JPH10149137A - Motion vector detecting circuit for animation picture correction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a wrong motion vector from being detected when the movement quantity of an animation picture is large and a unit block moves out of an area where a detecting process is carried out. SOLUTION: This circuit is provided with a correlative value calculation part 14, a correlative value monitor part 20; a correlative value switching part 22, and a motion vector generation part 16, and outputs switching signal from the correlative value motion part 20 to the correlative value switching part 22 when a correlative value calculated by the correlative value calculation part 13 is larger than a 1st set value (e.g. luminance level 27) to outputs Sm (maximum correlative value that can be calculated by the correlative value calculation part 14) as a 2nd set value to the motion vector generation part 16, thereby making a monitor vector outputted from the motion vector generation part 16 zero. Consequently, when the movement quantity of the animation picture is large and the unit block moves out of the area where the detecting process is performed, none of wrong motion vectors in conventional examples is detected to prevent wiring motion correction by an animation picture correction part coupled with an output terminal 18, thereby improving the picture quality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motion vector detecting circuit for moving image correction for detecting a motion vector used for moving image correction, and the detected motion vector is a PDP (Plasma Display Panel) or LC
In a display device using a D (liquid crystal display panel) (for example, a display device of an address / display separation type driving method), it is used to reduce a visual display shift generated at the time of displaying a moving image.

[0002]

2. Description of the Related Art Recently, as a thin and lightweight display device, P
DP and LCD are attracting attention. The driving method of this PDP is completely different from the conventional CRT driving method, and is a direct driving method using a digitized input video signal. Therefore, the luminance gradation emitted from the panel surface is
It is determined by the number of bits of the signal to be handled.

[0003] PDPs are AC type and D type having different basic characteristics.
It is divided into two types of C type. In the AC type PDP, sufficient characteristics have been obtained with respect to luminance and life, but as for gradation display, only a maximum of 64 gradation display has been reported at the prototype level, but the address / display separation type driving method (ADS) A sub-field method) has been proposed. The drive sequence and drive waveform of the PDP used in this method are as shown in FIGS. 2A and 2B, for example.

FIG. 2A shows a drive sequence of 8 bits and 256 gradations, in which one frame has eight luminance ratios of 1, 2, 4, 8, 16, 32, 64 and 128. Subfields SF1, SF2, SF3, SF4, SF
5, SF6, SF7, and SF8, and a display of 256 gradations is performed by a combination of luminances of eight screens.

[0005] Each subfield is shown in FIG.
As shown in (1), an address period in which data for one refreshed screen is written and a sustain period for determining the luminance level of the subfield are constituted. In the address period, first, wall charges are initially formed on each pixel at the same time for the entire screen, and then a sustain pulse is applied to the entire screen to perform display. The brightness of the subfield is proportional to the number of sustain pulses and is set to a predetermined brightness. In this way, 256 gradation display is realized.

In order to reduce the visual display deviation that occurs when a moving image is displayed on a display device of the address / display separation type driving system as described above, a moving image correcting motion as shown in FIG. A motion vector is detected using a vector detection circuit, and a moving image correction process is performed using the motion vector.

That is, in the motion vector detecting circuit shown in FIG. 3, a frame memory 10 creates a video signal of a current frame screen and a screen of one frame before (hereinafter referred to as a previous frame screen) based on a video signal input to an input terminal 12. Then, the correlation value calculating unit 14 sets a correlation value (difference value) between all the unit blocks in the motion vector detection area of the previous frame screen based on the detection target unit block (for example, 8 × 8 dots) in the current frame screen. ) Are sequentially obtained, and the motion vector generation unit 16 generates a signal (hereinafter, simply referred to as a motion vector) indicating a moving direction and a moving amount from the unit block position of the previous frame screen where the correlation value is minimum to the detection target unit block position. And outputs the motion vector from the output terminal 18 as the motion vector of the unit block to be detected. Unishi which was.

