KR20100010836A - Image processing method and apparatus, and digital photographing apparatus using thereof - Google Patents

Abstract

PURPOSE: An image processing method and an apparatus, and a digital photographing apparatus using thereof are provided to improve the quality of photographed image by gamma correction. CONSTITUTION: A face region detecting part(73) detects a face area in the input image. An image signal processor(72) performs the AE(Auto-Exposure) calculation around the face area detected as described above. A gamma correction controller(74) makes the image signal processor compensates the gamma curve based on the AE operation result. The gamma correction controller revises the gamma curve of the AE target part. The image processing mode selection unit selects the image processing mode about the input image.

Description

Image processing method and apparatus, and digital photographing apparatus using Technical Field

The present invention relates to image processing, and more particularly, to an image processing method and apparatus capable of smoothly and softly processing image quality during image capturing using gamma correction.

Techniques for detecting an object, such as a face, from an image obtained by shooting in a digital camera, and processing an image according to the detection result of the object, for example, adjusting the white balance according to the brightness of a subject, Increasingly, technologies for controlling whether or not the flash is emitted according to the brightness of the subject are increasing.

On the other hand, users of digital cameras have a strong desire to have their pictures taken more beautifully and brightly. These users are inconvenient to use the image editing program such as Photoshop to move the picture stored in the digital camera to the PC to edit the picture.

According to the needs of these users, recently released digital cameras are equipped with a so-called "burning mode" function, which makes the portrait taken by the user bright. If you take a picture with such a “bright mode”, you can get a bright and bright picture, especially the face's skin.

However, such a "burn mode" performs a face detection on the captured image, and if there is a face, blurs the entire image, thereby reducing the resolution of the entire image. In particular, since the entire face of the person is blurred, a phenomenon in which the entire face is inferior in sharpness occurs.

The present invention has been made to solve the problems of the prior art, and an object of the present invention is to provide an image processing method and apparatus capable of smoothly and softly processing the image quality of an image photographed using gamma correction.

Another object is to provide a digital photographing apparatus using the same.

In order to achieve the above technical problem, an image processing method according to an embodiment of the present invention comprises the steps of: (a) detecting a predetermined face area from an input image; (b) performing an AE operation around the detected face area; And (c) controlling to correct a gamma curve based on the AE calculation result.

Preferably, the step (c) is characterized in that to control to correct the gamma curve of the AE target portion.

Preferably, step (c) is characterized in that to control the gamma of the AE target portion to a high.

Preferably, in the step (c), the contrast of the input image is controlled to be low.

Preferably, before the step (a), further comprising the step of selecting an image processing mode for the input image.

Preferably, steps (b) to (c) are performed when at least one facial region is detected in the input image in step (a).

According to another aspect of the present invention, there is provided an image processing apparatus including a face region detector configured to detect a predetermined face region from an input image; An image signal processor which performs an AE operation based on the detected face region; And a gamma correction controller configured to control the image signal processor to correct a gamma curve based on the result of the AE operation.

Preferably, the gamma correction control unit controls to correct a gamma curve of the AE target portion.

Preferably, the gamma correction controller is characterized in that to control the gamma of the AE target portion high.

Preferably, the gamma correction controller controls the contrast of the input image to be low.

The image processing apparatus may further include an image processing mode selector configured to select an image processing mode for the input image.

In order to achieve the another technical problem, a recording medium including a program for executing the method on a computer according to another embodiment of the present invention.

In order to achieve the another technical problem, a digital photographing apparatus including the image processing apparatus according to another embodiment of the present invention.

The image processing method according to an exemplary embodiment of the present invention may maximize the effect of the brightness of the overall image by processing the image quality smoothly and softly on the face region and the region having similar luminance instead of the entire image.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, only parts necessary for understanding the operation according to the present invention will be described, and descriptions of other parts may be omitted so as not to distract from the gist of the present invention.

