KR101456493B1 - Apparatus and method for processing wide dynamic range in digital image processing device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to an apparatus and method for correcting backlight in a digital image processor for performing backlight correction for an image to which different parameters are applied and for selecting an image to which a desired backlight correction is applied. In the digital image processor, the optical backlight compensation unit performs light backlight correction on an image photographed by the shutter-release button as an input, and adjusts a predetermined parameter for changing the state of the image until the shutter- And digital signal processing means for re-performing the image re-imaging and the back light correction.

Parameter adjustment, optical backlight compensation

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital image processing apparatus,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a digital image processing apparatus and method, and more particularly, to an apparatus and method for correcting backlight in a digital image processor that performs backlight correction on an image to which different parameters are applied.

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 technology such as HDR or WDR, various parameters are adjusted and used. In this technology, the amount of change of the image is large according to the situation of shooting and the setting of parameters, and satisfaction of saturation and contrast , The application of the coarse segmentation parameter may cause the user's dissatisfaction. 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 shoot several images with almost no difference.

Conventionally, the designer of the digital image processing apparatus has to adjust the parameters manually and then obtain the acquired image accordingly. This was not because the WDR always produced a good image by applying certain parameters collectively to the situation (brightness, saturation, reflectivity, etc.) that we focused on at the time of design. In spite of this, the dynamic range can be widened, but the dynamic range limit of the WDR output result has been limited due to the malfunction in the specific situation.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus and method for correcting an optical backlight in a digital image processor that performs optical backlight correction for an image to which different parameters are applied, .

According to an aspect of the present invention, there is provided an apparatus for correcting an optical backlight in a digital image processor, the apparatus comprising: a shutter release button And a digital signal processing means for adjusting a predetermined parameter for changing the state of the image until the button input is released, and re-performing the image re-imaging and the back light correction.

In the present invention, the digital signal processing means may include a parameter converter for adjusting parameters such as saturation or reflectance for adjusting the exposure or color component associated with the luminance component of the photographed image; An optical backlight compensation performing unit for performing optical backlight compensation of the photographed image or the image whose parameters are adjusted; And controlling the backlight correction to be performed on the photographed image as the input of the shutter-release button, adjusting the parameters until the shutter-release button input is released, and then performing the image re- And a control unit for controlling the control unit to be re-executed.

According to another aspect of the present invention, there is provided an apparatus for correcting an optical backlight in a digital image processor, the apparatus comprising: And a digital signal processing means for adjusting the parameters and redoing the backlight correction of the image.

In the present invention, the digital signal processing means may comprise: a buffer for storing the photographed image; A parameter converter for adjusting a parameter such as saturation or reflectance for adjusting an exposure or a color component associated with the luminance component of the stored image; An optical backlight compensation performing unit for performing optical backlight compensation of the stored image or the image whose parameter is adjusted; And a control unit for setting the number of video output items, storing an image photographed by the shutter release button input in the buffer, controlling the backlight correction to be performed on the stored image, adjusting the parameter by the set image output number, And controlling the backlight correction of the stored image to be performed again.

According to a first aspect of the present invention, there is provided a method of correcting backlight in a digital image processor, the method comprising the steps of: (a) performing backlight compensation on an image photographed by a shutter release button; (b) adjusting a predetermined parameter for changing the state of the image until the shutter-release button input is released; And (c) re-capturing the image to which the adjusted parameter is applied and re-performing the backlight correction.

In the present invention, the parameter adjusted in the step (b) may include saturation or reflectance adjusting the exposure or color component related to the luminance component of the photographed image.

According to a second aspect of the present invention, there is provided a method of correcting backlight in a digital image processor, the method comprising the steps of: (a) setting a number of image outputs; (b) storing one image photographed by an input of a shutter-release button; (c) performing light backlight correction on the stored image; (d) adjusting a predetermined parameter for changing the state of the stored image by the set image output number; And (e) re-performing the backlight correction on the image whose parameters have been adjusted.

In the present invention, the parameter adjusted in the step (b) may include saturation or reflectance adjusting the exposure or color component related to the luminance component of the photographed image.

As described above, according to the present invention, parameter adjustment can be applied to bracketing, and a user can select a desired image from the backlight correction results using different parameters

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 23 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 telephoto-zoom button 21t widens the view angle or narrows the view angle depending on the input, in particular, 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 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, A wide angle-zoom button 21w and a telephoto-zoom button 21t for narrowing the angle of view and a touch sensor or a contact-type switch provided in the horizontal and vertical columns around the display unit 23 for character input or menu selection and execution, And buttons B1 to B14 provided with buttons.