The calculation of the correlation value by the correlation value calculation section 14 is as follows.
It was done as follows. In order to simplify the description, as shown in FIGS. 4A and 4B, the motion vector detection area KS of the previous frame screen is set to 25 blocks (5 blocks × 5 blocks), and the motion vector detection area KS in this motion vector detection area KS images that were in the position of the unit block ZB ₅₁ is a current frame screen assumed to be moved to the position of the unit block GB _33. Also, the unit block ZB ₁₁ of the previous frame screen
To ZB ₅₅ , the unit blocks GB _{11 to} GB of the current frame screen
It is assumed that each of ₅₅ is formed of 2 × 2 dots.

Then, the detection target in the current frame screen
Is a unit block of GB₃₃, The correlation value calculation unit 14
Is the unit block GB₃₃The previous frame image based on
All unit blocks in the surface motion vector detection area KS
ZB₁₁~ ZB₅₅4 (a) shows the correlation value S with
It is sequentially calculated by the following equation along the direction indicated by the arrow.
S = | A1-A2 | + | B1-B2 | + | C1-C2 |
+ | D1-D2 | In the above equation, A1, B1, C1, and D1 are the figures.
5 (a), the unit block ZB of the previous frame₁₁
~ ZB₅₅Displays the brightness level of the dots that form each of
A2, B2, C2, and D2 are as shown in FIG.
To the unit block GB of the current frame ₃₃Of the dots that form
Indicates the luminance level.

The motion vector generation unit 16 compares the correlation value S calculated by the correlation value calculation unit 14 and moves from the position of the unit block ZB ₅₁ of the previous frame screen where the correlation value S is minimum to the unit block of the current frame screen. A movement vector MV to the GB ₃₃ position is generated, and this is used as a unit block GB to be detected.
Output as ₃₃ motion vectors. Motion vectors for other unit blocks of the current frame screen (e.g. GB ₁₁ and GB ₅₅₎ is also determined in a similar manner. At this time, the motion vector detection area KS of the previous frame screen is a detection target unit block (for example, GB ₁₁
, GB ₅₅ ) and 25 blocks around the unit block (for example, ZB ₁₁ or ZB ₅₅ ) of the previous frame screen at the position corresponding to the previous block.

[0011]

However, if the moving amount of the moving image is large and the unit block moves out of the area where the detection processing is being performed, the unit block having the smallest correlation value in the motion vector detection area. Is detected, and a motion vector different from the actual motion vector is detected.

That is, as shown in FIG. 6, an image having a large moving amount of a moving image and located at the position of the unit block ZB ₇₉ on the previous frame screen is different from the unit block G on the current frame screen.
Assuming that has moved to the position of B _33, the unit block ZB ₇₉ is outside the motion vector detection area KS. For this reason, the motion vector generation unit 16 generates a unit block (for example, ZB) having the smallest correlation value in the motion vector detection area KS.
₁₁ ), there is a problem that an erroneous motion vector MVf different from the actual motion vector MVt is detected. Then, when the motion correction unit (not shown) connected to the subsequent stage of the output terminal 18 performs the erroneous motion correction based on the erroneous motion vector as described above, there is a problem that the image quality is deteriorated. If the motion vector detection area KS of the previous frame screen is taken as the entire screen, an erroneous motion vector MVf as described above is not detected, but the entire screen is compared as a motion vector detection area KS for each unit block. It was practically impossible to detect the correlation value. Therefore, a process of detecting a correlation value using a part of one screen as a motion vector detection region KS is performed.
The above-mentioned problem has occurred.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and it is an object of the present invention to detect an erroneous motion vector when a moving amount of a moving image is large and a unit block moves out of an area where detection processing is performed. It is an object of the present invention to provide a motion vector detecting circuit for moving image correction without any.

[0014]

A motion vector detecting circuit for moving image correction according to the present invention calculates a correlation value for all unit blocks in a motion vector detecting area in a previous frame screen with respect to a unit block to be detected in a current frame screen. A correlation value calculator for calculating, a correlation value monitor for monitoring the correlation value calculated by the correlation value calculator and outputting a switching signal when the correlation value is equal to or greater than a first set value, and a switching signal output from the correlation value monitoring unit The correlation value switching unit that switches and outputs the second set value and the correlation value calculated by the correlation value calculation unit based on the presence or absence of the second set value and the correlation value output through the correlation value switching unit is compared. A motion vector from the unit block position of the previous frame screen where the is minimum to the unit block position of the detection target and output as the motion vector of the unit block of the detection target Characterized by comprising; and a vector generator.

