KR101448538B1 - Apparatus and method for processing wide dynamic range using braketing capturing in digital image processing device - Google Patents

Abstract

The present invention relates to a digital image processing apparatus and method, and more particularly, to a digital image processor that performs a backlight correction with a combination of a plurality of exposure-bracketed images to enable a user to select an optimal image. Optical backlight compensation apparatus and method. A digital image processor using bracketing in a digital image processor is a digital image processor that performs bracketing photographing until the end condition is satisfied when a shutter-release button is input after an end condition is received, And a digital signal processing means for performing light backlight correction to display the result.

Exposure bracketing, image combination, WDR, user selection

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an apparatus and method for compensating optical backlight using bracketing in a digital image processor,

The present invention relates to a digital image processing apparatus and method, and more particularly, to a digital image processor that performs a backlight correction with a combination of a plurality of exposure-bracketed images to enable a user to select an optimal image. Optical backlight compensation apparatus and method.

In the digital image processing apparatus, there is a disadvantage that the gradation characteristics exhibited by the conventional silver halide film can not be properly reproduced in the digital image processing apparatus due to the dynamic range of the image sensor itself. To cover these shortcomings, high dynamic range (HDR) or wide dynamic range (WDR) technology is becoming a trend in new digital image processing devices. In the case of a technology such as HDR or WDR (hereinafter referred to as WDR), various input images and parameters are adjusted and used. In this technology, Satisfaction such as saturation and contrast is also different. Due to the introduction of the high-speed frame rate image sensor in such a situation, the continuous shooting of the image is speeded up, so that it is possible to take several images with almost no difference.

When WDR is performed using two or more images, two images with different exposure are taken, and the response curves are adjusted based on the images to give a WDR effect. Conventionally, when a designer of a digital image processing apparatus manually photographs different exposure images necessary for performing WDR using a plurality of images, the degree of exposure is taken at a preset value. However, since the characteristics are different for each scene, it is not always possible to obtain the optimum result when performing the WDR. Therefore, in order to obtain the optimum result every time, there arises a problem that a shot image to be used as an input image is selected. When the WDR is performed with images having a small exposure difference, the dynamic range of the resultant image may not be in a range satisfying the user's satisfaction, and an awkward image may be generated when the WDR is performed with images having too large exposure difference, It is not easy to determine the exposure of the image to be used as the input image.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus and method for compensating optical backlight using bracketing in a digital image processor that allows a user to select an optimal image by performing a backlight compensation with a combination of a plurality of exposed bracketing images .

According to an aspect of the present invention, there is provided an apparatus for correcting an optical backlight using bracketing in a digital image processor, the apparatus comprising: a digital image processor for, when a shutter-release button is input after an end condition is received, And digital signal processing means for performing a backlight correction with a combination of the stored images and displaying the result of the backlight correction.

In the present invention, the digital signal processing unit may include: a termination condition receiving unit that receives the number of bracketing shots, the shutter speed, and the exposure difference as the termination condition; An optical backlight correction performing unit for performing optical backlight correction using an image combination as input data; And a control unit for performing bracketing photographing of the image until the end condition is satisfied and outputting the stored combinations of the images to the optical backlight compensation unit and controlling display of the backlight compensation result.

In the present invention, when the control unit outputs combinations of images stored in the light correction unit, the combinations of images having a small exposure difference may be excluded.

According to an aspect of the present invention, there is provided a method of operating a digital image processor, the method comprising: (a) receiving an end condition; (b) performing a bracketing photographing until the end condition is satisfied when the shutter-release button is input; And (c) performing a backlight compensation with a combination of the stored images and displaying the result.

In the present invention, the number of bracketing shots, the shutter speed, and the exposure difference may be set as end conditions in the step (a).

In the present invention, it is possible to exclude combinations of images having a small exposure difference in performing the backlight correction in the step (c).

As described above, according to the present invention, it is possible to maximize the satisfaction of the user by allowing the user to select an optimal image by performing the backlight compensation by performing a combination of a plurality of exposure bracketed images.

