changes due to.

The present invention has been made in view of the above-mentioned problems of the prior art, and therefore, a contour emphasizing method that does not emphasize jaggies of oblique edges, and an optimal image conversion process and image quality correcting process before combining each plane. It is an object of the present invention to provide a digital broadcast receiving apparatus configured to perform the following.

[0015]

According to a first aspect of the present invention, there is provided a contour emphasizing method for removing a target pixel from a luminance signal of a target pixel and a region of three pixels vertically and three pixels horizontally adjacent to the target pixel. A method is used in which a difference signal from an average value of luminance signals of eight pixels or nine pixels including the target pixel is added to the luminance signal of the target pixel.

According to a second aspect of the present invention, when the difference signal is added to the target pixel, all or one of a coring process, a limiter process, and a gain adjustment process is performed on the difference signal. Are performed in combination.

According to a third aspect of the present invention, when the difference signal is added to the target pixel, the gain of the gain adjustment processing is increased only when the difference signal has a negative value. .

A contour emphasizing method according to a fourth aspect of the present invention includes a diagonal edge extracting means for recognizing and extracting a diagonal edge, and does not perform outline emphasis when a target pixel is a part of the diagonal edge. Alternatively, the gain of contour enhancement is reduced.

According to a fifth aspect of the present invention, in the contour emphasizing method, the diagonal edge extracting means includes three vertical pixels in the vicinity of the pixel of interest.
Eight pixels that do not include the pixel of interest in the region of three horizontal pixels are 2
It is divided into two regions each having four pixels, and it is recognized whether or not the edge is a diagonal edge based on the difference signal of the average luminance of the two regions.

According to a sixth aspect of the present invention, in the contour emphasizing method, the diagonal edge extracting means includes three vertical pixels × near the target pixel.
Eight pixels that do not include the pixel of interest in the region of three horizontal pixels are 2
It is divided into two regions of four pixels each, and it is recognized whether or not the edge is an oblique edge based on a difference signal of average luminance of the two regions and a difference signal of right and left or upper and lower neighboring pixels of the target pixel. Things.

A contour emphasizing method according to a seventh aspect of the present invention is performed for each of RGB using each of RGB color signals as a luminance signal of the target pixel.

The digital broadcast receiving apparatus according to the invention of claim 8 selects a digital television signal by a digital tuner unit, and decodes encoded data of the selected digital television signal by a decode unit. In a digital broadcast receiving apparatus for converting a video signal into a video signal, video decoding, video, still image, text and graphics planes and subtitle planes, which are separately output from the decoding unit, are optimally converted to video signals. It is provided with video signal processing means for combining and outputting after performing image quality correction processing.

According to a ninth aspect of the present invention, in the digital broadcast receiving apparatus, the video signal processing unit includes an edge enhancement unit using the edge enhancement method according to any one of the first to seventh aspects in the image quality correction processing.

According to a tenth aspect of the present invention, in the digital broadcast receiving apparatus, when the moving picture plane is an interlaced scanning signal in the video conversion processing, the video signal processing means uses a motion detection signal before synthesizing the progressive scanning signal. Is provided.

In the digital broadcast receiving apparatus according to an eleventh aspect of the present invention, the progressive scan conversion means determines a moving image portion and a still image portion for each pixel using a frame difference or a field difference in the video conversion process, and performs the progressive scan conversion. A pan / zoom detecting means for detecting a pan scene in which the entire screen moves in the same direction or a zoom scene in which the image is enlarged or reduced around the center of the screen, and a jump of 60 frames per second from a movie film of 24 seconds. It has both or one of telecine detecting means for detecting a telecine mode converted into a scanning signal.

According to a twelfth aspect of the present invention, in the digital broadcast receiving apparatus, the video signal processing means reduces MPEG noise such as block noise and mosquito noise before synthesizing the moving picture plane in the image quality correction processing.
PEG noise removal means is provided.

