JP3811137B2 - Subject motion detection circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image control technique for controlling a resolution and a frame rate according to stillness / movement of an image in an image captured by a two-dimensional CCD (Charge Coupled Device) sensor constituting a document camera and a liquid crystal panel for drawing the image. Is.
[0002]
[Prior art]
Conventional projectors with document cameras are known.
In this document camera, a subject placed on a subject placement table is imaged by the document camera and enlarged and projected. If this enlarged projection image is to be displayed at the resolution of the projector, it will be displayed at a low frame rate. Therefore, when magnifying and projecting a subject using this projector with a document camera, the subject is moved on the subject stand to place the subject in an optimal position. There was a problem that it did not move.
[0003]
In order to solve this drawback, the following means has been conventionally employed.
This conventional technique will be described with reference to FIG.
In FIG. 5, a document camera part of an optical system such as a CCD camera or a lens for imaging is accommodated in the projector housing, and the projection method is illustrated as front projection. In addition, only basic optical paths are shown for optical systems belonging to known techniques.
[0004]
As shown in FIG. 5, the conventional projector with a document camera includes a CCD imaging unit 1, a CCD signal processing unit 2, a liquid crystal projection unit 3, and a motion detection image control unit 4.
[0005]
The CCD imaging unit 1 includes 11 two-dimensional CCD sensors, 12 imaging lenses, a glass plate on which 14 subjects are placed, two white illumination lamps that illuminate the imaging surface of 15 subjects through the glass plate 14, and light from 16 subjects. The total reflection mirror that reflects the entire visible light and enters the imaging lens 12, the buffer amplifier that sends the output of the two-dimensional CCD sensor 11 to the CCD signal processing unit 2, and the CCD that drives the two-dimensional CCD sensor 11 A drive circuit is used. Reference numeral 13 denotes a planar subject.
[0006]
The subject 13 placed in contact with the glass plate 14 forms an image on the light receiving surface of the two-dimensional CCD sensor 11 through the total reflection mirror 16 and the imaging lens 12 and is photoelectrically converted.
The output of the two-dimensional CCD sensor 11 is sequentially read out by the timing signal of the CCD driving circuit 18 and guided to the CCD signal processing unit 2 as an analog image signal by the buffer amplifier 17.
[0007]
The CCD signal processing unit 2 includes 21 image signal switching circuits, 22 A / D conversion circuits, 23 image processing circuits, and 24 external image signal input connectors.
The image signal switching circuit 21 selects either the internal image signal from the CCD imaging unit 1 or the external image signal from the external image signal input connector 24. The A / D conversion circuit 22 converts the analog image signal output from the image signal switching circuit 21 into a digital signal and inputs the digital signal to the image processing circuit 23.
The image processing circuit 23 digitally processes the setting of the reference black level, γ correction, shading correction, edge enhancement and other image quality improvements, and transfers them to the liquid crystal projection unit 3.
[0008]
The liquid crystal projection unit 3 includes 31 frame memories, 32 image calculation circuits, 33 video output circuits, 34 liquid crystal panels, 35 light source lamps, 36 cold mirrors, 37 total reflection mirrors, and 38 projection lenses. Become.
[0009]
The frame memory 31 stores the digital image signal output from the image processing circuit 23.
The image arithmetic circuit 32 converts the image signal into a resolution that takes into account the resolution of the image signal stored in the frame memory 31 and the resolution of the liquid crystal panel 34. For example, resolution conversion is performed by compressing image data that converts 1280 × 1024 pixels on an SXGA (Super eXtended Graphics Array) screen to 1024 × 768 pixels on an XGA (eXtended Graphics Array) screen.
[0010]
The image signal subjected to the resolution conversion is sent to the video output circuit 33 at a predetermined frame rate.
The video output circuit 33 D / A converts the output of the image arithmetic circuit 32 and generates a video signal necessary for drawing on the liquid crystal panel 34.
