CN101387812A

CN101387812A - Camera autofocus system and method

Info

Publication number: CN101387812A
Application number: CNA2007102016803A
Authority: CN
Inventors: 蔡朝链
Original assignee: Hongfujin Precision Industry Shenzhen Co Ltd; Hon Hai Precision Industry Co Ltd
Current assignee: Hangzhou Hikvision Digital Technology Co Ltd
Priority date: 2007-09-13
Filing date: 2007-09-13
Publication date: 2009-03-18
Anticipated expiration: 2027-09-13
Also published as: CN101387812B

Abstract

A camera auto-focus method, which is used for auto-focus when taking pictures of moving human bodies, the method includes the following steps: detecting the relative position of a human face in a first frame, and taking a diagonal of a rectangular frame in the frame Line, get the coordinates of the two vertices of the diagonal line; calculate the area S1 of the rectangular frame in the first picture according to the coordinates of the two vertices of the diagonal line in the first picture; detect the human face in the second picture Take a diagonal line of the rectangular frame in the picture to obtain the coordinates of the two vertices of the diagonal line; calculate the area of the rectangular frame according to the coordinates of the two vertices of the diagonal line in the second picture S2; determine whether S2 is greater than S1; if S2 is greater than S1, then determine that the subject is moving towards the close-up direction and control the camera to focus and scan towards the close-up direction; when S2 is less than S1, control the camera to focus and scan towards infinity. The invention also provides a camera automatic focusing system.

Description

Camera autofocus system and method

Technical field

The present invention relates to a kind of camera autofocus system and method.

Background technology

When taking pictures, the personage is the main body of picture normally, so all focusings, photometry all should be carried out based on character facial.For general camera, the Focus hold operation of this locking that need expose, domestic consumer grasps not too easily.In the market, people's face focusing technology is very universal, and this technology can allow whether camera is discerned automatically the people in the picture face, and automatically with people's face as the main body of taking.Camera all will adjusted at the situation of people's face aspect focusing and the exposure control.Like this, photographer just can be absorbed in the assurance of composition and right moment for camera, can not disperseed energy by loaded down with trivial details operation again.

But, when opening the people of continuous focus function shooting in mobile photo, people's position does not stop to change, then need to change at any time focusing range, at this moment focusing motor can not be judged people's moving direction track, needs constantly front and back scanning focusing and changes focusing range, up to scanning people's face, waste a lot of times, can not be in time and the instantaneous clear pictures of clearly catching the people in moving.

Summary of the invention

In view of above content, be necessary to provide a kind of camera autofocus system, utilize people's appearance for the size variation of whole image and the direction and the track of the continuous focusing of position judgment, reduce the time of focusing.

In view of above content, be necessary to provide a kind of camera method of focusing automatically, utilize people's appearance for the size variation of whole image and the position judgment direction and the track of focusing continuously, reduce the time of focusing.

A kind of camera autofocus system, automatically focus when being used to take mobile human body photo, this system comprises automatically continuously the focusing program and moves the digital information processing system of this automatically continuous focusing program, this digital information processing system stores first picture and second picture, this first picture and second picture are two people's faces focusing pictures that the person of being taken grasps at when moving continuously, described first picture and second picture are lived people's face with the rectangle circle respectively, should automatically continuous focusing program comprise: detecting module, be used for detecting the relative position of people's face at first picture, get a diagonal line of the rectangle frame in this picture, obtain the coordinate on these cornerwise two summits; Computing module is used for the area S1 according to rectangle frame in coordinate Calculation first picture on two summits of the described first picture diagonal line; Described detecting module also is used for detecting the relative position of people's face at second picture, gets a diagonal line of rectangle frame in this picture, obtains the coordinate on these cornerwise two summits; Described computing module is used for the coordinate according to two summits of diagonal line of described second picture, calculates the area S2 of this rectangle frame; Judge module, whether the area S2 of rectangle frame that is used for judging second picture is greater than the area S1 of the rectangle frame in first picture; And Focusing module, being used for as S2 during greater than S1, the control camera scans towards the focusing of close-shot direction; As S2 during less than S1, the control camera is towards unlimited distance focusing scanning.

A kind of camera method of focusing automatically, automatically focus when being used for taking the human body photo that moves, this method comprises the steps: to detect the relative position of people's face in first picture, gets a diagonal line of the rectangle frame in this picture, obtains the coordinate on these cornerwise two summits; Area S1 according to rectangle frame in coordinate Calculation first picture on cornerwise two summits in described first picture; Detect the relative position of people's face in second picture, get a diagonal line of rectangle frame in this picture, obtain the coordinate on these cornerwise two summits; Area S2 according to this rectangle frame of coordinate Calculation on two summits of diagonal line in described second picture; Whether the area S2 that judges the rectangle frame in second picture is greater than the area S1 of the rectangle frame in first picture; If S2, then judges the person of being taken greater than S1 and moves the control camera towards close-shot direction focusing scanning towards the close-shot direction; As S2 during less than S1, the control camera is towards unlimited distance focusing scanning.

Compared to prior art, the present invention utilizes people's appearance for the size variation of whole image and the direction and the track of the continuous focusing of position judgment, reduces the time of automatic focusing.

