KR101373018B1 - Apparatus and method for preventing hand-shaking during low light amount in digital image processing device - Google Patents

Abstract

The present invention relates to a digital image processor and a method of operating the same. More particularly, when the image is taken in a low light state, the camera searches for a bright light source from the image, focuses on the exposure, and secures a fast shutter speed by securing a fast shutter speed. The present invention relates to an apparatus and a method for preventing camera shake at low light levels in a digital image processor. In the digital image processor, the image stabilization device at low light level gradually increases the AF window size to search for a bright light source from the image when AF fail occurs due to lack of light in the live view image, and adjusts the focus and exposure based on this. And digital signal processing means for performing a fast shutter speed.

AF Fail. Magnify AF window, user-set shutter speed, focus and exposure adjustment

Description

Apparatus and method for preventing hand-shaking during low light amount in digital image processing device}

The present invention relates to a digital image processor and a method of operating the same. More particularly, when the image is taken in a low light state, the camera searches for a bright light source from the image, focuses on the exposure, and secures a fast shutter speed by securing a fast shutter speed. The present invention relates to an apparatus and a method for preventing camera shake at low light levels in a digital image processor.

Image stabilization in a digital image processor is an important issue that occupies the core of the performance of a digital image processor. Therefore, various image stabilization techniques, such as an optical image stabilization technology, advanced shake reduction (ASR) or a high sensitivity digital image processor, have been applied to a digital image processor. Among these, the optical image stabilizer technology and the ASR are effective for camera shake, but cannot prevent the shaking of the subject. In addition, the application of a high-sensitivity digital image processor can prevent camera shake and subject movement, but the image quality is deteriorated due to noise amplification.

Patent Application No. 1997-113948 discloses a method of photographing by delaying the shutter operation time for a predetermined time when the shutter speed of a subject to be photographed at half shutter speed is slower than the set speed. This is a method for preventing camera shake that may occur when the user presses the shutter. However, when photographing in a dark place where the amount of light is low, the shutter speed is very slow and not effective.

The shutter speed is closely related to the amount of light. To suit the exposure of the digital image processor, the shutter speed and aperture are adjusted appropriately. In other words, when the amount of light is small, the aperture is increased and the shutter speed is slow, whereas when the amount of light is large, the aperture is small and the shutter speed is increased.

When the image is taken after sunset, the surroundings are dark, so that the shutter speed becomes slow and it becomes very vulnerable to the shaking of the user or the subject, so it is difficult to capture the shake-free image. In this case, when shooting with a flash, the image can be taken without shaking, but if the image is taken using the flash at night, the value of the image may be reduced.

The technical problem to be solved by the present invention is in a digital image processor that minimizes camera shake by securing a fast shutter speed by magnifying the AF window to find a bright light source from the image to adjust the focus and exposure when the image is taken in a low light state The present invention provides a device and method for preventing camera shake at low light amount.

In the digital image processor to solve the technical problem to be solved by the present invention, the image stabilization device during low light amount when the AF Fail occurs due to lack of light for the live view image by gradually increasing the size of the AF window to bright light source from the image And digital signal processing means for securing a fast shutter speed by performing focus and exposure adjustment based on this.

The digital signal processing means may include: an AF adjusting unit for generating an AF window in the live view image by inputting a first shutter-release button and adjusting a focus in the AF window; An AE adjustment unit configured to adjust the exposure of the image by receiving the focus adjustment success of the AF adjustment unit; A window size adjusting unit for adjusting the size of the AF window according to a control signal; And outputting the control signal for adjusting the size of the AF window when receiving an AF fail due to lack of light from the AF adjusting unit, and performing focus and exposure adjustment of the image when a bright light source is found on the enlarged AF window. It may include a control unit to ensure a fast shutter speed by controlling the AF adjustment unit and the AE adjustment unit to.