[0027]

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram of the digital broadcast receiving apparatus according to the first embodiment of the present invention. In FIG. 1, reference numeral 10 denotes a digital television signal, 11 denotes a digital tuner for selecting a desired channel from the input digital television signal, 12 denotes a decoder for decoding encoded data of the selected channel, 13 Is a plurality of video planes output from the decoder unit 12, namely, a moving image plane, a still image plane, a moving image / still image switching plane, a character / graphic plane, and a subtitle plane;
A video signal processing unit 14 that receives the synchronization signal and the control signal, and combines and outputs based on the control signal is a combined video output signal.

The video signal processing section 13 in FIG. 1 will be described in more detail with reference to FIG. In FIG. 2, the same parts as those in FIG. 14 are denoted by the same reference numerals, and detailed description is omitted. Reference numeral 21 denotes a video conversion unit that converts a signal P1 of the moving image plane 101 into a progressive scan signal when the display P is a progressive scan type and the display is a progressive scan type.
Is a progressive scanning signal or an interlaced scanning signal.

Reference numeral 22 denotes a scaling unit for enlarging or reducing an input video signal to a designated size, P22 a scaled video plane signal, and 23 a video signal for optimally correcting the image quality of the video plane signal. 1 image quality correction unit, 24 is a second image quality correction unit that performs optimal image quality correction on a still image plane signal, and 25 is third image quality correction unit that performs optimal image quality correction on a character / graphic plane signal. , 26 are a fourth image quality correction unit for performing optimal image quality correction on the signal of the subtitle plane, P23 is a video signal of a moving image plane whose image quality has been corrected, P24 is a video signal of a still image plane whose image quality has been corrected, and P25 is a video signal of a still image plane. P26 is a video signal of a subtitle plane whose image quality has been corrected. Although not shown, a synchronization signal and a control signal output from the decoder are input to each processing unit.

Next, the first image quality correction unit 23 in FIG.
The second image quality correction unit 24, the third image quality correction unit 25, and the fourth image quality correction unit 26 will be described in more detail with reference to FIGS. FIG. 3 is a circuit diagram showing an example of the processing performed by the first to fourth image quality correction units in a case where an outline enhancement process is performed.
Are input terminals of video signals for each video plane, 41, 42
Is a line memory for delaying by one horizontal line, and 31 to 39 are delay elements for delaying by one pixel clock, respectively. The position of the target pixel A and the eight pixels d0 to d7 near A shown in FIG. The signal corresponding to the position can be extracted from A and d0 to d7 shown in FIG.

Reference numeral 43 denotes eight neighbors d0 to d7 of the eight neighbors of the target pixel A.
An average value calculating unit that calculates the average value of the pixels or the nine pixels to which the pixel of interest A is further added; 44 is a difference unit that subtracts the average value obtained by the average value calculating unit 43 from the value of the pixel of interest A;
Reference numeral 5 denotes a coring unit that performs coring processing on the output signal of the differentiator 44 with a preset value, and reference numeral 46 denotes a limiter unit 47 that limits the output signal of the coring unit 44 at a predetermined level. A gain section for generating a set gain value, and a limiter section 48
Is a multiplier for multiplying the output signal of the gain unit 47 by the gain signal output from the gain unit 47, 49 is an output signal of the multiplier 48, which is an enhancement component for the target pixel A, and 50 is an addition for adding the enhancement component 49 to the value of the target pixel A. Reference numeral 51 denotes an output terminal of a signal whose image quality has been corrected.

FIG. 5 is a diagram for explaining the principle of the outline emphasizing process described with reference to FIGS. 3 and 4 for reference. In FIG. 5A, when the horizontal axis indicates the average value of eight pixels in the vicinity of the target pixel A and the vertical axis indicates the value of the target pixel A, appropriate coring values, limiter values, and gain values are set. FIG. 7 illustrates regions having different characteristics of the emphasized component when the above-described processing is performed. The values that can be taken on both the horizontal axis and the vertical axis are from 0 to 255 when the video signal is 8 bits.
, And is plotted at any point within this square frame for any signal.

