KR20090080610A - Intelligent flash device and method of digital imaging device - Google Patents

Abstract

The present invention relates to a flash device and a method of a digital imaging device, and in order to express the light quality of a photographed image to a photographic expert level, an analysis of reflection characteristics of an illumination distribution or an object in a scene based on an image and the result of the analysis It is characterized by adjusting the irradiation angle or the light emission amount of the flash. According to this, when there is a quality deterioration factor in the captured image, the irradiation angle or the light emission amount of the flash is adaptively adjusted to obtain a high quality image.

Description

An intelligent flash apparatus of digital imaging device and flash methods

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flash mounted on an imaging device, and more particularly, to an intelligent flash device and a method of a digital imaging device capable of expressing light quality at an expert level.

A digital imaging device generally refers to a device that digitalizes photographing information and displays or stores it to a user, such as a digital camera or a web camera. In recent years, along with the consumer desire to express themselves and the development of information and communication technology, many of these digital imaging devices have become popular. For example, in the case of a personal digital camera, its use has been generalized in place of an existing film camera because a separate development process is not required and a lot of effort is not required to modify or store a captured screen.

In addition, the digital imaging device is generally provided with a flash device for irradiating light to the subject. Especially when shooting a subject, the flash around the subject plays an important role in determining the quality of the screen, so this flash is often used in conjunction with digital imaging equipment. In addition, as users' desire to capture high-definition images such as photographic professionals increases, expensive flashes used in DSLR cameras have emerged.

However, in the case of automatic shooting in a poor shooting environment, the parameters set by the developers of the camera set are often different from those of the general users, so that the majority of users are not satisfied with the captured pictures or have difficulty in shooting. There is a problem.

In particular, the conventional flash is not precisely adjusted according to the characteristics of the subject in the room, night view, backlight environment, the quality of the light deterioration factors such as excessive reflection or surface bundling often occurs. In addition, when the main light and the auxiliary light are present in the scene at the same time, it is difficult to control the flash without professional shooting knowledge.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems. In order to provide a high-quality image of a photographic expert, a digital imaging device for analyzing a photo quality characteristic of a scene based on an image and adaptively adjusting a flash according to the analysis result Relates to a flash device and a method thereof.

Specifically, the flash device of the digital imaging device according to the present invention, the image analysis unit for analyzing the light quality characteristics of the preview image of the digital imaging device; And a flash controller configured to adjust a light emission amount or an irradiation angle of a flash provided in the digital imaging apparatus according to the analysis result of the image analyzer.

In this case, the image analyzer may analyze the illumination distribution of the scene by dividing the preview image into a plurality of windows and calculating an average luminance value of each window. The image analyzer may analyze reflection characteristics of the subject through color space conversion that converts RBG data of the preview image into luminance / illuminance / reflectance data.

In addition, the flash controller may partially adjust the amount of light emitted from the flash so that a soft light quality is expressed when multiple light sources are detected in the preview image of the image analyzer. In this case, the flash may use an array light source type flash in which a plurality of light emitting elements are uniformly arranged.

The flash controller may adjust the irradiation angle of the flash so that no direct reflection occurs when the reflector is detected in the preview image of the analysis result of the image analyzer.

On the other hand, the flash method of the digital imaging device according to the present invention comprises the steps of analyzing the preview image of the digital imaging device to determine the light quality characteristics of the preview image; And adjusting an amount of light emitted or an irradiation angle of a flash provided in the digital imaging device according to the identified light quality characteristic.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention; In the following description of the present invention, if it is determined that detailed descriptions of related well-known functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. In addition, terms to be described below are terms defined in consideration of functions in the present invention, and may vary according to a user, an operator's intention, or a custom. Therefore, the definition should be made based on the contents throughout the specification.

1 illustrates the overall configuration of an intelligent flash device of a digital imaging device according to an embodiment of the present invention.

Referring to FIG. 1, an intelligent flash apparatus of a digital imaging apparatus according to an exemplary embodiment of the present invention includes an image analyzer 101 and a flash controller 102.