The white light from the light source lamp 35 removes unnecessary infrared light by the cold mirror 36, passes through the liquid crystal panel 34 on which the subject is drawn, refracts the optical path by the total reflection mirror 37, and is guided to the projection lens 38.
The subject captured by the two-dimensional CCD sensor 11 is stored in the frame memory 31 as an image signal, drawn on the liquid crystal panel 34, and projected onto a screen (not shown).
[0011]
The motion detection image control function that is a feature of the conventional technique is achieved by adding the motion detection image control unit 4 to the above-described configuration.
The movement of the image can be electrically recognized by monitoring the contents of the frame memory 31 and detecting the change. A motion detection control circuit 41 built in the motion detection image control unit 4 reads an image stored in the frame memory 31 every time a frame is updated, and detects a change in pixel data for the preceding and succeeding frames.
[0012]
The motion detection control circuit 41 determines that a still image has no motion when there is no change in the pixel data, obtains resolution information of the projected image from the image arithmetic circuit 32, and reads out the entire pixel from the CCD drive circuit. 18 is instructed.
The CCD drive circuit 18 generates a timing pulse for reading out all pixels and sends it to the two-dimensional CCD sensor 11.
In response to this, the two-dimensional CCD sensor 11 sends out sensor output signals of all pixels to the CCD signal processing unit 2.
[0013]
The CCD signal processing unit 2 A / D converts the sensor output signal in the same manner as described above. Thereafter, the image is corrected and stored in the frame memory 31 of the liquid crystal projection unit 3.
The liquid crystal projection unit 3 reads image data from the frame memory 31, generates a video signal, draws it on the liquid crystal panel 34, and projects an image on a screen (not shown) through an optical path.
When the motion detection control circuit 41 detects the change in the pixel data, the motion detection control circuit 41 determines that the image is moving, and refers to the resolution information from the image calculation circuit 32 to instruct the CCD drive circuit 18 to read out the pixels. The CCD drive circuit 18 receives this and generates a timing pulse and sends it to the two-dimensional CCD sensor 11.
By thinning out the pixels in this way, the image quality becomes coarse, but the screen drawing becomes faster, and projection that follows a moving subject is possible.
[0014]
[Patent Document 1]
JP 2001-109422 A
[Problems to be solved by the invention]
As described above, a projector with a conventional document camera adds a motion detection image detection unit. Here, a change in pixel data is monitored in units of frames. Thinning-out reading is performed. By doing this, pixels with motion are thinned and read out to follow the movement of the subject, and images without motion are read without thinning out the pixels, so that a fine image is obtained that does not follow the movement of the subject. .
[0016]
However, since this conventional method monitors changes in pixel data in units of frames, even if there is a change in even one pixel, it is determined that the subject is moving, and the pixels are thinned out and read out. However, there is a problem that a rough image is displayed even though it is actually still.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a subject motion detection circuit capable of accurately capturing the actual motion of the subject and detecting the stillness / motion of the subject. To do.
[0017]
[Means for Solving the Problems]
The subject motion detection circuit according to the present invention comprises:
In detecting the stillness / movement of the subject when the subject is captured by the document camera,
Time interval for capturing an image from the document camera, a stationary determination value and a number of times of stationary detection, which are parameters for detecting that the subject is in a partially stationary state, and a parameter for detecting that the subject is in a completely stationary state An operation unit for setting each parameter including a stationary detection time and a motion detection time which is a parameter for detecting a state in which the subject is moving;
The image captured by the document camera is divided into M (M is an integer of 2 or more) blocks determined in advance, and R for each block in units of image capture time intervals from the document camera set in the operation unit. An image processing unit that calculates and stores an average value of each of the components G, B,
Of these M blocks, the average value of each component of R, G, B for each N (N <M and N is an integer) blocks at a predetermined position and the stillness determination value set by the operation unit A control unit for detecting stillness / movement of a subject according to the following procedure based on the number of times of stillness detection, stillness detection time, and motion detection time;
It is characterized by having.