In the figure, a region R is a region where the emphasis component 49 is zero, a region Q and a region S are regions where the value of the emphasis component 49 changes according to the difference value, a region P and a region T depend on the difference value. Area where the value of the emphasis component 49 is constant.
Further, regions P and Q are regions that are emphasized so as to increase luminance, and regions S and T are regions that are emphasized so as to decrease luminance. FIG. 5B shows the point M shown in FIG.
And the straight line connecting the point N is plotted on the horizontal axis, and the vertical axis is drawn on the straight line M−
This is a profile obtained by taking a difference value between the average value of eight pixels near the target pixel A and the value of the target pixel A at each point on N.

FIG. 5C shows a profile after the above-mentioned difference value is subjected to the coring process. The range in which the difference value is set to zero changes depending on the setting of the coring value. FIG. 5 (d)
Is the value after the limiter process is performed on the profile of FIG. 5C, and the maximum value and the minimum value change depending on the setting of the limit level. FIG. 5E shows a state after the gain processing has been performed on the profile of FIG. 5D.

Although FIGS. 5B to 5E show profiles between M and N as representatives, a straight line M to N is shown in FIG.
The profile on the line that has been translated in FIG. 5A also has an average value of 8 pixels near the center, that is, the pixel A of interest only by cutting off both ends outside the range of the square in FIG. A similar profile is obtained centering on a line where the difference value of the value of the target pixel A is equal.

The emphasis component shown in the graph is an example in which coring processing, limiter processing, and gain processing are performed in this order, but the order is not limited to this example. If any of the processes is omitted, the profile will have a different shape.

Next, in the profile of the emphasized component shown in FIG. 5, the emphasis for increasing the luminance and the emphasis for decreasing the luminance are at the same level, and the graph is point-symmetric with respect to the origin in the graph. The gain can be adjusted according to the display device to be displayed. For example, in a CRT, a high-luminance pixel is blurred due to an increase in beam spot diameter called blooming as the beam current increases due to enhancement. May be. Therefore, FIG.
As shown in (a), it has been found by visual experiments that when the emphasis for lowering the luminance is suppressed and the emphasis for lowering the luminance is increased, black is tightened and looks clearer. Further, when an area where the enhancement is effective is grasped in advance by a visual experiment, it is possible to selectively set the enhancement area as shown in FIG. 6B.

(Embodiment 2) Hereinafter, a second embodiment of the present invention will be described with reference to FIGS. FIG. 7 shows the first to fourth embodiments according to the second embodiment of the present invention.
As an example of the processing of the image quality correction unit, a circuit configuration diagram in the case where an oblique edge detection unit is provided to perform contour enhancement processing, the same parts as those in FIG. 3 are denoted by the same reference numerals, and detailed description will be omitted. In FIG. 7, reference numeral 52 denotes an oblique edge detection unit, and reference numeral 53 denotes an oblique edge detection signal, which controls the gain unit 47.

Next, the configuration and operation will be described in detail with reference to FIGS. FIG. 8 is a diagram showing a part of the circuit configuration of the oblique edge detection unit 52,
FIG. 9B shows a P-region average value calculator for calculating the average value of the P region, 62 is a Q-region average value calculator for calculating the average value of the Q region also shown in FIG. 9B, and 63 to 66 are difference calculators. , 6
7 is a first set value, 69 is a second set value, 71 to 74 are comparators, 75 and 76 are AND operation elements, 77 is an OR operation element, and 78 is an oblique edge detection flag output terminal.

The P-region average value calculation unit 61 has d0, d1,
The luminance values of the four pixels d2 and d3 are input to calculate an average value, and the Q region average value calculation unit 62 outputs d4, d5, d
The luminance values of the four pixels 6 and d7 are input, and the average value is obtained. In the differentiator 63, the output of the Q-region average value calculation unit 62 is subtracted from the output of the P-region average value calculation unit 61, and the difference is compared with the first set value 67 in the comparator 71. Is output, and if smaller, Lo
Output w.