In addition, the terms or words used in the specification and claims described below are not to be construed as being limited to the ordinary or dictionary meaning, meaning that corresponds to the technical spirit of the present invention so as to best express the present invention To be interpreted as

1 is a block diagram of a digital camera according to an embodiment of the digital photographing apparatus 100 of the present invention. 2, which will be described with reference to FIG. 1, is a block diagram illustrating the digital signal processor 70 of the digital photographing apparatus.

As shown in FIG. 1, the digital camera 100 includes an optical unit 10, an optical driver 11, an imaging device 15, an imaging device controller 16, an operation unit 20, and an image processing mode selector ( 21, the program storage unit 30, the buffer storage unit 40, the data storage unit 50, the display control unit 60, the data driver 61, the scan driver 63, the display unit 65 and the digital signal processing unit (DSP, 70).

The optical unit 10 receives an optical signal from a subject and provides it to the imaging device 13. The optical unit 10 may include at least one lens, such as a zoom lens for controlling the view angle to be narrowed or widened according to a focal length, and a focus lens for focusing a subject. In addition, the optical unit 10 may further include an aperture for adjusting the amount of light.

The optical driver 11 adjusts the position of the lens, opening and closing of the iris, and the like. You can focus by shifting the position of the lens. In addition, the amount of light may be adjusted by adjusting the opening and closing of the iris. The optical driver 11 may control the optical unit 10 according to a control signal automatically generated by an image signal input in real time or a control signal manually input by a user's manipulation.

The optical signal transmitted through the optical unit 10 reaches the light receiving surface of the imaging element 15 to form an image of the subject. The imaging device 15 may be a photoelectric conversion device that converts an optical signal into an electrical signal. For example, a charge coupled device (CCD) or a complementary metal oxide semiconductor image sensor (CIS) may be used. Such an image pickup device 15 may be controlled by the image pickup device controller 16. The imaging device controller 16 may also control the imaging device 15 according to a control signal automatically generated by an image signal input in real time or a control signal manually input by a user's operation.

The operation unit 20 is a place that can input a control signal from the outside such as a user. The control unit 20 exposes the image pickup device 15 to light for a predetermined time, and releases a shutter release button for inputting a shutter release signal for taking a picture, a power button input for supplying power, and a wide angle of view according to the input. There are a wide-angle zoom button and a tele-zoom button for increasing or narrowing the angle of view, and various function buttons for selecting a mode such as a text input or shooting mode, a playback mode, a white balance setting function, and an exposure setting function. The operation unit 20 may have the form of various buttons as described above, but is not limited thereto, and may be implemented in any form that a user can input, such as a keyboard, a touch pad, a touch screen, a remote controller, and the like.

The image processing mode selector 21 receives an image processing mode for the captured image from the user. Here, the image processing mode is a mode that expresses the captured image brightly and beautifully. In addition, the user may select the intensity of the image processing, for example, a strong process, an intermediate process, a weak process, and the like through the image processing mode selector 21. Thus, the user can select whether or not to process the image of the portrait photograph and the intensity. Although the image processing mode selection unit 21 has been described separately from the operation unit 20, the above-described functions of the image processing mode selection unit 21 may be performed by the operation unit 20.

The digital photographing apparatus 100 may include a program storage unit 30 for storing a program such as an operating system or an application system for driving the digital photographing apparatus, and a buffer storage unit 40 for temporarily storing data or result data necessary for performing an operation. And a data storage unit 50 for storing various information necessary for the program, including an image file including an image signal.

In addition, the digital camera 100 is a display control unit 60 for controlling to display its operating state or the image information photographed by the digital camera 100, a data driver 61 input from the display control unit 60 to transfer the display data ), And a display unit 65 for displaying a predetermined image according to signals input from the scan driver 63, the data driver 61, and the scan driver 63. The display unit 65 may be formed of a liquid crystal display panel (LCD), an organic light emitting display panel (OLED), an electrophoretic display panel (EDD), and the like.

The digital camera 100 includes a DSP 70 for processing the input image signal and controlling the components according to the input signal or according to the external input signal.