The image analysis unit 101 is a part of analyzing the light quality characteristic of the preview image of the digital imaging device. Here, the digital imaging device refers to a photographing apparatus that digitizes photographing information and displays or stores it to a user, such as a digital camera embedded in a personal digital camera or a mobile phone. The digital imaging apparatus generally includes various optical lenses, image sensors, digital signal processing apparatuses, and the like for digitally processing photographing information. For example, as shown in FIG. 1, the digital imaging apparatus includes a lens unit 103, an image sensor unit 104, an image processing unit 105, an image display unit 106, a 3A parameter generating unit 107, and a lens control unit 108. ), Flash 109, and the like.

In FIG. 1, the lens unit 103 transmits the light reflected from the subject to the image sensor unit 104. When the user photographs an arbitrary subject, the light reflected from the subject is transferred to the image sensor unit 104. It may be composed of a plurality of optical lenses, apertures, and the like so as to properly form an image.

The image sensor unit 104 converts the formed light into an electrical signal, and a solid state imaging device such as a CCD or a CMOS image sensor may be used.

The image processing unit 105 receives an electrical signal from the image sensor unit 104 and processes the image so as to be displayed on the image display unit 106 or stored in a separate storage unit (not shown).

The 3A parameter generator 107 classifies scenes according to a predefined criterion for generating high quality images, generates a control parameter most suitable for each scene, and applies the lens parameter to the lens controller 108. For example, the 3A parameter generator 107 generates a parameter for adjusting auto exposure (AE), auto white balance (AWB), auto focus (AF), and the like, and applies the parameter to the lens controller 108 so that the shutter speed, the lens, It is possible to adjust the aperture, the focus lens and the like.

When the user wants to shoot a specific object, the preview image appearing on the image display unit 106 determines the shooting composition, and then the actual image is taken. The image interpreter 101 displays the preview image on the image display unit 106. It is to analyze whether the deterioration factors such as excessive reflection or light blur on the screen before shooting.

For example, the image analysis unit 101 may analyze the illumination distribution of the scene or the reflection characteristic of the subject with respect to the preview image. At this time, the illumination distribution of the scene is a concept that includes the number and distribution of the main light source of the scene, the reflection characteristics of the subject includes the brightness, illuminance or reflectance of the surface of the subject. As an analysis method of the light quality characteristic, an image-based scene analysis technique such as color space conversion and luminance intensity calculation may be used.

The flash controller 102 adjusts the light emission amount or the irradiation angle of the flash 109 provided in the digital imaging apparatus according to the analysis result of the image analyzer 101.

For example, when multiple light sources are detected in the preview image of the image analyzing unit 101, it is possible to partially adjust the light emission amount of the flash 109 so that a soft light quality is expressed. In addition, when the reflector is detected in the preview image, the irradiation angle of the flash 109 may be adjusted so that no direct reflection occurs. To this end, the flash 109 may have a configuration as shown in FIG. 2.

2 illustrates a configuration of a flash according to an embodiment of the present invention.

Referring to FIG. 2, the flash 109 according to the embodiment of the present invention has a structure in which light emitting devices 202 such as LEDs are uniformly arranged on a plane, and the top / bottom Θ / It is comprised so that rotation to left and right (alpha) is possible.

Accordingly, when the flash controller 102 partially adjusts the light emission amount of the flash 109, the light emission elements 202 may be independently controlled to partially adjust the overall light emission amount. In addition, the flash control unit 102 may adjust the direction of light emitted from the flash 109 and irradiated to the subject by rotating the rotating shaft 201 or the head.

3 is an example illustrating a case where a light emission amount of a flash is partially adjusted according to an illumination distribution.

1 and 3, in detail, in FIG. 1, the image interpreter 101 analyzes an illumination distribution and the number of preview images to determine whether there are multiple light sources. The method of inferring whether the image interpreter 101 is meaningful as a light source for improving image quality may be performed by the following method.

For example, the image analysis unit 101 divides the preview image into M × N sub-windows, calculates an average luminance value of each window, and detects the window area as a light source when the average luminance value is larger than a preset threshold. It is possible to do

In another method, the average luminance intensity of each window is calculated in a uniform color space and a cumulative density probability is calculated based on the average luminance intensity of each window. It is possible to detect the statistically significant level of the number of meaningful illumination and the spatial position by dividing the local variance cumulative probability distribution into L levels and analyzing each level for each region.