In the differentiator 64, the output of the P-region average value calculator 61 is subtracted from the output of the Q-region average value calculator 62,
The comparator 72 compares the first set value 67 with the first set value 67, and outputs Hi when it is larger than the first set value 67, and outputs L when it is smaller than the first set value 67.
ow is output. The difference unit 65 calculates d4 from the luminance value of d3.
Is subtracted from the second set value 69 in the comparator 73, and if it is larger than the second set value 69, Hi
Is output, and if it is smaller, Low is output. In the differentiator 66, the luminance value of d3 is subtracted from the luminance value of d4.

The comparator 74 compares the second set value 69 with the second set value 69, and outputs Hi when it is larger than the second set value 69.
If it is smaller, Low is output. Based on the above output values,
If a logical operation is performed and it is determined that the edge is an oblique edge, Hi is output to the oblique edge detection flag 78.

In FIG. 7, when the oblique edge detection flag output from the oblique edge detection section 52 is input to the gain section 47, the gain is reduced to zero or reduced to suppress the edge enhancement of the oblique edge. Can be.

FIG. 9 is a diagram for making it easier to understand the oblique edge detection process. FIG. 9A shows the pixel of interest A in the area of 3 pixels vertically × 3 pixels around the pixel of interest A.
FIG. 9 is a diagram showing the positions of eight pixels d0 to d7 in the vicinity of FIG.
(B) to (e) each show an area of 3 pixels in the vertical direction and 3 pixels in the horizontal direction centering on the target pixel A, and a method of detecting a diagonal edge will be described in further detail with reference to FIG.

For example, in FIG.
Is divided into two regions of P and Q, each of which consists of four pixels, the average values p and q of the regions of P and Q
Can be obtained by the following equations, respectively, and p = (d0 + d
1 + d2 + d3) / 4, q = (d4 + d5 + d6 + d
7) / 4. The condition under which the oblique edge can be detected using p, q, d3, and d4 is as follows.
1, if the second set value 69 is th2, p−q> th
1 and d3-d4> th2, and qp> th
1 and d4−d3> th2.

9 (c), 9 (d) and 9 (e) are the same, and the description is omitted, but the regions R, S, T,
The average values of the region U, the region V, and the region W are r,
Assuming that s, t, u, v, and w are satisfied, as shown in the table of FIG. 10, when the condition marked with a white circle is satisfied, it is determined that the edge is an oblique edge.

As is clear from the description of FIG.
The oblique edge detection circuit of FIG. 8 shows only the angle in one direction shown in FIG. 9B, and when the region R, the region S, d3 and d4 of FIG.
When the region T, the region U, d1, and d6 in FIG. 9D are referred to, and the region V, the region W, d1, and d6 in FIG. 9E are referred to, the same circuit configuration can be realized.
In (b) and (c), the angle with respect to the horizontal line is 45.
9 (d) and 9 (e), an oblique edge having an angle of 45 ° or more with respect to the horizontal line can be detected.

FIG. 11 shows an example of an image in which a diagonal edge is detected. One square surrounded by a dotted line represents one pixel.
For example, the pixels A, B, C, D, E, F, G, H, and the like are determined to be oblique edges, and contour emphasis can be suppressed. When the pixel A, the pixel B, the pixel C, and the pixel D are the target pixel, the logical product operator 76 of FIG. 8 becomes Hi, and when the pixel E, the pixel F, the pixel G, and the pixel H are the target pixel, the logic of FIG. H in product operator 75
i.

(Embodiment 3) Hereinafter, a third embodiment of the present invention will be described with reference to FIGS. FIG. 12 shows an example of the third embodiment of the present invention.
Video signal processing unit 1 including MPEG noise removing unit 81
3, the same parts as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted. The processing means for removing the MPEG noise is disclosed in detail in JP-A-10-229546 or JP-A-11-46362, and a detailed description thereof will be omitted in this specification. Further, the processing means of the MPEG noise removal is not limited to the method and means of the prior application, but may be any means for removing or reducing the MPEG noise.