In the present invention, the control unit receives the minimum shutter speed setting signal from the user, and the control to adjust the size of the AF window when the shutter speed at the time of inputting the first shutter release button is lower than the set shutter speed When a bright light source is found on the enlarged AF window again, the AF control unit and the AE control unit may be controlled to perform the focus and exposure adjustment of the image to secure a fast shutter speed.

In order to solve the technical problem to be achieved by the present invention, a method for preventing image stabilization during low light amount in a digital image processor may include (a) an AF window when AF fail occurs due to insufficient light after inputting a first shutter-release button for a live view image. Gradually increasing the size; And (b) if a bright light source is found from the image during the enlargement of the AF window size, performing a focus and exposure adjustment based on the image to secure a fast shutter speed.

In the present invention, the minimum shutter speed setting signal may be received from the user before step (a).

In the present invention, when the shutter speed at the time of inputting the first shutter release button is slower than the set shutter speed, when the AF window size is gradually enlarged and a bright light source is searched from the image during the AF window size enlargement, Based on this, focus and exposure adjustment can be performed to secure a fast shutter speed.

As described above, according to the present invention, when an AF fail occurs when capturing an image in a low light state, the AF window can be enlarged to find a bright light source from the image and adjust focus and exposure to secure a fast shutter speed to minimize camera shake. Can be.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view showing the front and top contours of a digital image processor.

The shutter release button 11 is opened and closed to expose the CCD or film to light for a predetermined time, and records the image on the CCD by properly exposing the subject in conjunction with an aperture (not shown).

The shutter release button 11 generates the first and second image capturing signals by a photographer input. When the first shutter release button 11 as a half shutter signal is input, the digital image processing apparatus focuses and adjusts the amount of light, and when the focus is achieved, the green light is turned on in the display unit 25. . When focus is achieved by the input of the first shutter release button 11 and the amount of light is adjusted, the second shutter release button 11 as a full shutter signal is input to capture an image.

The power button 13 is input to supply power to and operate the digital image processing apparatus.

The flash 15 brightens the bright light instantly when shooting in a dark place. The flash mode includes auto flash, forced flash, flash off, red-eye reduction, and slow synchro.

The auxiliary light 17 supplies light to the subject so that the digital image processing apparatus automatically focuses quickly and accurately when the amount of light is insufficient or at night.

The lens unit 19 receives light from an external light source and processes an image.

FIG. 2 is a rear view showing the rear external appearance of the digital image processor shown in FIG. 1. The wide-angle zoom button 21w, the telephoto-zoom button 21t, the display unit 23, Input buttons B1 to B14 (hereinafter referred to as buttons B1 to B14).

The wide-angle zoom button 21w or the tele-zoom button 21t increases the angle of view or narrows the angle of view depending on the input, particularly when the size of the selected exposure area is to be changed. When the wide-zoom button 21w is input, the size of the selected exposure area is reduced, and when the tele-zoom button 21t is input, the size of the selected exposure area is increased.

The buttons B1 to B14 are provided in the horizontal column and the vertical column of the display unit 23. The buttons B1 to B14 provided in the horizontal and vertical columns of the display unit 23 are provided with a touch sensor (not shown) or a contact switch (not shown).

That is, the buttons B1 to B14 are provided with a touch sensor to move up / down / left / right in a state where the buttons B1 to B7 in the horizontal row or the buttons B8 to B14 in the vertical row are touched. You can select any value (eg, color or brightness) from the items, or activate the submenu icons included in the main menu icon.

In addition, the button frame (B1 ~ B14) is provided with a contact switch, it is possible to directly select the main menu icon and sub-menu icon to execute the corresponding function. The touch sensor requires a relatively weak touch compared to the contact switch input, but the contact switch input requires a relatively strong touch compared to the touch sensor input.

3 is a block diagram showing the configuration of the image stabilizer when low light amount in the digital image processor according to the present invention, the display unit 23, the user input unit 31, the imaging unit 33, the image processing unit 35, And a storage unit 37 and a digital signal processing unit 39.