1) The total value of each component of R, G, and B is calculated for each block of N blocks of the i-th image.
2) Calculate the total value of each component of R, G, and B for each block of N blocks of the (i-1) -th image.
3) Calculate the total value of each component of R, G, and B for each block of the N blocks of the (i-2) -th image.
4) Calculate an average value for each corresponding block from the total values calculated in 1) to 3).
5) A variance value is calculated for each block from the total value and the average value obtained in 1) to 4).
6) For each block, the variance value and the stillness determination value are compared, and when the state where the variance value is smaller than the stillness determination value continues for the stillness detection time or longer, it is determined as partial stillness, otherwise it is determined as partial motion. .
7) When all N blocks are determined to be partially stationary, a stationary state is determined. When this state continues for a stationary detection time or longer, it is determined that the subject is stationary.
8) It is determined that the subject is moving when the state determined as the partial movement continues for the movement detection time or longer.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. Here, a description will be given using a document as an example of the subject.
FIG. 1 is a block diagram of a subject motion detection circuit showing an embodiment of the present invention.
Reference numeral 1 denotes a time interval for capturing an image from the document camera 2, a stillness determination value and a number of times of stationary detection, which are parameters for detecting that the document is in a partially stationary state, and a parameter for detecting that the document is in a completely stationary state. An operation unit for setting each parameter including a still detection time and a motion detection time which is a parameter for detecting a moving state of the document, 2 is a document camera for imaging the document, and 3 is an A / D image from the document camera 2 An A / D conversion unit for conversion.
[0020]
4 divides the image from the A / D conversion unit 3 into 64 (= 8 × 8) blocks, and R, G for each block in units of image capture time intervals from the document camera 2 set in the operation unit 1. An image processing unit that calculates and stores an average value of each component of B, 5 for each of the four blocks at positions determined in advance from the average value of each component of R, G, and B for each of the 64 blocks Control for detecting the stillness / movement of the document according to the procedure described later based on the average value of each of the R, G, B components and the stillness determination value set by the operation unit 1, the number of times of stillness detection, the stillness detection time, and the motion detection time. Part.
[0021]
The flow of image data captured by the document camera 2 is as follows.
A document is imaged by the document camera 2, converted to a digital image by the A / D conversion unit 3, and input to the image processing unit 4.
The image processing unit 4 divides an input image into 8 × 8 (= 64) blocks in units of one frame, calculates an average value of each component of R, G, and B for each block and stores it. At the same time, under the control of the control unit 5, the average values of the R, G, and B components of four blocks at predetermined positions are sent to the control unit 5.
[0022]
Next, the operation and action of this circuit will be described.
In this embodiment, as shown in FIG. 4, the screen of one frame is divided into 8 × 8 (= 64) blocks, of which (3, 3), (3, 6), (6, 3) For the four blocks corresponding to (6, 6), it is determined from the image data whether the document is moving or stationary.
[0023]
First, as a parameter from the operation unit 1, the still determination value STOP_LEVEL, the number of still detections STOP_COUNT, the still detection time, and the motion detection time are set in the control unit 5. These parameters are used as follows.
When a state where the variance value calculated for each of the four blocks is less than the stillness determination value STOP_LEVEL continues for the number of stillness detection times STOP_COUNT, it is determined that the block is partially stationary. Otherwise, it is determined as partial motion. If all four blocks are partially stationary, it is determined that they are stationary. When this stillness determination continues for a stillness detection time or longer, it is determined that the document is stationary. On the other hand, when the partial movement determination continues for more than the movement detection time, it is determined that the document is moving.
[0024]
2 and 3 are flowcharts of document stationary / motion detection according to the present invention.
The procedure for detecting the stationary / motion of the document will be described below with reference to FIGS.
FIG. 2 is a part for detecting whether or not each block is partially stationary in the flowchart of the stationary / motion detection of the document according to the present invention, which corresponds to a stage before detecting whether or not the document is stationary. FIG. 3 shows a part for finally detecting the stationary / movement of the document for all four blocks.