The DSP 70 will be described with reference to FIG. 2 together.

Referring to FIG. 2, the digital signal processor 70 includes a controller 71, an image signal processor 72, a face region detector 73, and a gamma correction controller 74. Here, the digital signal processor and the image processing apparatus used in the claims should be interpreted in the same sense.

The controller 71 controls the overall operation of the digital signal processor 70.

The video signal processor 72 converts the video signal input from the imaging device 15 into a digital signal. In addition, gamma correction is performed to convert an image signal according to the human vision. In addition, image signal processing such as color filter array interpolation, color matrix, color correction, and color enhancement is performed.

In addition, when the function is set, the image signal processor 72 may perform an auto white balance or auto exposure algorithm. In addition, the size of the image data is adjusted using a scaler and compressed to form an image file of a predetermined format. Conversely, image files can be extracted. The image signal processing unit 72 may perform the above image signal processing on the image signal input in real time in the live-view mode before taking a picture and the image signal input by the shutter-release signal. In this case, different video signal processing may be performed on each of the video signals.

In an exemplary embodiment of the present invention, the image signal processor 72 converts the image signal input from the image pickup device 15 into a digital signal and transmits the image signal to the face region detection unit 73. When the face region detector 73 detects a predetermined face region, the face region detector 73 performs an AE operation on the detected face region. Therefore, the brightness of the overall image is made around the face area.

Here, when the AE operation and the function are described, the RGB image signal of the detected face area is integrated and provided to the control unit 71, and the control unit 71 uses the metering and ranging to obtain the average brightness of the face area, that is, the face. The luminance of the area is detected. The control unit 71 then calculates an exposure value suitable for shooting, that is, an EV value. The control unit 71 determines the aperture value (F value) and the shutter speed of the CCD according to a predetermined program based on the EV value to perform AE. Although the above-described AE operation has been described as being performed by the image signal processor 72, it may be performed by a separate AE calculator.

In addition, the image signal processor 72 performs gamma correction, wherein gamma correction means correcting a difference between the brightness of the input image and the brightness of the output image. By adjusting the ratio of values, ie gamma curve. In a preferred embodiment of the present invention, the image signal processor 72 performs gamma correction by correcting a gamma curve under the control of the gamma correction controller 74.

The face area detector 73 detects a face area from an image input through the imaging device 15. Specifically, the face area detection unit 72 detects an area having a feature of the face included in the face, for example, an area having flesh color, an area having pupils, an area having a shape of the face, and the like as the face area.

There are many techniques for face region detection or algorithm, and it can be used for face detection according to a preferred embodiment of the present invention. For example, a face region may be detected using a motion vector technique, a feature point detection technique, an Adaboost learning technique, or the like.

The gamma correction controller 74 outputs a control signal for causing the image signal processor 72 to correct the gamma curve based on the result of the AE calculation of the image signal processor 71. Preferably, the gamma correction controller 74 increases the brightness of the AE target portion, that is, the face region, according to the AE operation. This can increase the brightness of the face area by setting the gamma of the AE target portion high. If the gamma of the face part is set high, the parts having the same brightness as the face area in the entire image are brightened, so that the overall bright image can be obtained.

In addition, the low luminance portion is preferably to maintain the existing gamma curve. This is because a large amount of noise is generated when the gamma of the low luminance portion is increased. Preferably, the contrast of the input image is controlled to a low level. If the overall contrast is lowered, a blurred image appears, so that a smooth and bright image to be achieved in a preferred embodiment of the present invention can be obtained. Here, the high and low degree can be arbitrarily determined according to the degree of the image processing effect. That is, it is not necessary to specify the degree of high and low.