The user input unit 31 includes a shutter release button 11 that is opened and closed to expose a CCD or a film to light for a predetermined period of time, a power button 13 that inputs power to supply power, Zoom button 21w and telephoto-zoom button 21t for narrowing down the screen and a touch sensor or contact type switch provided in the horizontal and vertical columns around the display unit 23 for character input or menu selection and execution, And button buttons (B1 to B14).

The imaging unit 33 includes a shutter, a lens unit, an aperture, a charge coupled device (CCD), and an ADC, which are not shown in the figure. The shutter is a mechanism that adjusts the amount of light that is exposed with the iris. The lens unit receives light from an external light source and processes the image. At this time, the iris adjusts the amount of light incident (light quantity) according to the degree of opening and closing. The opening and closing degree of the iris is controlled by the digital signal processing unit 39.

The CCD accumulates the amount of light input through the lens unit and outputs the image captured by the lens unit according to the accumulated light amount in accordance with the vertical synchronization signal. Image acquisition of a digital image processing apparatus is performed by a CCD which converts light reflected from a subject into an electrical signal. In order to obtain a color image using a CCD, a color filter is required, and a filter (not shown) called a color filter array (CFA) is employed in most cases. CFA has a regularly arranged structure that passes only light that represents one color per pixel, and it has various forms according to the arrangement structure. The ADC converts the analog video signal output from the CCD into a digital signal.

The image processor 35 performs signal processing to display the digitally converted RAW data. The image processor 35 removes the black level caused by the dark current generated by the CCD and the CFA filter that are sensitive to the temperature change. The image processor 35 performs gamma correction to encode information according to nonlinearity of human vision. The image processor 35 performs CFA interpolation to interpolate the Bayer pattern implemented by the RGRG line and the GBGB line of the gamma corrected predetermined data into the RGB line. The image processing unit 35 converts the interpolated RGB signal into a YUV signal and filters the Y signal by a high band filter to clearly process the image, and uses the standard color coordinate system to adjust the color values of the U and V signals. Perform color correction to correct and remove their noise. The image processor 35 compresses and signals the Y, U, and V signals from which the noise is removed to generate a JPEG file, and the generated JPEG file is displayed on the display unit 23 and stored in the storage unit 37. . All of the operations of the image processor 35 operate under the control of the digital signal processor 39.

The digital signal processing unit 39 gradually increases the size of the AF window and generates a bright light source from the background of the live view image when the AF fail occurs due to lack of light after the first shutter-release button 11 is input to the live view image. Search, and focus and exposure adjustment based on this to ensure a fast shutter speed.

To this end, the digital signal processor 39 includes an AF adjuster 39-1, a window size adjuster 39-2, an AE adjuster 39-3, and a controller 39-4.

The digital signal processor 39 provides a menu for performing an image stabilization function at low light, and provides a sub-menu in which the user sets a minimum shutter speed to store the minimum shutter speed set by the user.

When the user inputs the first shutter release button 11 in a state in which the image stabilizer function is selected in the low light amount, the AF adjusting unit 39-1 displays the first AF window 401 in the live view image as shown in FIG. 4. ) And perform AF adjustment in the first AF window 401.

However, when the amount of light is insufficient, an AF fail occurs in the first AF window 401. When photographing in this state, the shutter speed becomes very slow, for example, about 1/2 second to 1 second, which is very likely to cause shaking. The AF adjusting unit 39-1 notifies the control unit 39-2 when an AF fail occurs in the first AF window 401.

The window size adjusting unit 39-2 receives the window size control signal of the control unit 39-4 to enlarge the AF window size. For example, the second AF window 403 and the third AF window ( 405).

The controller 39-4 searches for a bright light source from the enlarged AF window. For example, no bright light source is searched in the second AF window 403 of FIG. 4. In this case, the controller 39-4 outputs the window resizing signal to the window resizing unit 39-2 again, and the window resizing unit 39-2 displays the window as in the third AF window 405 of FIG. 4. Zoom in. The controller again searches for a bright light source from the third AF window 405 and notifies the AF adjuster 39-1 when the bright light source is found.