[0025]
The control unit 5 outputs R of 4 blocks corresponding to (3, 3), (3, 6), (6, 3) and (6, 6) out of 8 × 8 (= 64) blocks from the image processing unit 4. The average value of each component of G and B is continuously acquired in image capture time interval units.
The four blocks described above from the i-th, (i-1) -th, and (i-2) -th images based on the average values of the R, G, and B components obtained periodically in this way Whether or not the document is stationary is detected based on the flowcharts shown in FIGS.
[0026]
Here, whether each block is stationary will be described with reference to the block (3, 3), which is one of the four blocks.
First, the total value SUM (0) of each component of R, G, and B is calculated from the i-th image by the following calculation formula (S101).
SUM (0) = R (0) (3,3) + G (0) (3,3) + B (0) (3,3) where R (0) (3,3) is the i-th image Average value of R component of (3,3) block, G (0) (3,3) is average value of G component of (3,3) block of i-th image, B (0) (3,3) Is the average value of the B components of the (3, 3) block of the i-th image.
[0027]
Next, the total value SUM (-1) of each component of R, G, B is calculated from the (i-1) th image by the same calculation formula as described above (S102).
SUM (-1) = R (-1) (3,3) + G (-1) (3,3) + B (-1) (3,3)
Here, R (-1) (3,3) is the average value of the R components of the (3,3) block of the (i-1) th image, and G (-1) (3,3) is (i- 1) Average value of G component of (3, 3) block of the first image, B (-1) (3, 3) is average of B component of (3, 3) block of (i-1) th image Value.
[0028]
Subsequently, the total value SUM (−2) of each component of R, G, and B is calculated from the previous matrix by the same calculation formula as described above (S103).
SUM (-2) = R (-2) (3,3) + G (-2) (3,3) + B (-2) (3,3)
Here, R (−2) (3,3) is an average value of R components of the (3,3) block of the previous matrix, and G (−2) (3,3) is (3,3) of the previous matrix. ) The average value of the G component of the block, and B (-2) (3, 3) is the average value of the B component of the (3, 3) block of the previous matrix.
[0029]
Next, an average value AVE is calculated from these three total values SUM (0), SUM (-1) and SUM (-2) by the following formula (S104).
AVE = (SUM (0) + SUM (-1) + SUM (-2)) / 3
[0030]
Next, the variance value VAR (3, 3) is calculated for the three images by the following equation (S105).
VAR (3,3) = (A ² + B ² + C ² ) / 3
Here, A, B, and C are as follows.
A = AVE-SUM (0)
B = AVE-SUM (-1)
C = AVE-SUM (-2)
[0031]
It is determined from the dispersion value VAR (3, 3) obtained in this way, the set stillness determination value STOP_LEVEL and the number of stop detection times STOP_COUNT whether or not the camera is partially stationary (S106). The determination is performed as follows.
When the state in which the variance value VAR (3, 3) is equal to or less than the stillness determination value STOP_LEVEL is continued for the number of stillness detections STOP_COUNT or more, it is determined as partial stillness. If it is not determined that the document is partially stationary, it is determined that the document is partially moving.
[0032]
In the above description, one block out of four blocks for detecting stillness has been described. The description of one block selected here ends, and the determination state is advanced to detection of partial stillness of four blocks. In this determination, partial stationary detection as described above is executed for all four blocks.
[0033]
First, it is determined whether or not it is in a stationary stage (S107). Whether or not it is in the stationary stage is determined by determining whether or not all four blocks that are still detection targets are partially stationary. When all four blocks are partially stationary, it is determined that the stationary stage is in the stationary stage. In other cases, it is determined that the document is partially moved.
[0034]
Next, it is determined whether or not the stationary state continues for a certain time (S108). This determination is made based on whether or not the stationary state continues for a stationary detection time or longer. If the stationary state continues for a certain time or longer, it is determined that the document is stationary (S110). Otherwise, it is determined that the document is a partial movement.
