CN1065396C - Screen detection system for wide screen TV - Google Patents

Abstract

A screen detection system for detecting upper and lower blanking areas in a wide screen television, comprising: a comparator for comparing the image signal with the blanking critical value, and generating a positive value signal if the image signal is greater than the blanking critical value; a synchronization circuit for separating vertical and horizontal synchronization signals from the video signal and generating a period signal after each horizontal synchronization signal; a blanking period detector for detecting the output of the comparator in each period signal and generating a blanking signal if there is no positive value signal; a display limit generator for determining the upper display limit and the lower display limit according to the distribution of the blanking signal.

Description

Screen detection system for wide screen TV

The invention relates to a screen detection system applied to a wide-screen television, in particular to a screen detection system used to detect the upper and lower blanking areas of the screen.

As 16:9 wide-screen TVs become more and more popular, compatibility issues arising from displaying 4:3 image frames of the traditional NTSC system on 16:9 wide-screen TVs have also attracted increasing attention. In the traditional 4:3 image frame, programs with a 16:9 image frame are often broadcast, such as movie programs. Please refer to FIG. 1A to FIG. 1C . FIG. 1A shows a 4:3 image frame 10 including a 16:9 image frame. The screen 10 is composed of three areas: an area 11 for displaying a 16:9 image screen, and upper and lower two blank areas (blank areas) 12 and 13, which are often used to display some information, tags or advertisements etc. A perfect circle 14 is displayed in the area 11 for comparison. FIG. 1B is a 16:9 image 15 that is flatly converted from the 4:3 image 10 shown in FIG. 1A through horizontal zoom-in using existing image display technology. In the frame 15, the regions 12 and 13 that were originally the frame 10 are preserved, but the perfect circle 14 located in the region 11 becomes severely elliptical due to horizontal enlargement. FIG. 1C is a 16:9 frame produced by another existing image display technology, which completely removes the regions 12 and 13 of the original frame 10 and only retains the region 11 . This method can truly display the region 11 on the 16:9 screen, but the upper and lower regions 12 and 13 will be cut off so that no information or images can be displayed.

The main purpose of the present invention is to provide a screen detection system applied to wide-screen TVs to flexibly remove the upper and lower blanking areas that appear in traditional 4:3 image frames without cutting any image frames or information.

The object of the present invention is achieved by providing a screen detection system for a wide-screen TV, which is used to detect the blanking area located at the upper and lower ends of an image screen in an input image signal, and the wide-screen TV includes a 16:9 The screen and a screen display system are used to display the image frame between an upper display limit and a lower display limit in the input image signal on the screen; the screen detection system includes: (a) a comparator for Comparing the image signal with a predetermined blanking threshold, if the image signal is greater than the blanking threshold, a positive signal is generated; (b) a synchronization circuit for separating vertical and horizontal synchronization signals in the image signal , and generate a periodic signal after each horizontal synchronous signal; (c) a blanking period detector, used to detect the output of the comparator in each periodic signal, if the comparator has no output in a periodic signal positive value signal output, the blanking period detector will generate a blanking signal; (d) a display limit generator, used to determine the The upper display limit and the lower display limit are determined based on the distribution of the blanking signal immediately preceding the second vertical sync signal.

In order to enable the structure, features and effects of the present invention to be further understood and recognized, this paper is described in detail in conjunction with preferred embodiments and accompanying drawings as follows:

Brief description of the drawings

FIG. 1A is a traditional 4:3 image frame;

Figure 1B is a 16:9 picture obtained by horizontally enlarging the picture in Figure 1A;

Figure 1C is a 16:9 picture produced by removing the upper and lower areas of the picture in Figure 1A;

Fig. 2 is the system block diagram of wide-screen TV and screen detection system thereof of the present invention;

Fig. 3 is the sequence diagram of Fig. 2;

Fig. 4 is the procedure used when the display limit generator in the block diagram of Fig. 2 determines the upper and lower display limits;

Figure 5 shows another procedure used by the limit generator.