Description of drawings

Fig. 1 is the hardware Organization Chart of camera autofocus system of the present invention.

Fig. 2 is focus the automatically synoptic diagram of method preferred embodiment of camera of the present invention.

Fig. 3 is the functional block diagram of automatically continuous focusing program among Fig. 1.

Fig. 4 is focus the automatically process flow diagram of preferred embodiment of method of camera of the present invention.

Embodiment

As shown in Figure 1, be the hardware Organization Chart of camera autofocus system of the present invention.This system comprises: automatically continuous focusing program 10, should automatically continuous focusing program 10 run on a numerical digit signal processing system (Digital Signal Process, be called for short DSP) 12, this dsp system 12 stores the picture of the continuous action of the people in captured the moving.

As shown in Figure 2, be focus the automatically synoptic diagram of method preferred embodiment of camera of the present invention.Shown in first picture 1 (hereinafter to be referred as picture 1) and second picture 2 (hereinafter to be referred as picture 2) be two people's faces focusing pictures, and this people's face focusing picture is the picture of the person's of being taken continuous action, lives people's face with a rectangle circle respectively in each picture.

As shown in Figure 3, be the functional block diagram of automatically continuous focusing program 10 among Fig. 1.Should automatically continuous focusing program comprise: detecting module 20, computing module 22, judge module 24, Focusing module 26.

Detecting module 20 is used for detecting the relative position of people's face at picture 1, and described rectangle circle is lived people's face, gets wherein diagonal line of this rectangle focusing frame, obtains the coordinate on these cornerwise two summits, as a M, and some N, as shown in Figure 2.

Computing module 22 is used on average being divided into several lattices according to big young pathbreaker's picture of the object that will take, in the present embodiment, is that example describes to divide 16 lattices.

Described computing module 22, also be used for calculating the area S1 of picture 1 rectangle frame, and calculate the coordinate of the central point O of this frame, the central point O of this rectangle frame promptly is the central point of people's face, point A is in a lattice ABCD, calculate four summits of this grid: the coordinate of some A, some B, some C and some D, as shown in Figure 2, current focusing zone is the zone at grid ABCD place.

Described detecting module 20 also is used for detecting the relative position of people's face at picture 2, and the rectangle circle is lived the people's face in this picture 2, gets a diagonal line of this rectangle, obtains the coordinate on these cornerwise two summits, as a M`, and some N`, as shown in Figure 2.

Described computing module 22, also be used for calculating the area S2 of this rectangle frame of picture 2, and calculate the coordinate of the central point O` of this rectangle frame, some O` is in a lattice A`B`C`D`, calculate four summits of this grid: the coordinate of some A`, some B`, some C` and some D`, as shown in Figure 2.

Judge module 24 is used for the coordinate of judging point A, some B, some C and some D and the coordinate of some A`, some B`, some C` and some D` and whether distinguishes correspondent equal; If unequal, judge that then captured people has left focusing range, need focusing again.

Focusing module 26 is used for when described judge module 24 judges that the people has left focusing range, and the zone of then will focusing is made as the zone at grid A`B`C`D` place.

Described judge module 24 is used to also judge that whether S2 is greater than S1.

Described Focusing module 26 also is used for as S2 during greater than S1, towards macro (close-shot) direction focusing scanning, as S2 during less than S1, towards unlimited distance focusing scanning.

As shown in Figure 4, be focus the automatically process flow diagram of preferred embodiment of method of camera of the present invention.

At first, step S30, computing module 22 on average is divided into a plurality of grids according to the person's of being taken big young pathbreaker first picture and second picture, detecting module 20 is done human face detection and is found out the relative position of people's face in picture 1, and described rectangle circle is lived people's face, gets wherein diagonal line of this rectangle focusing frame, obtain the coordinate on these cornerwise two summits, as a M, some N, as shown in Figure 2.

Step S32, computing module 22 calculates the area S1 of rectangle frame in the picture 1, and calculate the coordinate of the central point O of this frame, the central point O of this rectangle frame promptly is the central point of people's face, point A is in a lattice ABCD, calculate four summits of this grid: the coordinate of some A, some B, some C and some D, as shown in Figure 2, current focusing zone is grid ABCD.

Step S34, the relative position of detecting module 20 detecting people's faces in picture 2, the rectangle circle is lived the people's face in this picture 2, gets a diagonal line of this rectangle, obtains the coordinate on these cornerwise two summits, as a M`, some N`, as shown in Figure 2.

Step S36, described computing module 22 calculates the area S2 of this rectangle frame in the picture 2, and calculates the coordinate of the central point O` of this rectangle frame, and some O` is in a lattice A`B`C`D`, calculate four summits of this grid: the coordinate of some A`, some B`, some C` and some D`, as shown in Figure 2.

Step S38, whether the coordinate of the coordinate of judge module 24 judging point A, some B, some C and some D and some A`, some B`, some C` and some D` distinguishes correspondent equal; If unequal, judge that then captured people has left focusing range, need focusing again.