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 the image is recorded on the CCD by appropriately exposing the subject in cooperation with the aperture (not shown).

The shutter-release button 11 generates the first and second image pickup signals by the photographer input. When the first shutter-release button 11 is input as a half-shutter signal, the digital image processor focuses and adjusts the amount of light. At this time, the display unit 25 lights green. When the focus of the first shutter-release button 11 is focused and the amount of light is adjusted, a second shutter-release button 11 as a full shutter signal is input to capture an image.

The power button 13 is input for supplying power to the digital image processor and operating it.

The flash 15 illuminates bright light momentarily when shooting in a dark place. The flash mode includes auto flash, forced flash, no flash, red-eye reduction, and slow synchro flash.

The auxiliary light 17 supplies light to the subject so that the digital image processor automatically catches the focus quickly and accurately at the time of lack of light or at night.

The lens unit 19 receives light from an external light source and processes the 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 widens 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 angle-zoom button 21w is input, the size of the selected exposure area is reduced, and when the telephoto-zoom button 21t is input, the size of the selected exposure area is increased.

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

That is, the touch sensors are provided on the buttons B1 to B14 to move up / down / left / right while touching the buttons B1 to B7 of the horizontal row or the buttons B8 to B14 of the vertical row, It is possible to select any value (e.g., color or brightness) of the items, or activate a submenu icon included in the main menu icon.

In addition, the buttons B1 to B14 are provided with a contact type switch, so that the main menu icon and the sub menu icon can be directly selected 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 an optical backlight compensation apparatus using bracketing in the digital image processor according to the present invention. The display unit 23, the user input unit 31, the image pickup unit 33, the image processing unit 35, A storage unit 37, and a digital signal processing unit 39. [

The user input unit 31 includes a shutter-release button 11 which is opened and closed to expose a CCD or a film to light for a predetermined time, a power button 13 for inputting power, A wide angle-zoom button 21w and a telephoto-zoom button 21t for narrowing the angle of view and a touch sensor or a touch sensor provided in the horizontal and vertical columns around the display unit 23 for character input or menu selection and execution. There are buttons B1 to B14 equipped with switches.

The imaging section 33 includes a shutter, a lens section, a diaphragm, and a charge coupled device (CCD) and an ADC (not shown). 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 diaphragm adjusts the amount (light amount) of the incident light according to the degree of opening and closing. The opening / closing degree of the diaphragm is controlled by the digital signal processing section 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 by a digital image processor is performed by a CCD which converts the light reflected from the 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 processing unit 35 processes the digitally converted RAW data so that it can be displayed. The image processing unit 35 removes a black level due to the dark current generated in the CCD and the CFA filter which are full of temperature change. The image processing unit 35 performs gamma correction to encode information in accordance with the nonlinearity of human vision. The image processing unit 35 performs CFA interpolation for interpolating a Bayer pattern implemented with RGA and RGB lines of gamma-corrected predetermined data into RGB lines. The image processing unit 35 converts the interpolated RGB signals into YUV signals, performs edge compensation for filtering the Y signals by a high-pass filter, and calculates color values of the U and V signals using a standard color coordinate system Corrects the color correction, and removes these noises. The image processing unit 35 compresses and processes the Y, U, and V signals from which the noise has been 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 the operations of the image processing unit 35 operate under the control of the digital signal processing unit 39. [

When the shutter-release button 11 is input after the end condition is received, the digital signal processing unit 39 performs bracketing shooting until the end condition is satisfied, performs the back light correction with the combination of the stored images, So that the user can select it.

To this end, the digital signal processing unit 39 includes a termination condition receiving unit 39-1, an exposure measuring unit 39-2, a WDR performing unit 39-3, and a control unit 39-4.

The end condition receiving unit 39-1 receives the bracketing shooting end condition via the user input unit 31. [ The end condition receiving unit 39-1 receives the number of bracketing shots, the shutter speed, and the exposure difference from the user. For example, if the measured exposure value is 1 / 60s, the number of shots is 8, and the exposure difference is 1 Stop, the shutter speed is set to 1 / 4s, 1 / 8s, 1 / 15s, 1 / 1 / 60s, 1 / 125s and 1 / 500s, and a total of 8 images are shot with one shutter-release button (11) input.