The correlation value calculator calculates correlation values for all unit blocks in the motion vector detection area for the unit block to be detected. The motion vector detection area is formed by, for example, an area occupied by a plurality of blocks (5 × 5 = 25 blocks) around the unit block of the previous frame screen located at a position corresponding to the unit block to be detected. .

The correlation value monitoring section monitors the correlation value calculated by the correlation value calculation section and outputs a switching signal when the correlation value is equal to or larger than the first set value. The first set value is set to determine whether or not a unit block corresponding to the unit block to be detected exists in the motion vector detection area. That is, since the luminance level of the unit block corresponding to the moving image does not greatly differ between the current frame screen and the previous frame screen (because the matching ratio increases), the motion amount is smaller than the predetermined value, and When there is a unit block corresponding to the unit block to be detected, the detected correlation value is smaller than the first set value, the amount of motion is larger than a predetermined value, and the detected unit block is included in the motion vector detection area. When there is no corresponding unit block, the detected correlation value becomes larger than the first set value.

The correlation value switching unit calculates a second set value (for example, the maximum correlation value that can be calculated by the correlation value calculation unit) and calculates the correlation value by the correlation value calculation unit based on the presence or absence of a switching signal output from the correlation value monitoring unit. The motion vector generation unit compares the correlation value output through the correlation value switching unit, and outputs the detection target unit block from the unit block position of the previous frame screen where the correlation value is minimum. A movement vector to a position is generated and output as a motion vector of a unit block to be detected.

For this reason, when the moving amount of the moving image is large and the unit block moves outside the area where the detection processing is being performed, the second set value is always correlated by the switching signal output from the correlation value monitoring unit. Since the position is input to the motion vector generation unit via the value switching unit, the position with the smallest correlation value is not detected, and the motion vector generated and output by the motion vector generation unit is zero (zero). That is, the motion vector generation unit generates and outputs a signal indicating that there is no motion of the moving image.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a motion vector detecting circuit for moving image correction according to the present invention will be described below with reference to the drawings. In FIG. 1, the same parts as those in FIG.
In FIG. 1, reference numeral 10 denotes a frame memory. The frame memory 10 delays a video signal input to the input terminal 12 by one frame, generates video signals of a current frame screen and a previous frame screen, and sends the video signal to the correlation value calculation unit 14. It is configured to output.

The correlation value calculator 14 detects a unit block GB (for example, FIG.
The correlation value with all unit blocks (for example, ZB ₁₁ to ZB _{55 in} FIG. 4A) in the motion vector detection area KS of the previous frame screen with reference to (GB ₃₃ composed of 2 × 2 dots) of FIG. (Difference value) are sequentially obtained and output.

Reference numeral 20 denotes a correlation value monitoring unit. The correlation value monitoring unit 20 monitors the correlation value output from the correlation value calculation unit 14, and this correlation value is set to a first set value (for example, a luminance level 27).
(The luminance level when the maximum luminance level that one dot can take is 255) The switching signal is output in the above case.

Reference numeral 22 denotes a correlation value switching unit. The correlation value switching unit 22 determines Sm (maximum correlation value) as a second set value and the correlation value based on the presence or absence of a switching signal output from the correlation value monitoring unit 20. It is configured to switch and output the correlation value calculated by the correlation value calculation unit 14. The Sm is the maximum correlation value that can be calculated by the correlation value calculation unit 14. For example, as shown in FIG. 5, a unit block is composed of 2 × 2 dots, and the maximum luminance level that one dot can take is 255.
Is set (255 × 4) in the case of (8-bit gradation).