Whether the area S2 that step S40, judge module 24 judge the rectangle frame in the described picture 2 respectively is greater than the area S1 of the rectangle frame in the picture 1.

Step S42, greater than S1, then Focusing module 26 is toward macro directions focusing scanning as if S2.

Step S44 among the above-mentioned steps S38, when described judge module 24 judges that the people has left focusing range, then changes the focusing center, and the zone of will focusing moves on to grid A`B`C`D`.

Step S46, among the above-mentioned steps S40, less than S1, then described Focusing module 26 is toward unlimited distances focusing scanning as if S2.

Claims

[Claim 1] A camera auto-focus system, which is used for auto-focusing when taking pictures of moving human bodies. The system includes an automatic continuous focusing program and a digital signal processing system that runs the automatic continuous focusing program. The digital signal processing system stores There are a first picture and a second picture, the first picture and the second picture are two human face focus pictures captured continuously when the photographer moves, and the first picture and the second picture respectively use a rectangular frame to frame the human face, It is characterized in that the automatic continuous focusing program includes:

The detection module is used to detect the relative position of the human face in the first frame, and takes a diagonal line of the rectangular frame in the frame to obtain the coordinates of the two vertices of the diagonal line;

A calculation module, configured to calculate the area S1 of the rectangular frame in the first picture according to the coordinates of the two vertices of the diagonal line in the first picture;

The detection module is also used to detect the relative position of the human face in the second picture, take a diagonal line of the rectangular frame in the picture, and obtain the coordinates of the two vertices of the diagonal line;

The calculation module is used to calculate the area S2 of the rectangular frame according to the coordinates of the two vertices of the diagonal line in the second picture;

A judging module, configured to judge whether the area S2 of the rectangular frame in the second frame is larger than the area S1 of the rectangular frame in the first frame; and

The focus module is used to control the camera to focus and scan towards the close-up direction when S2 is greater than S1; when S2 is less than S1, control the camera to focus and scan towards infinity.

[Claim 2] The camera auto-focus system according to claim 1, wherein the calculation module is further configured to divide the first picture and the second picture into a plurality of squares on average according to the size of the subject, Calculate the coordinates of the center point of the rectangular frame in the first picture and the coordinates of the four vertices of the square where the center point is located, and calculate the coordinates of the center point of the rectangular frame in the second picture and the four vertices of the square where the center point is located The coordinates of the vertices.

[Claim 3] The camera auto-focus system according to claim 2, wherein the judging module is also used to judge the coordinates of the four vertices of the square where the center point of the rectangular frame in the first picture is located and the coordinates of the first Whether the coordinates corresponding to the four vertices of the square where the center point of the rectangular frame is located in the second picture are equal, and if they are equal, the focus range is not changed, and the focus range is still within the square where the center point of the rectangle frame is in the first picture; If they are not equal, move the focus area to the square where the center point of the rectangular frame in the second frame is located.

[Claim 4] A camera auto-focus method for auto-focusing when taking a picture of a moving human body, characterized in that the method comprises the following steps:

Detect the relative position of the human face in the first frame, take a diagonal line of the rectangular frame in the frame, and obtain the coordinates of the two vertices of the diagonal line;

Calculate the area S1 of the rectangular frame in the first picture according to the coordinates of the two vertices of the diagonal line in the first picture;

Detect the relative position of the human face in the second picture, take a diagonal line of the rectangular frame in the picture, and obtain the coordinates of the two vertices of the diagonal line;

calculating the area S2 of the rectangular frame according to the coordinates of the two vertices of the diagonal line in the second picture;

Judging whether the area S2 of the rectangular frame in the second picture is greater than the area S1 of the rectangular frame in the first picture;

If S2 is greater than S1, it is judged that the person being photographed moves toward the close-up direction and controls the camera to focus and scan toward the close-up direction;

When S2 is smaller than S1, control the camera to focus and scan toward infinity.

[Claim 5] The camera auto-focus method according to claim 4, characterized in that, before the step of detecting the relative position of the human face in the first frame, the method further includes: according to the size of the person being photographed, the first The first frame and the second frame are equally divided into a plurality of squares.

[Claim 6] The camera auto-focus method according to claim 5, wherein the step of calculating the area S1 of the rectangular frame in the first frame further includes the step of: calculating the area S1 of the center point of the rectangular frame in the first frame Coordinates and the coordinates of the four vertices of the grid where the center point is located; the step calculates the area S2 of the rectangular frame in the second picture and also includes the step of: calculating the coordinates of the center point of the rectangular frame in the second picture and where the center point is located The coordinates of the four vertices of the square.

[Claim 7] The camera auto-focus method according to claim 6, characterized in that, before the step of judging whether the area S2 of the rectangular frame in the second frame is larger than the area S1 of the rectangular frame in the first frame Including: judging whether the coordinates of the four vertices of the grid where the center point of the rectangular frame is located in the first picture and the coordinates corresponding to the four vertices of the grid where the center point of the rectangular frame is located in the second picture are respectively equal; if equal, Then the focus range is not changed, and the focus range is still in the grid where the center point of the rectangle frame is located in the first picture; if they are not equal, the focus area is moved to the grid where the center point of the rectangle frame is in the second picture.