The AF adjuster 39-1 receives the bright light source search signal from the controller 39-4, and determines the brightest place with reference to the AF data in the enlarged AF window, that is, the third AF window 405. The AF adjusting unit 39-1 calculates the maximum focus value while moving the focus lens (not shown) in the third AF window 405.

The AE adjustment unit 39-3 performs exposure at the maximum poker value calculated by the AF adjustment unit 39-1.

After the focus adjustment and the exposure adjustment are completed based on the searched bright light source, the controller 39-4 compares the shutter speed at the time of input of the first shutter release button 11 with the minimum shutter speed set by the user. . When the shutter speed at the time of inputting the first shutter release button 11 is slower than the minimum shutter speed set by the user, the controller 39-4 controls the window size adjusting unit 39-2 to enlarge the AF window further. Outputs and controls focus and exposure adjustment for the brightest spot in the magnified AF window. If the shutter speed of the first shutter release button 11 is faster than the minimum shutter speed set by the user, the controller 39-4 controls the shutter speed at the time of input of the first shutter release button 11, the adjusted focus and the like. Shoot images based on exposure.

4 shows the outdoor night view after sunset in a live view state. When shooting images with ISO Auto while the flash is not operating, the shutter speed is about 1/2 second to 1 second, for example, and it is difficult to shoot a steady image without a tripod.

To shoot images with minimal blur without a tripod, the user sets the minimum shutter speed (e.g. 1/6 second). When the first shutter-release button 11 is input in the live view image to capture an image in the first AF window 401 state, AF fail occurs due to the low light amount.

When an AF fail occurs, the window size is enlarged from the first AF window 401 to the second AF window 403, AF is performed on the confirmed second AF window area 403, and the second AF window is opened. The area 403 also causes an AF fail due to the low light amount.

In this case, the window size is enlarged from the second AF window 403 to the third AF window 405, and AF is performed on the confirmed third AF window region 405. In the third AF area 405, a bright light source is found through AF, and focus and exposure adjustment is performed on the bright light source as a target.

If the shutter speed at the time of inputting the first shutter release button 11 is slower than the minimum shutter speed set by the user, the above operation is repeated by enlarging the AF window further. If the shutter speed at the time of inputting the first shutter release button 11 is faster than the minimum shutter speed set by the user, the second shutter release button is input to capture an image.

The AF window enlargement process and the display of the bright light source area may be displayed for the user to view according to the user's setting.

Hereinafter, a method of preventing camera shake at low light amount in the digital image processor according to the present invention will be described in detail. In the digital image processor according to the present invention, the image stabilization method in the low light amount may be performed in the digital image processing apparatus as shown in FIG. 3. According to an embodiment, the main algorithm of the operation method may include peripheral components in the apparatus. It may be performed inside the digital signal processing unit 39 with the help of these.

The digital signal processor 39 provides a menu for performing an image stabilization function in a low light amount, and provides a sub-menu in which the user sets a minimum shutter speed.

When the image stabilizer menu is selected in the low light amount, the digital signal processor 39 receives a minimum shutter speed value set by the user (step 501).

Thereafter, the user composes a photograph while watching the live view image, inputs the first shutter release button 11, and the digital signal processor 39 receives the received image (step 503).

When the input of the first shutter release button 11 is received, the digital signal processor 39 generates an AF window and performs AF based on the AF window (step 505). Referring to FIG. 4, the digital signal processing unit 39 receiving the first shutter release button 11 sets the first AF window 401 in the live view image, and performs AF based on this. do.

Subsequently, the digital signal processor 39 determines whether an AF fail occurs due to lack of light in the corresponding AF window (step 507).