Referring to FIG. 3, the gamma curve 320 before the control of the gamma correction controller 74 and the gamma curve 310 after the control are shown. Here, the horizontal axis is the luminance value of the input image and the vertical axis is the luminance value of the output image. Reference numeral 340 denotes an AE target level according to an AE operation of the image signal processor 72. As shown in the figure, it can be seen that the AE target of the gamma curve 320 before the control and the AE target of the gamma curve 310 after the control are increased. Therefore, the gamma curve near the AE target level, i.e., the luminance value in the detected face region, becomes high and the brightness of the face region becomes bright. The brightness of the part in the same brightness band as the brightness value of the face area is also brightened, so that the overall brightness of the image can be brightened.

4 is a flowchart illustrating an image processing method according to another exemplary embodiment.

Referring to FIG. 4, in step 400, an image processing mode is selected. In this case, the image processing mode refers to processing that makes an image softer and brighter than an original image. In operation 402, it is determined whether a face region is detected in an input image. If the face area is detected, the process proceeds to step 404 to perform an AE operation around the detected face area. In step 406, based on the AE calculation result, the gamma curve in the AE target portion is corrected. Preferably, since the AE target portion is the face region, it is desirable to increase the brightness for this portion. In other words, by increasing the gamma curve for the face part, the area of the face and the surrounding areas having similar brightness are equally brightened. Therefore, it is possible to produce a bright and bright image for the overall image.

Also, optionally, the gamma curve of the low luminance band is kept equal to the existing gamma. This is because a lot of noise may occur when the gamma of the low luminance band is increased.

The above embodiments have been described with reference to a digital camera as an example of a digital photographing apparatus to which the present invention can be applied, but is not limited thereto. Those skilled in the art will appreciate that the present invention can be applied to camera phones, personal digital assistants (PDAs), and portable multimedia players (PMPs) with added camera functionality.

Meanwhile, the present invention can be embodied as computer readable codes on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored.

Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disks, optical data storage devices, and the like, which are also implemented in the form of carrier waves (for example, transmission over the Internet). It includes. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. And functional programs, codes and code segments for implementing the present invention can be easily inferred by programmers in the art to which the present invention belongs.

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will understand that the present invention can be embodied in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown not in the above description but in the claims, and all differences within the scope should be construed as being included in the present invention.

1 is a schematic block diagram of a digital photographing apparatus 100 according to an exemplary embodiment.

FIG. 2 is a block diagram of the digital signal processor 70 shown in FIG. 1.

3 is a diagram for describing gamma curve correction according to another exemplary embodiment of the present invention.

4 is a flowchart illustrating an image processing method according to another exemplary embodiment.

<Explanation of symbols for the main parts of the drawings>

21: image processing mode selection unit 70: digital signal processing unit

71: control unit 72: image signal processing unit

73: face area search unit 74: gamma correction control unit

Claims (13)

(a) detecting a predetermined face area in the input image; (b) performing an AE operation around the detected face area; And (c) controlling to correct a gamma curve based on the result of the AE operation. The method of claim 1, In step (c), And controlling to correct a gamma curve of the AE target portion. The method of claim 2 In step (c), And controlling gamma of the AE target portion to a high level. The method of claim 3, wherein In step (c), And controlling the contrast of the input image to a low level. The method of claim 3, wherein Before step (a) above, The image processing method further comprises the step of selecting an image processing mode for the input image. The method of claim 1, In the step (a), And performing steps (b) to (c) when at least one face area is detected in the input image. A recording medium having recorded thereon a program for executing a method according to any one of claims 1 to 6 on a computer. A face region detector for detecting a predetermined face region in the input image; An image signal processor which performs an AE operation based on the detected face region; And And a gamma correction controller configured to control the image signal processor to correct a gamma curve based on the AE calculation result. The method of claim 8, The gamma correction control unit, And control to correct a gamma curve of the AE target portion. The method of claim 9, The gamma correction control unit, And controlling gamma of the AE target portion to a high level. The method of claim 11, The gamma correction control unit, And control the contrast of the input image low. The method of claim 8, And an image processing mode selector configured to select an image processing mode for the input image. A digital photographing apparatus comprising the image processing apparatus according to any one of claims 8 to 12.

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