[0035]
When it is determined that the document is partially moved, it is determined whether or not the moving state has continued for a certain time (S109). This determination is made based on whether or not the motion state continues for more than the motion detection time. If the moving state continues for a certain time or longer, it is determined that the document is moving (S111).
[0036]
Based on this determination, when it is determined that the document is in a stationary state, a high resolution image at a low frame rate is displayed. When it is determined that the document is in a moving state, the image is reduced at a high frame rate. A resolution image is output from the document camera 2.
[0037]
【The invention's effect】
According to the present invention, as described above, one screen imaged by the document camera is divided into M blocks, of which N blocks are to be detected and divided into three screens at predetermined time intervals. An average value of each component of R, G, and B is calculated for each block, and a variance value is calculated based on the average value. When the state in which the variance value is equal to or less than a predetermined stillness determination value continues for more than the number of times of stillness detection continues for more than the stillness detection time in all N blocks, the subject is determined to be still, It is determined that the subject is moving when one variance value is equal to or greater than the stillness determination value, or even when all of the variance values are equal to or less than the stillness determination value and the state is less than or equal to the number of stillness detections for more than the motion detection time. Therefore, it is possible to reliably detect stillness / movement of the subject. Using this detection result, we decided to output a high resolution image at a low frame rate from a document camera when in a stationary state, and a high resolution image at a high frame rate when in a moving state. Therefore, since an image following the movement of the subject can be obtained when the subject is aligned, it is easy to perform the alignment, and a document camera that can obtain a fine image after the alignment is completed can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram of a subject motion detection circuit according to an embodiment of the present invention.
FIG. 2 is the first half of a flowchart of subject motion detection.
FIG. 3 is the latter half of the flowchart of subject motion detection.
FIG. 4 is a diagram showing a state where one screen imaged by a document camera is divided into 64 parts.
FIG. 5 is a diagram illustrating a conventional motion detection technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Operation part 2 Document camera 3 A / D conversion part 4 Image processing part 5 Control part

Claims (1)

In detecting the stillness / movement of the subject when the subject is captured by the document camera,
Time interval for capturing an image from the document camera, a stationary determination value and a number of times of stationary detection, which are parameters for detecting that the subject is in a partially stationary state, and a parameter for detecting that the subject is in a completely stationary state. An operation unit for setting each parameter including a stationary detection time and a motion detection time which is a parameter for detecting a state in which the subject is moving;
An image captured by the document camera is divided into M (M is an integer of 2 or more) blocks determined in advance, and R for each block in units of image capture time intervals from the document camera set in the operation unit. An image processing unit that calculates and stores an average value of each of the components G, B,
Among the M blocks, the average value of each component of R, G, and B for each N (N <M and N is an integer) blocks at a predetermined position and the stillness determination value set by the operation unit A control unit for detecting stillness / movement of a subject according to the following procedure based on the number of times of stillness detection, stillness detection time, and motion detection time;
A motion detection circuit for a subject.
1) The total value of each component of R, G, and B is calculated for each block of N blocks of the i-th image.
2) Calculate the total value of each component of R, G, and B for each block of N blocks of the (i-1) -th image.
3) Calculate the total value of each component of R, G, and B for each block of the N blocks of the (i-2) -th image.
4) Calculate an average value for each corresponding block from the total values calculated in 1) to 3).
5) A variance value is calculated for each block from the total value and the average value obtained in 1) to 4).
6) For each block, the variance value is compared with the static discriminant value, and when the variance value is smaller than the static discriminant value for more than the static detection time, it is determined as partial static, otherwise it is determined as partial motion. .
7) When all the N blocks are determined to be partially stationary, the stationary state is set. When this state continues for the stationary detection time or longer, it is determined that the subject is stationary. Otherwise, the partial movement is determined.
8) It is determined that the subject is moving when the state determined as the partial movement continues for the movement detection time or longer.

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