When an AF fail occurs in the AF window, the digital signal processing unit 39 enlarges the AF window (step 509), and repeats steps 505 and 507. Referring to FIG. 4, when an AF fail occurs due to a low light amount in a state of the first AF window 401, the window size is enlarged from the first AF window 401 to the second AF window 403. When AF is performed on the confirmed second AF window area 403 and the second AF window area 403 is also caused by the low light amount, the window size is determined by the second AF window 403. 3, the AF window 405 is enlarged and AF is performed on the expanded third AF window area 405. If a bright light source is searched for through the AF in the third AF area 405, the AF succeeds.

If no AF fail occurs in the AF window area, the digital signal processing unit 39 adjusts the exposure to the target AF value that has been successful above, and checks the shutter speed at the time of input of the first shutter release button 11. (Step 511).

The digital signal processor 39 compares the shutter speed at the time of inputting the first shutter release button 11 with the minimum shutter speed set by the user (step 513).

When the shutter speed at the time of inputting the first shutter release button 11 is slower than the minimum shutter speed set by the user, the digital signal processing unit 39 further enlarges the AF window, and places the lightest in the enlarged AF window. Steps 509, 505, 507, and 511 for performing focus adjustment and exposure adjustment for the image are sequentially performed.

When the shutter speed of the first shutter release button 11 is faster than the minimum shutter speed set by the user, the digital signal processor 39 determines that focus and exposure adjustment are completed (step 515).

Subsequently, upon receiving the input of the second shutter release button 11 (step 517), the digital signal processor 39 based on the shutter speed, the adjusted focus, and the exposure when the input of the first shutter release button 11 is inputted is performed. Shoot the Live View image (step 519).

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view showing the front and top contours of a digital image processor.

FIG. 2 is a rear view showing the rear external shape of the digital image processor shown in FIG. 1; FIG.

3 is a block diagram showing the configuration of an image stabilizer when low light amount in a digital image processor according to the present invention.

4 is a view showing a bright light source by enlarging an AF window when an AF fail occurs due to lack of light in FIG. 3.

5 is a flowchart illustrating the operation of the image stabilization method during low light amount in the digital image processor according to the present invention.

Claims (6)

As a digital image processor, When AF Fail occurs due to lack of light in the Live View image, the AF window size is gradually enlarged to search for a bright light source from the image, and based on this, digital signal processing means for securing a fast shutter speed by performing focus and exposure adjustment. Anti-shake device at low light amount comprising a. The digital signal processing apparatus according to claim 1, wherein the digital signal processing means An AF adjusting unit for generating an AF window in the live view image by inputting a first shutter-release button and adjusting a focus in the AF window; An AE adjustment unit configured to adjust the exposure of the image by receiving the focus adjustment success of the AF adjustment unit; A window size adjusting unit for adjusting the size of the AF window according to a control signal; And When receiving an AF fail due to lack of light from the AF adjusting unit, the control signal for adjusting the size of the AF window is output, and when a bright light source is found on the enlarged AF window, focus and exposure adjustment of the image is performed. And a controller for controlling the AF adjusting unit and the AE adjusting unit to secure a fast shutter speed. 3. The apparatus of claim 2, wherein the control unit Receiving a minimum shutter speed setting signal from a user, and when the shutter speed at the time of inputting the first shutter release button is slower than the set shutter speed, outputs the control signal for adjusting the size of the AF window again, and enlarges the enlargement. And a bright light source is detected on the AF window to control the AF control unit and the AE control unit to perform focus and exposure adjustment of the image, thereby ensuring a fast shutter speed. A method of operating a digital image processor, (a) gradually increasing the AF window size when the AF fail occurs due to insufficient light after inputting the first shutter-release button to the live view image; And and (b) if a bright light source is found from the image during the enlargement of the AF window size, performing a focus and exposure adjustment based on the image to secure a fast shutter speed. The method of claim 4, wherein the minimum shutter speed setting signal is received from the user before step (a). 6. The method of claim 5, If the shutter speed at the time of inputting the first shutter release button is slower than the set shutter speed, the AF window size is gradually enlarged, and if a bright light source is found from the image during the AF window size expansion, the focus is based on this. And performing a exposure adjustment to secure a fast shutter speed.

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