When multiple light sources are detected by the image analyzing unit 101, the flash controller 102 partially adjusts the light emission amount of the flash 109. For example, as shown in FIG. 3, it is possible for the flash control unit 102 to individually adjust each light emitting device 202 to partially adjust the light emission amount of the flash 109. For example, the amount of light emitted from the light emitting device 202 present at the (n, m) coordinates may be adjusted using the following equation.

In Equation 1, I _{n , m} denotes the n, m th flash light quantity, I _a denotes the maximum light intensity of all flashes, S _a denotes the total image intensity, and S _{n , m} denotes the image intensity of the N, Mth window. Respectively, and the illuminance function f may be expressed as shown in the graph of FIG. 3.

As such, when there are multiple light sources in the scene, it is possible to soften the overall light texture by adjusting the partial light emission amount of the flash. This can produce a visual effect similar to the light-assisted softbox used by photography professionals.

4 illustrates an example in which an irradiation angle of a flash is adjusted according to a reflection characteristic of a subject. Looking at this in detail with reference to Figures 1 and 4 as follows.

4 shows that the irradiation angle of the flash 109 is adjusted so that no direct reflection occurs when the reflector 401 is detected on the object surface.

To this end, in FIG. 1, the image analyzer 101 analyzes luminance, illuminance, or reflectance of a surface of a subject existing in a scene. For example, the image analyzer 101 may convert RGB data of the preview image into luminance, illuminance, or reflectance data through color space conversion.

The matrix coefficient for the color space transformation may be derived as follows, but is not necessarily limited thereto, and of course, a color space transformation technique may be used.

For example, the image analysis unit 101 creates a sensor response model using RGB data of the preview image, reconstructs the sensor response model using a Dirac delta function, and then performs black body radiation. It is possible to derive coefficients through PCA (pricipal component analysis) method by estimating roughness based on this and taking a log to it.

In Equation 2, P ₀ , P ₁ , and P ₂ represent R signals, G signals, and B signals, respectively, and L, I, and r represent luminance, illuminance, and reflectance corresponding to RGB information. reflectance factor), and a denotes matrix coefficients for color space conversion.

To derive the coefficients for color space conversion, we construct the response model that accepts the RGB data and the sensor and reconstruct the response model using the delta delta function.

In Equation 3, E denotes an illumination spectral power distribution, S denotes a surface reflectance fuction, and R denotes a sensor sensitivity.

In Equation 3, roughness is estimated for the E function based on a black body radiator as follows.

In Equation 4, I denotes a power of illumination, T denotes a color temperature of a black body, and C denotes a constant.

Substituting the above equation into the initially constructed response model and taking a log, we can use the PCA (principal component analysis) technique to obtain the values of luminance, illuminance and reflectance as follows.

In Equation 5, the first term is related to the intensity of illuminance, the second term is related to reflectance, and the third term is a function related to illuminance. In addition, the fourth term is associated with the sensor as a constant, and the last term is used to determine the gray color when the reflectivity is zero.

That is, it is possible to analyze the luminance, illuminance, reflectance, etc. of the surface of the subject existing in the preview image by the above-described method, and to determine that the surface of the subject having the reflectance above a specific threshold is a reflector.

For example, as shown in FIG. 4, when a specific part of the subject is detected by the reflector 401, the flash controller 102 may change the irradiation angle so that direct reflection does not occur by driving the rotating shaft or the head of the flash 109. Do.

Next, an intelligent flash method of a digital imaging device according to an embodiment of the present invention will be described with reference to FIG. 5.

In an intelligent flash method of a digital imaging device according to an embodiment of the present invention, first, a light quality characteristic of a preview image of the digital imaging device is determined (S501).

Here, the preview image refers to a screen before shooting, which is displayed through the display unit of the digital imaging device, and the user starts to view the preview image. Therefore, the scene to be photographed appears in the preview image. The light quality characteristic may refer to a texture of light appearing in the preview image, and may include an illumination distribution of a scene or a reflection characteristic of a subject with respect to the preview image.

This optical quality characteristic is analyzed by the image analysis unit 101 to divide the preview image into a plurality of windows and to calculate the average luminance value for each window to analyze the lighting distribution of the scene, or to convert the luminance of the RBG data through color space conversion It is possible to analyze the reflection characteristics of the subject by converting it into illuminance or reflectance data.