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. [

In the present invention, the digital signal processing section 39 operates in two embodiments. The digital signal processing unit 39 as the first embodiment performs the backlight correction on the image photographed by the shutter release button 11 and changes the state of the image until the shutter release button 11 is released Adjusts a predetermined parameter so as to retake the image and perform the backlight correction again.

The digital signal processing unit 39 as the second embodiment adjusts a predetermined parameter for changing the state of the image by the set number of image outputs with respect to the captured image to redo the optical backlight of the image.

First, the operation of the digital signal processing unit 39 of the first embodiment will be described. The digital signal processing unit 39 for performing the first embodiment includes a parameter converting unit 39-1, a WDR performing unit 39-2, and a controlling unit 39-4.

The parameter converter 39-1 adjusts various parameters for changing the state of the image under the control of the controller 39-4. The parameter converter 39-1 can adjust the degree of exposure associated with the luminance component of the photographed image, adjust the degree of saturation associated with the color component of the photographed image, and adjust the reflectivity of the photographed image . In the present embodiment, the parameter conversion unit 39-1 is not limited to the exposure, the saturation and the reflectivity as described above, and any parameter adjustment that changes the state of the image is possible.

The WDR performing unit 39-2 performs the backlight compensation of the photographed image. 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. In FIG. 4, if the ratio of the brightest portion X2 to the darkest portion X1 is expressed in dB, the dynamic range Db can be represented by 20 log (X2 / X1). 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.

The control unit 39-4 controls the WDR execution unit 39-2 to control the image pickup by the shutter-release button 11 to be photographed and to perform the backlight correction on the photographed image. Then, the control unit 39-4 determines whether the shutter-release button 11 is continuously input, and performs bracketing shooting until the input of the shutter-release button 11 is released. When one image is shot Controls the parameter conversion unit 39-1 to adjust parameters (exposure, saturation, reflectivity, etc.), controls the image to be re-imaged with the adjusted parameters, and controls the WDR And controls the performance unit 39-2.

Thus, by applying the parameter adjustment to the bracketing shooting, it is possible to select a desired image from the backlight correction result applying different parameters.

Next, the operation of the digital signal processing unit 39 of the second embodiment will be described. The digital signal processing unit 39 for performing the second embodiment includes a parameter converting unit 39-1, a WDR performing unit 39-2, a buffer 39-3, and a control unit 39-4.

In the case of the first embodiment, the backlight compensation is performed by applying different parameters with different images each time by the shutter-release button 11 input, while in the case of the second embodiment, one photographed image is stored in the buffer 39-3 ), And then performs backlight compensation by applying different parameters to the stored image every time.

The parameter converter 39-1 adjusts various parameters for changing the state of the image under the control of the controller 39-4. The parameter converter 39-1 can adjust the degree of exposure associated with the luminance component of the photographed image, adjust the degree of saturation associated with the color component of the photographed image, and adjust the reflectivity of the photographed image . In the present embodiment, the parameter conversion unit 39-1 is not limited to the exposure, the saturation and the reflectivity as described above, and any parameter adjustment that changes the state of the image is possible.

The WDR performing unit 39-2 performs the backlight compensation of the photographed image. Fig. 4 is a view for explaining the WDR performance, and the contents thereof are the same as those described above, and thus will be omitted.

The control unit 39-4 receives and sets the number of video output items from the user, that is, the number of images to be subjected to the optical backlight correction by parameter adjustment. Thereafter, the shutter-release button 11 is input, and the control unit 39-4 controls the captured image to be stored in the buffer 39-3. The control unit 39-4 controls the WDR execution unit 39-2 so that the backlight correction is performed on the image stored in the buffer 39-3. Subsequently, the control unit 39-4 decreases the number of the set video output by 1 and controls the parameter conversion unit 39-1 to adjust the parameter of the image stored in the buffer 39-3 so that the backlight correction is performed again And controls the WDR performing unit 39-2. The parameter adjustment and the optical backlight correction of the control unit 39-4 are repeated until the number of the set video output is reached.

5A shows the result of changing the exposure parameters and performing the backlight correction on the image stored in the buffer 39-3 in the state where the number of the video output items is set to 6. FIG. 5B shows a result of applying the bracketing shooting until the shutter-release button 11 is released to change the saturation parameter and perform the backlight compensation.