FIG. 13 is a block diagram of the video converter 21 shown in FIG. 12 as an example of the third embodiment of the present invention.
0 is a video input terminal of a moving picture plane, 91 is a telecine detecting section, S1 is a signal line 92 indicating that the telecine mode is detected in the telecine detecting section 91, a pan / zoom detecting section, and S2 is a pan / zoom detecting section 92. , A signal line indicating that a pan or zoom scene has been detected, 93
Is a progressive scan converter, and 94 is a sequentially scanned video signal output terminal.

The pan is a signal for moving the entire screen uniformly in the same direction, and the zoom is a signal for enlarging or reducing the center of the screen. Here, the telecine detecting section 91 is disclosed in detail in JP-A-11-261972 or JP-A-11-261927, and the pan / zoom detecting section 92 is disclosed in detail in JP-A-5-153470. Detailed description is omitted in this specification.

Further, the progressive scan conversion unit 93 is disclosed in
As disclosed in US Pat. No. 27589, the process of detecting motion for each pixel, switching between inter-field interpolation and intra-field interpolation, and converting interlaced scanning signals into sequential scanning signals is the same. Although the detailed description is omitted in this specification since it is disclosed in detail, the gist of the present invention is that when the telecine mode detection signal S1 is output in the progressive scan conversion unit 93,
When a sequential scan conversion is performed by inter-field interpolation as shown in JP-A-11-261972 and output to a video signal output terminal 94, the telecine mode detection signal S1 is not output, and the pan or zoom detection signal S2 is output. , Perform sequential scan conversion by inter-field interpolation according to the pan or zoom signal, and when neither the telecine mode detection signal S1 nor the pan or zoom detection signal S2 is output,
As disclosed in Japanese Patent Application Laid-Open No. 1-227589, a motion is detected for each pixel, inter-field interpolation and intra-field interpolation are switched, and the interlaced scanning signal is converted into a sequential scanning signal. Output.

The coring processing, limiter processing, and gain processing in the first embodiment are not limited to this order, nor are all of them necessary.

In the first and second embodiments, the outline emphasis processing has been described as an example of the processing of the first to fourth image quality correction units. However, the present invention is not limited to this. Any processing may be used as long as the processing improves. Further, the outline emphasis processing is not limited to the method described above, and any method may be used as long as it is optimized for each video plane or each display device.

In the first to third embodiments, the processing is performed using the luminance signal of the pixel. However, the present invention is not limited to this, and the processing may be performed for each of the RGB color signals.

In the first to third embodiments, the configuration and operation have been described by taking the BS digital broadcasting system as an example.
The present invention is not limited to this system, and can be applied to various digital broadcasting systems or various analog broadcasting systems.

Although the hardware configuration has been described in the first to third embodiments, similar effects can be obtained with a software configuration.

Although the first to third embodiments have been described using a part of the CRT as an example, the target display device is not limited to this, but may be any type of device such as a plasma display panel or a liquid crystal panel. It is applicable to a receiving device using a video display device, and further,
So-called STB (Set Top Box),
The present invention is also applicable to a device that receives a broadcast and outputs a video signal.

[0059]

As described above, according to the present invention, since various video conversion processes and image quality correction processes are performed on each video plane of a digital television signal before combining them, the present invention is not affected by non-target video planes. Therefore, for a moving image, various types of correction processing that are optimal for the moving image can be performed.For example, in the case of an interlaced scanning signal, motion detection necessary for sequential scan conversion, detection of a telecine mode, panning and zooming scenes can be performed. Detection can be performed with high accuracy, and a motion detection error at a boundary portion when the images are synthesized can be prevented, and a beautiful image having no noise at the boundaries can be synthesized. Further, it is possible to provide a digital broadcast receiving apparatus capable of performing processing such as enhancing the legibility of characters by strengthening the outline emphasis for character images.