The motion vector generation unit 16 compares the correlation values output via the correlation value switching unit 22 and determines a unit block of the previous frame screen where the correlation value is minimum (for example, ZB _{51 in} FIG. 4A). ) to generate a movement vector to GB ₃₃₎ the position of the unit block to be detected (e.g., FIG. 4 (b) from the position, and outputs as a motion vector of a unit block to be detected (e.g., FIG. 4 (b) GB ₃₃ in) It is configured as follows.

Next, the operation of FIG. 1 will be described with reference to FIGS.
Will be described together. Generally, since the luminance level of the unit block corresponding to the moving image does not greatly differ between the current frame screen and the previous frame screen (because the matching ratio becomes large), the luminance level of the detection target is included in the motion vector detection area KS of the previous frame screen. Unit block (for example, GB _{33 in} FIG. 4B)
(For example, ZB _{51 in} FIG. 4A)
Is present, the detected correlation value is smaller than the first set value, and when it is not present (such as GB ₃₃ and ZB _{79 in} FIG. 6), the detected correlation value is smaller than the first set value. growing.

First, FIG. 4A shows a case where a video signal having a small moving amount of a moving image is input to the input terminal 12.
This will be described with reference to FIG. When the motion amount of the moving image is small, the correlation value output from the correlation value calculation unit 14 is smaller than the first set value (for example, the luminance level 27), and thus the correlation value monitoring unit 20 does not output a switching signal. Therefore, the correlation value switching unit 22 outputs the correlation values sequentially output from the correlation value calculation unit 14 to the motion vector generation unit 16, and the motion vector generation unit 16 compares the sequentially input correlation values, and A movement vector (for example, FIG. 4 (A)) from the position of the unit block (for example, ZB _{51 in} FIG. 4 (a)) in the minimum motion vector detection area to the position of the unit block to be detected (for example, GB _{33 in} FIG. 4 (b)). b) is generated and output to the output terminal 18 as a motion vector.

Next, a case where a video signal having a large moving amount of a moving image is input to the input terminal 12 will be described with reference to FIG. If the motion amount of the moving image is large, the correlation value calculation unit 1
Since the correlation value output from No. 4 is equal to or greater than the first set value (for example, the luminance level 27), a switching signal is output from the correlation value monitoring unit 20. Therefore, the correlation value switching unit 22 sequentially outputs the maximum correlation value Sm to the motion vector generation unit 16, and the motion vector generation unit 16 sequentially compares the maximum correlation value Sm. Is not detected, a motion vector of zero (zero) is generated, and the motion vector output to the output terminal 18 is zero.

That is, when the motion amount of the moving image is large as shown by the movement vector MVt in FIG. 6, an erroneous movement vector MVf is not generated and output as in the conventional example, but a zero movement vector is generated. Generate and output. For this reason, a motion compensator (not shown) coupled to the output terminal 18
Does not perform moving image correction processing on a unit block to be detected (for example, GB _{33 in} FIG. 6), but can avoid moving image correction processing using an incorrect movement vector MVf as in the conventional example, thereby improving image quality. be able to.

In the above-described embodiment, the correlation value calculating section calculates the unit block (eg, ZB ₃₃ ) of the previous frame screen at a position corresponding to the unit block (eg, GB ₃₃ ) to be detected.
A plurality of blocks (for example, 25 blocks) around the center are calculated as the motion vector detection area KS, and the correlation value is calculated. However, the present invention is not limited to this. Any method may be used as long as it calculates a correlation value by using a feasible partial area as a motion vector detection area KS. For example, the motion vector detection area KS is
The corresponding unit block of the previous frame screen (for example, Z
B ₃₃ ) as a center (for example, 16 blocks), or a certain area (for example, 2 blocks) including a corresponding unit block (eg, ZB ₃₃ ) of the previous frame screen at a position other than the center.
5 blocks).

In the above embodiment, the case where the second set value output via the correlation value switching unit when the switching signal is present is the maximum correlation value (Sm) that can be calculated by the correlation value calculation unit has been described. However, the present invention is not limited to this. When the second set value is sequentially input to the motion vector generation unit,
The motion vector generation unit may compare the second set value as the correlation value sequentially input, generate a zero motion vector, and output a motion vector of zero.