In the present invention, the backlight compensation is performed by adjusting the parameters at the time of image capturing, but it is possible to perform the backlight compensation by adjusting the parameters by bringing in the image already captured and stored.

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.

The operation of the backlight compensation method in the digital image processor according to the first embodiment of the present invention will be described with reference to FIG. In the case of the first embodiment, the backlight compensation is performed by applying different parameters with different images each time by the shutter-release button 11 input.

First, the digital signal processing unit 39 determines whether the digital image processing is set to the bracketing mode (step 601). When set to bracketing mode, multiple images are taken with one shutter release button (11) input.

When the bracketing mode is set, the digital signal processing unit 39 displays the live view image on the display unit 23 (Step 603).

When the first shutter-release button 11 input signal is received (step 605), the digital signal processing unit 39 performs automatic focus adjustment and automatic exposure adjustment on the live view image 607).

When the input signal of the second shutter-release button 11 is received (step 609), the digital signal processor 39 photographs the live view image whose focus and exposure are adjusted (step 611). In the case of the general bracketing mode, a plurality of images are photographed by a single second shutter-release button 11. In this embodiment, only a single image is captured once the second shutter-release button 11 is input .

When the image is photographed, the digital signal processing unit 39 receives RAW data of the image photographed from the image sensor of the image pickup unit 33 and converts it into RGB or YCbCr data (step 613). This signal conversion is for easy application of the backlight compensation.

The digital signal processing unit 39 performs the backlight correction on the converted RGB or YCbCr data (step 615). Fig. 4 is a view for explaining the WDR performance, and the contents thereof are the same as those described above, and thus will be omitted.

Thereafter, the digital signal processing unit 39 determines whether the shutter-release button 11 is in the input state (step 617).

In the case of the shutter-release button 11 input state, the digital signal processing unit 39 modifies a predetermined parameter value for changing the state of the image to perform the backlight correction (step 619). The digital signal processing unit 39 can adjust the degree of exposure associated with the luminance component Y of the converted YCbCr data and adjust the degree of saturation associated with the color component CbCr of the converted YCbCr data, Can be adjusted. In this embodiment, the parameters are not limited to the exposure, the saturation and the reflectivity as described above, and any parameter adjustment that changes the state of the image is possible.

If the parameter value is modified while the second shutter-release button 11 is being input, the digital signal processing unit 39 repeats steps 611 to 619 for retaking the image and re-performing the backlight correction.

When the input state of the shutter release button 11 is released, the digital signal processing unit 39 displays the result of performing the backlight correction according to the parameter adjustment (step 621), and stores the resultant backlight compensation result image selected by the user (Step 623).

Next, the operation of the backlight compensation method in the digital image processor according to the second embodiment of the present invention will be described with reference to FIG. In the case of the second embodiment, the photographed one image is stored in the buffer 39-3 and the backlight correction is performed by applying different parameters to the stored image each time.

First, the digital signal processing unit 39 determines whether the digital image processing is set to the bracketing mode (Step 701). When set to bracketing mode, multiple images are taken with one shutter release button (11) input.

If the bracketing mode is not set, the digital signal processing unit 39 receives the number setting signal of the video output from the user to apply the present embodiment (step 703). Here, the number of video output items means the number of images for which the backlight correction is performed by parameter adjustment.

When the setting of the number of projected output items is completed, the digital signal processing unit 39 displays the live view image on the display unit 23 (Step 705).

When the first shutter-release button 11 input signal is received in step 707, the digital signal processing unit 39 performs automatic focus adjustment and automatic exposure adjustment on the live view image (step 709) step).

When the input signal of the second shutter-release button 11 is received (step 711), the digital signal processor 39 photographs the live view image whose focus and exposure have been adjusted (step 713).

When the image is photographed, the digital signal processing unit 39 receives the RAW data of the image photographed from the image sensor of the image pickup unit 33 and converts it into RGB or YCbCr data (step 715). This signal conversion is for easy application of the backlight compensation.

The digital signal processing unit 39 stores the converted RGB or YCbCr data in the internal buffer 39-3 (step 717)

Subsequently, the digital signal processing unit 39 performs backlight correction on RGB or YCbCr data stored in the buffer 39-3 (step 719). Fig. 4 is a view for explaining the WDR performance, and the contents thereof are the same as those described above, and thus will be omitted.

When the backlight correction is performed, the digital signal processing unit 39 subtracts 1 from the set number of video output items (step 721), and determines whether the number of the video output items is 0 (step 723).