Further, three pixels vertically × 3 pixels horizontally near the pixel of interest.
Since contour enhancement processing is performed by two-dimensional signal processing of pixels, jaggies of oblique edges generated by performing enhancement processing twice in the vertical and horizontal directions as in the related art can be suppressed. Furthermore, by detecting a diagonal edge and suppressing the contour emphasis at the diagonal edge portion, it is possible to provide a contour emphasizing method that enables beautiful contour emphasis without emphasizing jagged edges.

[Brief description of the drawings]

FIG. 1 is an overall block configuration diagram of a digital broadcast receiving apparatus according to first to third embodiments of the present invention.

FIG. 2 is a block diagram of a video signal processing unit according to the first embodiment of the present invention.

FIG. 3 is a circuit configuration diagram of an outline enhancement process according to the first embodiment of the present invention;

FIG. 4 is a pixel arrangement diagram according to the first embodiment of the present invention;

FIG. 5 is an explanatory diagram of an outline emphasizing operation according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram of an outline emphasis operation according to the first embodiment of the present invention.

FIG. 7 is a circuit configuration diagram of contour enhancement processing according to a second embodiment of the present invention;

FIG. 8 is a circuit configuration diagram of an oblique edge detection unit according to a second embodiment of the present invention.

FIG. 9 is an explanatory diagram of a diagonal edge detection process according to the second embodiment of the present invention.

FIG. 10 is a diagram showing conditions for determining a diagonal edge according to the second embodiment of the present invention;

FIG. 11 is a diagram illustrating an example of an oblique edge detection pixel according to the second embodiment of the present invention;

FIG. 12 is a block diagram of a video signal processing unit according to a third embodiment of the present invention.

FIG. 13 is a block diagram of a video converter according to a third embodiment of the present invention.

FIG. 14 is a block diagram of a video signal processing of a conventional digital broadcast receiving apparatus.

FIG. 15 is a block diagram of a conventional edge enhancement process.

[Explanation of symbols]

 Reference Signs List 10 digital television signal 11 digital tuner 12 decoder unit 13 video signal processing unit 14 composite video output signal 21 video conversion unit 22 scaling unit 23 first image quality correction unit 24 second image quality correction unit 25 third image quality correction unit 26 fourth image quality Correction units 31 to 39 1 pixel clock delay element 40 Video input terminal 41, 42 Line memory 43 Average calculation unit 44 Difference unit 45 Coring unit 46 Limiter unit 47 Gain unit 48 Multiplier 49 Enhanced component 50 Adder 51 Enhanced video output Terminal 52 Oblique edge detection section 53 Oblique edge detection signal 61 P area average value calculation section 62 Q area average value calculation section 63 to 66 Differentiator 67 First set value 69 Second set value 71 to 74 Comparator 75, 76 AND operator 77 OR operator 78 Oblique edge detection flag output terminal 81 M EG noise removal unit 91 Telecine detection unit 92 Pan / zoom detection unit 93 Sequential scan conversion unit 101 Video plane 102 Still image plane 103 Video / still image switching plane 104 Text / graphic plane 105 Subtitle plane 106 Selector 107, 108, 110, 111 Multiplier 109 CLUT (Color Lookup Table) 122 First Line Memory 123 Second Line Memory 124 Vertical Contour Component Detector 125 Vertical Contour Component 126 Gain V 127, 131, 135 Multiplier 128 Horizontal Contour Component Detector 129 Horizontal Contour Component 130 Gain H 132,137 Adder 133 Coring unit 134 Gain G

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hiroshi Nio 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Kazuto Tanaka 1006 Kadoma Kadoma Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Yuichi Ishikawa 1006 Kadoma, Kazuma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Katsumi Terai 1006 Odaka, Kazuma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 1006, Kadoma, Kadoma, Fumonma-shi Matsushita Electric Industrial Co., Ltd. CE02 CE03 CE08 CG10 CH20 DA17 DB02 DB06 DB09 DC16 5C021 PA02 PA12 PA17 PA42 PA53 PA66 PA67 PA72 PA79 PA82 RA01 RA02 RC06 SA25 XA07 XB03 XB04 YC08 5C066 AA03 CA07 DB07 EA03 EC02 EC12 EE01 EF11 EF12 GA01 GA05 GA26 GA32 GA33 GB01 HA01 JA01 KA12 KC01 KC11 KD02 KD06 KE02 KE03 KE05 KE07 KE11 K16 KE16