In the above-described embodiment, the case where the display device is a display device using a PDP has been described. However, the present invention is not limited to this, and the present invention can also be used for a display device using an LCD. .

[0031]

The motion vector detecting circuit for moving image correction according to the present invention includes a correlation value calculating section, a correlation value monitoring section, a correlation value switching section, and a motion vector generating section, and the correlation value calculated by the correlation value calculating section is determined by the correlation value calculating section. When the value is equal to or more than one set value (for example, the luminance level 27), a switching signal is output from the correlation value monitoring unit to the correlation value switching unit, and the motion vector generation unit can calculate the second set value (for example, the correlation value calculation unit) Since the maximum correlation value Sm) is output and the motion vector output from the motion vector generation unit is set to zero, the motion amount of the moving image is large, and the unit block moves outside the area where the detection processing is being performed. In such a case, an erroneous motion vector unlike the related art is not detected. For this reason, it is possible to eliminate erroneous motion correction in the moving image correction unit combined in the subsequent stage,
Image quality can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a motion vector detecting circuit for moving image correction according to the present invention.

FIG. 2 explains a subfield lighting method.
(A) is an explanatory diagram of a drive sequence in a 256-tone method, and (b) is a drive waveform diagram.

FIG. 3 is a block diagram of a motion vector detecting circuit for moving image correction in a conventional example.

FIGS. 4A and 4B are diagrams illustrating an operation when a moving amount of a moving image is small. FIG. 4A is a diagram illustrating a previous frame screen, and FIG. 4B is a diagram illustrating a current frame screen.

5A and 5B show an example of the configuration of a unit block for explaining the calculation of a correlation value. FIG. 5A shows an example in which the brightness level of each dot constituting the unit block (2 × 2 dots) of the previous frame screen is A1, and FIG. A diagram showing B1, C1, and D1,
(B) shows the brightness level of each dot constituting the unit block (2 × 2 dots) of the current frame screen is A2, B2, C
2, D2.

6 is a diagram conceptually illustrating an operation of detecting an erroneous motion vector by the circuit in FIG. 3 when a moving amount of a moving image is large.

[Explanation of symbols]

10 ... frame memory 12 ... video signal input terminal
14 ... correlation value calculation unit 16 ... motion vector generation unit
18: output terminal of motion vector, 20: correlation value monitoring unit, 22: correlation value switching unit, A1, B1, C1, D1
... Brightness level of each dot constituting a unit block (2 × 2 dots) of the previous frame screen, A2, B2, C2, D
2 ... the luminance level of each dot of the unit block (2 × 2 dots) of the current frame screen, GB ₁₁ ~GB ₅₅ ... unit block of the current frame screen, KS ... motion vector detection area of the previous frame screen, MV, MVt , MVf ... motion vector (motion vector), ZB ₁₁ ~ZB ₇₉ ... unit block of the previous frame screen.

Claims (3)

[Claims] 1. A correlation value calculating section for calculating a correlation value for all unit blocks in a motion vector detection area in a previous frame screen for a unit block to be detected in a current frame screen, and a correlation value calculating section calculating the correlation value. A correlation value monitoring unit that monitors a correlation value and outputs a switching signal when the correlation value is equal to or greater than a first setting value; and a second setting value and the correlation value calculation unit based on the presence or absence of a switching signal output from the correlation value monitoring unit. The correlation value switching unit that switches and outputs the correlation value calculated in step 2 is compared with the correlation value output through the correlation value switching unit, and the detection target is determined from the unit block position of the previous frame screen where the correlation value is minimum. And a motion vector generation unit that generates a motion vector to a unit block position of the target block and outputs the motion vector as a motion vector of the unit block to be detected. Correction for the motion vector detection circuit. 2. A correlation value calculating section, comprising: a plurality of unit blocks around a unit block of a previous frame screen located at a position corresponding to a unit block to be detected in a current frame screen; 2. The motion vector detecting circuit according to claim 1, wherein a correlation value is calculated as a detection area. 3. The motion vector detecting circuit according to claim 1, wherein the second set value is a maximum correlation value that can be calculated by the correlation value calculation unit.