The exposure measuring unit 39-2 measures the exposure (EV) of the displayed live view image.

The WDR performing unit 39-3 performs the backlight correction using the image photographed by the exposure bracketing as input data.

Fig. 4 is a diagram for explaining WDR performance. The dynamic range can be seen as the ratio of the brightest and darkest areas within the identifiable range. The dynamic range (Db) = 20 log (X2 / X1) can be expressed as dB if the ratio of the brightest portion X2 to the darkest portion X1 in the identifiable range in FIG. 4A is expressed in dB. However, if two or more faces in the face recognition have a dynamic range (exposure difference of X1 and X2 or more) that the image processor allows, either one of them is inevitable. In order to solve this problem, a method of giving a gain value to a single image differently depending on the luminance of a pixel, a method of correcting a gamma curve, or a method of processing two images of the same scene, The dynamic range is used. Hereinafter, the description of the dynamic range will be omitted since it is already known.

When the shutter release button 11 is input, the control unit 39-4 performs bracketing shooting of the image until the end condition is satisfied, and stores the stored image combination to the WDR performing unit 39-3.

FIG. 5 is a view showing an embodiment of a bracketing photographed image for performing WDR. When the measured exposure value is 1 / 60s, the number of shots is 8, and the exposure difference is 1 Stop, the shutter speed 8 shot images were shot with one shutter-release button (11) input while changing to 1 / 4s, 1 / 8s, 1 / 15s, 1 / 30s, 1 / 60s, 1 / 125s and 1 / 500s .

5, when the number of captured images is eight, the number of combinations of images that can be made different from each other, that is, the number of images input to the WDR performing unit 39-3 is n (n-1) / 2, (1,2), (1,3), (1,4), (1,5), (1,6), (1,7), (1,8), (2,3), , 4), (2,5), (2,6), (2,7), (2,8), (3,4), (3,5), (3,6), ), (3,8), (4,5), (4,6), (4,7), (4,8), (5,6), (5,7) (6, 7), (6, 8), (7, 8).

At this time, since the WDR effect is not so large as in (1, 2), (7, 8), the control unit 39-4 outputs the image combination to the WDR executing unit 39-3 It can be excluded from the image.

When the combination of the images completes the WDR, the controller 39-4 displays the result on the display unit 23 so that the user can shoot a desired image.

Hereinafter, an optical backlight compensation method using bracketing in the digital image processor according to the present invention will be described in detail with reference to FIG. 3, the main algorithm of the operation method according to an exemplary embodiment of the present invention is a method in which a peripheral component in a device And may be performed in the digital signal processing unit 39 with the help of the digital signal processing unit 39.

If the digital image processor is set to the WDR advance mode after bracketing (Step 601), the digital signal processor 39 receives a termination condition setting signal from the user (Step 603). For example, if the measured exposure value is 1 / 60s, the number of shots is 8, and the exposure difference is 1 Stop, the end condition setting is to set the number of bracketing shots, the shutter speed and the exposure difference. Eight images are shot with one shutter release button (11) input while the shutter speed is changed to 1 / 4s, 1 / 8s, 1 / 15s, 1 / 30s, 1 / 60s, 1 / 125s and 1 / do.

After the end condition is set, the digital signal processing unit 39 displays the live view image on the display unit 23 and performs automatic white balance adjustment (AWV) and automatic exposure adjustment (AE) on the live view image (605 step).

When the first shutter-release button 11 is input from the user (step 607), the digital signal processing unit 39 performs automatic white balance adjustment and automatic focus adjustment (AF) on the live view adjusted video image (Step 609).

When the second shutter-release button 11 is input from the user after the automatic focus adjustment is completed (step 611), the digital signal processing unit 39 performs bracketing photographing to store the photographed image, The process proceeds to step 617.

When the second shutter-release button 11 is first input, the digital signal processor 39 photographs and stores the image (step 613).