If the number of video output items is not 0, the digital signal processing unit 39 modifies a predetermined parameter value for changing the state of the image to perform the backlight correction (operation 725). The digital signal processing unit 39 can adjust the degree of exposure related to the luminance component Y of the YCbCr data stored in the buffer 39-3 and adjust the degree of exposure associated with the color component CbCr of the YCbCr data stored in the buffer 39-3 The degree of the associated saturation can be adjusted, and the reflectivity of the YCbCr data stored in the buffer 39-3 can be adjusted. In this embodiment, the parameters are not limited to the exposure, the saturation and the reflectivity as described above, and any parameter adjustment that changes the state of the image is possible.

If the parameter value is modified while the number of video output items is not 0, the digital signal processing unit 39 re-performs the backlight correction of the YCbCr data stored in the buffer 39-3 and subtracts 1 from the set number of video outputs And repeats steps 719 through 725 to determine whether the number of image output items is 0 or not.

When the number of video output items becomes 0, the digital signal processing unit 39 displays the result of performing the backlight correction according to the parameter adjustment (Step 727), and stores the resultant backlight compensation result image selected by the user (Step 729 ).

5A shows the result of changing the exposure parameters and performing the backlight correction on the image stored in the buffer 39-3 in the state where the number of the video output items is set to 6. FIG. 5B shows a result of applying the bracketing shooting until the shutter-release button 11 is released to change the saturation parameter and perform the backlight compensation.

In the present invention, the backlight compensation is performed by adjusting the parameters at the time of image capturing, but it is possible to perform the backlight compensation by adjusting the parameters by bringing in the image already captured and stored.

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 image backlight-corrected image selection device in a 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 result of performing WDR by bracketing photographing and converting exposure parameters and saturation parameters.

FIG. 6 is a flowchart illustrating an operation of an image back-corrected image selection method in the digital image processor according to the first embodiment of the present invention.

FIG. 7 is a flowchart illustrating an operation of an image backlight-corrected image selection method in a digital image processor according to a second embodiment of the present invention.

Claims (8)

A shutter release button is operated to perform backlight compensation on an image photographed by the shutter release button and a predetermined parameter for changing the state of the image until the shutter release button is released, And a digital signal processing means for redetecting the backlight. The digital signal processing apparatus according to claim 1, wherein the digital signal processing means A parameter converter for adjusting parameters such as saturation or reflectance for adjusting an exposure or a color component associated with the luminance component of the photographed image; An optical backlight compensation performing unit for performing optical backlight compensation of the photographed image or the image whose parameters are adjusted; And And controlling the backlight correction to be performed on the photographed image as the input of the shutter-release button, adjusting the parameters until the shutter-release button input is released, And a control unit configured to control the backlight unit to perform the backlight correction. Adjusting a predetermined parameter for changing the state of the image by the number of the set video output with respect to the captured one image to generate a plurality of video output items and correcting the backlight correction of the video for each of the plurality of video output items And a digital signal processing means for storing the video output selected by the user out of the plurality of video output items in which the backlight correction is performed again. The digital signal processing apparatus according to claim 3, wherein the digital signal processing means A buffer for storing the photographed image; A parameter converter for adjusting a parameter such as saturation or reflectance for adjusting an exposure or a color component associated with the luminance component of the stored image; An optical backlight compensation performing unit for performing optical backlight compensation of the stored image or the image whose parameter is adjusted; And Sets the number of video output items, stores an image photographed by the shutter-release button input in the buffer, controls the backlight correction to be performed on the stored image, and adjusts the parameter by the set number of image outputs And controlling the backlight correction of the stored image to be performed again. (a) performing a backlight compensation on an image photographed by the shutter-release button; (b) adjusting a predetermined parameter for changing the state of the image until the shutter-release button input is released; And (c) re-capturing the image to which the adjusted parameter is applied and redoing the backlight correction. 6. The method of claim 5, wherein the parameter adjusted in step (b) And a saturation or reflectance adjusting an exposure or a color component associated with the luminance component of the photographed image. (a) setting a number of video output items; (b) storing one image photographed by an input of a shutter-release button; (c) performing light backlight correction on the stored image; (d) adjusting a predetermined parameter for changing the state of the stored image by the number of the set video output; And (e) re-performing the backlight correction on the image whose parameter is adjusted. 8. The method of claim 7, wherein the parameter adjusted in step (b) And a saturation or reflectance adjusting an exposure or a color component associated with the luminance component of the photographed image.

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