Please refer to Figure 2. FIG. 2 is a system block diagram of a wide-screen TV and its screen detection system of the present invention. Figure 2 shows that the widescreen TV contains:

(1) a 16:9 screen 22;

(2) A screen display system 21 is used to display on the screen an image frame between an upper end display limit and a lower end display limit in the image signal input by the VIDEO port;

(3) A screen detection system 23 is used to detect the blanking area located at the upper and lower ends of an image screen in the image signal input by the VIDEO port and produces an upper end display limit and a lower end display limit. The screen detection system 23 includes:

(a) a comparator 24 is used for comparing this image signal with a predetermined blanking threshold value THD, if the amplitude of this image signal is higher than this blanking threshold value THD, then generate a positive value signal at the COMP port;

(b) A synchronous circuit 25 is used to separate the vertical and horizontal synchronous signals from the image signal and be separated by V. SYNC port and H. SYNC port output, the synchronization circuit 25 will generate a period signal to the PERIOD port after each horizontal sync signal;

(c) A blanking period detector 26 is used to detect the output of the comparator 24 in each period signal, if the comparator 24 has no positive signal output in a period signal, then the blanking period detector 26 A blanking signal will be generated to the BLANK port;

(d) A display limit generator 27 is used to determine the upper display limit according to the blanking signal distribution immediately after the first vertical synchronizing signal and according to the blanking signal distribution immediately before the second vertical synchronizing signal The lower end display limit is determined according to the situation.

Please refer to Figure 3. FIG. 3 is a timing diagram of the wide-screen TV shown in FIG. 2 . The image signal input from the VID-EO port in FIG. 2 includes a vertical synchronization signal 33 , a plurality of horizontal synchronization signals 34 , and a video signal 30 after each horizontal synchronization signal 34 . If a video signal 30 contains real images, the amplitude of the video signal 30 will be higher than

A predetermined blanking threshold THD (indicated by dashed lines). But if it does not contain any image, its amplitude will be lower than the blanking threshold THD. The comparator 24 will compare the image signal input by the VIDEO port with the blanking threshold THD, if the image signal is greater than the blanking threshold THD, the comparator 24 will generate a positive signal at the COMP port, such as signal 31 . Synchronization circuit 25 can separate vertical synchronous signal 33 and horizontal synchronous signal 34 from the image signal to V. The SYNC port generates the corresponding vertical sync signal 35 and in H. The SYNC port generates horizontal sync signal 36 . In addition, the synchronization circuit 25 will generate a period signal 37 after each horizontal synchronization signal 36, and the blanking period detector 26 will detect the COMP port of the comparator 24 within each period signal 37, if no positive value signal is detected If it is detected, a blanking signal 38 will be generated at its BLANK port to indicate that there is probably no image in this video signal. Certainly, if the time length of the periodic signal 37 is closer to the length of its corresponding video signal, the accuracy of this detection will be higher. The display limit generator 27 will use the output of the blanking period detector 26 and the synchronization circuit 25 to determine the upper and lower display limits for the screen display system 21 to remove the upper and lower blanking regions 12 and 13 as shown in FIG. 1A .

The function of display limit generator 27 can be accomplished with a microprocessor, which can judge and produce the upper end display limit according to the blanking signal distribution situation immediately after the first vertical sync signal, and according to the second The distribution of the blanking signal before a vertical sync signal is judged and generated to generate the lower display limit. Figures 4 and 5 show two different procedures for determining the upper and lower display limits.

FIG. 4 is a program 40 used by the display limit generator 27 in the block diagram of FIG. 2 when determining upper and lower display limits. Routine 40 counts the number of consecutive blanking signals immediately following the first vertical sync signal to generate the upper display limit, and the number of consecutive blanking signals immediately preceding the second vertical sync signal to generate The lower end shows the limit. This method can accurately identify the upper and lower blanking areas in an image frame in the image signal so that the screen display system 21 can accurately remove the upper and lower blanking areas when displaying the image signal on the screen 22 . In program 40, the number of horizontal sync signals between two vertical sync signals is denoted by H, the variable i represents the number of received horizontal sync signals, and the variable j represents the number of detected blanking signals. Procedure 40 comprises the following steps:

Step 41 waits for the first vertical sync signal;

Step 42 sets i=O; j=O;

Step 43 sets i=i+1 after receiving a horizontal synchronization signal;

Step 44 detects whether there is a blanking signal, if not then to step 46;

Step 45 sets j=j+1, and goes to step 43;

Step 46 generates an upper display limit using the comparison of j and H;

Step 47 sets j=0;

Step 48 sets i=i+1 after receiving a horizontal synchronization signal;

In step 49, if i=H, go to step 53;

Step 50 detects whether there is a blanking signal, and if so, proceeds to step 52;

Step 51 sets j=0, to step 48;

Step 52 sets j=j+1, to step 48;

Step 53 uses the comparison value of j and H to generate the lower end display limit;

Step 54 ends.