Claims (12)

[Claims] 1. An outline emphasizing method for emphasizing the outline of an image signal, comprising: a luminance signal of a pixel of interest and 8 pixels excluding the pixel of interest in an area of 3 × 3 pixels near the pixel of interest; A contour emphasizing method characterized by adding a difference signal from an average value of luminance signals of nine pixels including a target pixel to the luminance signal of the target pixel. 2. The method according to claim 1, wherein when adding the difference signal to the pixel of interest, all or a combination of any of a coring process, a limiter process, and a gain adjustment process is performed on the difference signal. Item 4. The contour enhancement method according to Item 1. 3. The contour emphasizing method according to claim 2, wherein when adding the difference signal to the target pixel, the gain of the gain adjustment processing is increased only when the difference signal has a negative value. . 4. An oblique edge extracting means for recognizing and extracting an oblique edge, wherein no contour enhancement is performed or a contour enhancement gain is reduced when a target pixel is a part of the oblique edge. 4. The contour emphasizing method according to claim 1, wherein: 5. The oblique edge extracting means divides eight pixels that do not include the pixel of interest in an area of three vertical pixels by three horizontal pixels in the vicinity of the pixel of interest into two, and divides each pixel into two regions of four pixels each. 5. The contour emphasizing method according to claim 4, wherein whether or not the edge is an oblique edge is recognized based on a difference signal of the average luminance of the two regions. 6. The oblique edge extracting means divides eight pixels not including a target pixel in an area of three vertical pixels × three horizontal pixels in the vicinity of the target pixel into two, and divides each pixel into two regions of four pixels each. 5. The contour emphasizing method according to claim 4, wherein whether or not the edge is an oblique edge is recognized based on a difference signal of average luminance of the two regions and a difference signal of right and left or up and down adjacent pixels of the target pixel. 7. A RGB signal as a luminance signal of the pixel of interest.
7. The contour emphasizing method according to claim 1, wherein the processing is performed for each of RGB using the respective color signals. 8. A digital broadcast receiving apparatus for selecting a digital television signal by a digital tuner section, decoding the encoded data of the selected digital television signal by a decoding section, and converting the encoded data into a video signal. In the above, optimal video conversion processing and image quality correction processing are respectively performed on the four planes of the moving image plane, the still image plane, the character graphic plane, and the subtitle plane, which are separately output from the decoding unit, and then combined. A digital broadcast receiving device comprising a video signal processing unit for outputting. 9. The digital broadcast receiving apparatus according to claim 8, wherein said video signal processing means includes an outline emphasis means using the outline emphasis method according to claim 1 in said image quality correction processing. 10. The video signal processing means includes a progressive scan conversion means for converting to a progressive scan signal using a motion detection signal before combining when the moving picture plane is an interlaced scan signal in the video conversion processing. 9. The digital broadcast receiving device according to claim 8, wherein: 11. The progressive scanning conversion means determines a moving image portion and a still image portion for each pixel by using a frame difference or a field difference in the video conversion processing and performs sequential scanning conversion. Pan / zoom detection means for detecting a moving pan scene or a zoom scene which expands or contracts around the center of the screen, and detects a telecine mode converted from a 1/24 frame movie film into a 1/60 frame interlaced scanning signal. 11. The digital broadcast receiving apparatus according to claim 10, further comprising at least one of a telecine detecting means for performing the digital broadcasting. 12. The video signal processing means includes MPEG noise removing means for reducing MPEG noise such as block noise and mosquito noise before synthesizing the moving picture plane in the image quality correction processing. The digital broadcast receiving device according to claim 8.