After the image is photographed, the digital signal processing unit 39 determines whether it is a termination condition (step 615). Shutter conditions, such as the number of bracketing shots, the shutter speed, and the exposure difference, are set as described above, and the digital signal processor 39 determines whether the digital signal processor 39 is a termination condition.

If the end condition is not satisfied, the shutter speed is changed (step 617), and the image is captured again and stored.

For example, if the measured exposure value is 1 / 60s, the number of shots is 8, and the exposure difference is 1 stop, the shutter speed is set to 1 / 4s, 1 / 8s, 1 / 15s, 1 / 1 / 60s, 1 / 125s, and 1 / 500s, and stores a total of 8 images.

Thus, the bracketing photographing steps 613 to 617 are continued until the end condition is satisfied.

Thereafter, if the termination condition is satisfied, the digital signal processing unit 39 performs the WDR using the combination of stored images (step 619). 5, when the number of captured images is eight, the number of combinations of images that can be made different from each other, that is, the number of images input for WDR performance is n (n-1) / 2, , (1,3), (1,4), (1,5), (1,6), (1,7), (1,8), (2,3), 2,5, 2,6, 2,7, 2,8, 3,4, 3,5, 3,6, 3,7, 3, 8), (4,5), (4,6), (4,7), (4,8), (5,6), (5,7), (5,8) , (6,8), (7,8) can be made. In this case, since the WDR effect is not so large as in the case of (1, 2), (7, 8), the digital signal processing unit 39 can exclude the image combination from the input image for performing the WDR have.

When the WDR operation is completed using the proposed image combinations, the digital signal processor 39 displays a result of WDR operation so that the user can select the WDR operation result (Step 621).

The bracketing photographing end condition described in the present invention may be photographed by a preset number of photographs and terminated. When the second shutter-release button 11 is opened, the bracketing photographing may be terminated.

In addition, the images other than the user-selected images may be automatically deleted as a result of the WDR.

Since the load may be large when WDR is performed, WDR can be performed with the reduced image to be displayed to the user, and then WDR can be performed in the original size of the corresponding combination image only for the selected image.

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 illustrating the configuration of an optical backlight compensation apparatus using bracketing in the digital image processor according to the present invention.

FIG. 4 is a diagram for explaining WDR performance in FIG.

5 is a view showing an embodiment of a bracketing photographed image for WDR performance.

6 is a flowchart illustrating an operation of an optical backlight correction method using bracketing in a digital image processor according to the present invention.

Claims (6)

As a digital image processor, When a shutter-release button is input after an end condition for bracketing is received, bracketing is performed until the end condition is satisfied, and the back light correction is performed for each of a plurality of combinations of the stored images And digital signal processing means for displaying a result of the correction for the plurality of combinations. The digital signal processing apparatus according to claim 1, wherein the digital signal processing means An end condition receiving unit for receiving the number of bracketing images, the shutter speed and the exposure difference based on the end condition; An optical backlight correction performing unit for performing optical backlight correction using an image combination as input data; And And a controller for performing bracketing photographing of the image until the end condition is satisfied and outputting the combination of the stored images to the optical backlight correction unit and controlling display of the backlight correction result, Optical backlight compensation system using bracketing. 3. The apparatus according to claim 2, wherein, when the control unit outputs combinations of images stored in the light correction unit, the combinations of images in which the exposure difference between images used in combination is smaller than a predetermined reference are excluded Optical backlight compensation system using bracketing. A method of operating a digital image processor, (a) receiving an end condition for bracketing photographing; (b) performing a bracketing photographing until the end condition is satisfied when the shutter-release button is input; And (c) performing light backlight correction for each of a plurality of combinations of the stored images, and displaying a result of the correction for the plurality of combinations. 5. The method of claim 4, wherein in step (a) Wherein the number of bracketing shots, the shutter speed, and the exposure difference are set as the termination condition. 5. The method of claim 4, wherein in step (c) Wherein the combination of images in which the exposure difference between the images used in the combination is smaller than a preset reference is excluded when performing the light backlight correction.

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