FIG. 5 shows another program 60 used by limit generator 27 . The program 60 scans the entire predetermined upper area 12 and lower area 13 to determine whether any information or images appear in any of the areas. If any information or images are present, the entire upper area 12 and lower area 13 will be displayed. However, if most of the video signals detected in the upper or lower area are blanking signals, then this area will be completely removed and not displayed. Whether there is information or an image appears in the upper or lower region is determined by the total number of blanking signals detected in that region. If the total number of blanking signals exceeds a certain predetermined ratio such as 98%, the boundary between area 11 and upper area 12 or lower area 13 in Fig. 1A will be set as the upper display limit or the lower display limit to remove the entire upper end area 12 or lower end area 13 . This method of calculating the percentage can avoid that when a small amount of noise appears in the upper or lower region, the position where the noise occurs will be mistakenly identified as the upper or lower display limit of the image. In the program 60, the predetermined upper and lower display limits are represented by TL and BL respectively, and the number of horizontal synchronous signals between two vertical synchronous signals is represented by H, and the variables t and b represent the upper and lower limits to be determined respectively. The lower end shows the limit, the variable i represents the number of horizontal synchronization signals received, and the variable j represents the number of blanking signals received. Procedure 60 comprises the following steps;

Step 61 waits for the first vertical sync signal;

Step 62 sets i=j=0; t=TL (predetermined upper display limit);

Step 63 sets i=i+1 after receiving a horizontal synchronization signal;

Step 64 detects whether there is a blanking signal, if not then to step 66;

Step 65 sets j=j+1;

In step 66, if i<TL, go to step 67;

Step 67 If (j/TL)>=98%, then go to step 69,

Step 68 sets t=0 (the top of the image frame);

Step 69 sets j=0, b=BL (predetermined lower end display limit);

Step 70 sets i=i+1 after receiving a horizontal synchronization signal;

In step 71, if i<BL, go to step 70;

Step 72 sets i=i+1 after receiving a horizontal synchronization signal;

Step 73 detects whether there is a blanking signal, if not then to step 75;

Step 74 sets j=j+1;

In step 75, if i<H, go to step 72;

In step 76, if [j/(H-BL)]>=98%, go to step 78;

Step 77 sets b=H (bottom of image frame);

Step 78 ends.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the application of the present invention shall fall within the protection scope of the patent of the present invention.

Claims (7)

1, a kind of screen detection system of panavision, be used to detect the blanking zone that is positioned at an image frame upper and lower end in the picture signal of input, this panavision includes 1: 9 screens and an on-screen display system are used for being positioned at a upper end in will the picture signal of input and show that the limit and a lower end show that the image frame between the limit is presented on this screen; This screen detection system includes:

(a) comparator is used for this picture signal relatively and a predetermined blanking critical value, if this picture signal then produces one on the occasion of signal greater than this blanking critical value;

(b) synchronous circuit is used for separating the vertical and horizontal synchronizing signal in this picture signal, and produces the one-period signal after each horizontal-drive signal;

(c) a blanking cycle detector is used for detecting the output of this comparator in each periodic signal, if this comparator does not have on the occasion of signal output among the one-period signal, then this blanking cycle detector can produce a blanking signal;

(d) one shows limit generator, is used for deciding this upper end demonstration limit and deciding this lower end to show the limit according to being next to second vertical synchronizing signal blanking signal distribution scenario before according to being next to first vertical synchronizing signal blanking signal distribution scenario afterwards.

2, screen detection system as claimed in claim 1, this demonstration limit generator are made aforesaid upper end according to the number that is next to the afterwards continuous blanking signal of first vertical synchronizing signal and are shown the limit.

3, screen detection system as claimed in claim 1, this demonstration limit generator are made aforesaid lower end according to the number that is next to the preceding continuous blanking signal of second vertical synchronizing signal and are shown the limit.

4, screen detection system as claimed in claim 1, if when being positioned at ratio that first vertical synchronizing signal and a predetermined upper end show blanking signal number and the horizontal-drive signal number of being received during this between the limit greater than a predetermined ratio, the upper end demonstration limit that this demonstrations limit generator can be scheduled to is set at the aforesaid upper end demonstration limit.

5, screen detection system as claimed in claim 4, this predetermined ratio is 98%.

6, screen detection system as claimed in claim 1, if when being positioned at ratio that a predetermined lower end shows blanking signal number and the horizontal-drive signal number of being received during this between the limit and second vertical synchronizing signal greater than a predetermined ratio, the lower end demonstration limit that this demonstrations limit generator can be scheduled to is set at the aforesaid lower end demonstration limit.

7, screen detection system as claimed in claim 6, this predetermined ratio is 98%.

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