When the light quality characteristic of the preview image is determined, the light emission amount or the irradiation angle of the flash included in the digital imaging apparatus is adjusted according to the identified light quality characteristic (S502).

To this end, the flash may be configured as shown in FIG. 2, and the flash controller 102 may adjust the light emission amount or the irradiation angle of the flash.

For example, when multiple light sources exist in the preview image, the flash control unit 102 may partially adjust the light emission amount of the flash 109 so that a soft light quality is expressed. In addition, when the reflector is present in the preview image, the flash controller 102 may adjust the irradiation angle of the flash 109 so that the direct reflection does not occur.

As a result, according to the above-described embodiment, when a deterioration factor such as excessive reflection or light bleeding occurs in a special shooting environment such as indoors, night scenes, or backlighting, the scene is interpreted based on an image and the flash is adjusted using the image. As a result, the quality of the scene can be expressed professionally.

While the embodiments of the present invention have been described above, the present invention is not limited to the above-described specific embodiments. That is, those skilled in the art to which the present invention pertains can make many changes and modifications to the present invention without departing from the spirit and scope of the appended claims, and all such appropriate changes and modifications are possible. Equivalents should be considered to be within the scope of the present invention.

1 is a view showing the overall configuration of a flash device of a digital imaging device according to an embodiment of the present invention;

2 is a view showing the configuration of a flash according to an embodiment of the present invention;

3 is a view showing that the light emission amount of the flash is partially adjusted according to an embodiment of the present invention,

4 is a view showing that the irradiation angle of the flash is adjusted according to an embodiment of the present invention,

5 is a flowchart illustrating a flash method of a digital imaging device according to an embodiment of the present invention.

<Description of Major Symbols in Drawing>

101: video analysis unit

102: flash control unit

103: lens unit

104: image sensor

105: image processing unit

106: image display unit

107: 3A parameter generator

108: lens control unit

109 flash

Claims (13)

Image analysis unit for analyzing the light quality characteristics of the preview image of the digital imaging device; And And a flash controller configured to adjust an emission amount or an irradiation angle of a flash provided in the digital imaging device according to an analysis result of the image analyzer. The method of claim 1, And the image analyzer divides the preview image into a plurality of windows and calculates an average luminance value of each window to analyze an illumination distribution of a scene. The method of claim 1, And the image analyzer converts RBG data of the preview image into luminance, illuminance, or reflectance data through color space conversion to analyze reflection characteristics of a subject. The method of claim 1, And the flash controller partially adjusts the amount of light emitted from the flash to display a soft light quality when multiple light sources are detected in the preview image as a result of analysis of the image analyzer. The method of claim 1, And the flash controller adjusts an irradiation angle of the flash so that no direct reflection occurs when a reflector is detected in the preview image as a result of analyzing the image interpreter. The method of claim 1, The flash is an intelligent flash device of a digital imaging device is an array light source type flash in which a plurality of light emitting elements are uniformly arranged. The method of claim 2, And the illumination distribution of the scene includes the number and distribution of main light sources present in the preview image. The method of claim 3, wherein And the reflection characteristic of the subject includes luminance, illuminance, or reflectance of the surface of the subject existing in the preview image. (a) analyzing the preview image of the digital imaging device to determine a light quality characteristic of the preview image; And and (b) adjusting the light emission amount or the irradiation angle of the flash provided in the digital imaging device according to the light quality characteristic. The method of claim 9, The step (a) comprises dividing the preview image into a plurality of windows and analyzing the illumination distribution of the scene using the average luminance value for each window. The method of claim 9, The step (a) comprises the step of converting the RBG data of the preview image into luminance / illuminance / reflectance data through color space conversion to analyze the reflection characteristics of the subject. The method of claim 9, The step (b) of the intelligent imaging method of the digital imaging device comprising the step of partially adjusting the amount of light emitted from the flash so that a smooth light quality is expressed when there are multiple light sources in the preview image. The method of claim 9, And (b) adjusting the irradiation angle of the flash so that no direct reflection occurs when the reflector is present in the preview image.

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