TWI405458B - Digital camera sensitivity adjustment method - Google Patents

Abstract

A method for adjusting photo-sensitiveness is able to determine a relative distance of an object in an image capture area through images captured before and after the pre-flash of a flash lamp, so that the relative distance serves as a reference for adjusting current photo-sensitiveness of the digital camera, thereby capturing an image having a better quality when the flash lamp provides a fill light. The digital camera comprises a flash lamp and a photographing module. The method for adjusting photo-sensitiveness of a digital camera comprises: capturing a live view image corresponding to a plurality of objects by the photographing module; enabling the flash lamp to emit a pre-flash light, and capturing a pre-flash image corresponding to the objects by the photographing module; calculating a reflection image through the live view image and the pre-flash image; judging appearance positions of the objects in the pre-flash image through reflection information of all position points on the reflection image; performing a recognition procedure according to the appearance positions, so as to find image information that presents the objects in the pre-flash image; determining whether the objects are at more than two different depths of field (DOFs) according to the image information of the objects; and when the objects are at more than two different DOFs, adjusting current photo-sensitiveness of the photographing module.

Description

Method for adjusting the sensitivity of a digital camera

The invention relates to a method for adjusting imaging parameters of a digital camera, in particular to a method for adjusting the sensitivity of a digital camera.

With the development of digital cameras, photography is no longer an expensive purchase. The user can take the desired image at will to record a memorable moment or scene.

When shooting, the average user wants the captured photo to be clearly visible. Therefore, when shooting a target (which can be a landscape, a person, or an item), adjust the focus and brightness of the target to be able to take a satisfactory picture.

With the advancement of technology, digital cameras mostly provide the function of automatically setting camera parameters. In general, a digital camera calculates appropriate imaging parameters for a target.

Among them, the amount of light emitted by the digital camera's flash can be adjusted according to the distance between the digital camera and the target.

The relationship between the flash intensity of the flash and the distance of the target and the aperture coefficient value can be expressed as: GN = f × L. Where GN represents the flash intensity (ie, the flash index GN, Guide Number), f is the aperture coefficient, and L is the distance between the target and the digital camera. The flash index is a measure of the luminous intensity of a flash and is a major basic indicator of flash performance.

In the shooting range of a digital camera, there are usually multiple objects. In general, digital cameras use one of the targets as a target. Since the digital camera fills the target while shooting, the image of the target that is farther away from the digital camera is more blurred and/or the brightness is relatively dark relative to the target.

In view of the above problems, the present invention provides a method of adjusting the sensitivity of a digital camera by solving at least one of the problems of the prior art.

The method for adjusting the sensitivity of the digital camera disclosed in the present invention is applied to a digital camera. The digital camera includes a flash and a camera module.

First, the camera module captures a preview image corresponding to the plurality of objects. Then, the flash is caused to emit a pre-flash, and the camera module is used to capture a pre-flash image corresponding to the objects. Then, a reflected image is calculated through the preview image and the pre-flash image, and the display position of the target object in the pre-flash image is discriminated by the reflection information of each position point on the reflected image. And performing an identification process on the obtained display position to find the image information of the target object in the pre-flash image, and determining whether the target objects belong to two or more different depth of fields according to the image information of the found target object. .

When the target objects belong to more than two different depth of field, adjust the current sensitivity of the camera module. After adjusting the current sensitivity of the camera module, the flash can be pre-flashed again, and the pre-flash image of the target object is captured again by the camera module as a reference for other camera parameters.

When the objects in front of the digital camera belong to the same depth of field, the current sensitivity of the camera module is not adjusted, and the flash intensity of the main flash is calculated from the pre-flash image.

Wherein, each object can be a face, and the identification program can be a face recognition program.

Here, the reflected image can be obtained by comparing the brightness information of the preview image with the brightness information of the pre-flash image.

In the sensitivity adjustment, the sensitivity of the camera module can be directly increased to twice the current sensitivity. Furthermore, it can also be adjusted according to the setting option of the sensitivity of the camera module or the specific target.

The method for adjusting the sensitivity of the digital camera according to the present invention can determine the relative distance of the target object in the image capturing range by using the image obtained by the flash before and after the pre-flashing, as a reference for adjusting the current sensitivity of the digital camera. In addition, a better quality image can be captured while the flash is being filled.

The above description of the present invention and the following description of the embodiments of the present invention are intended to illustrate and explain the spirit and principles of the invention.

In this manner, the method for adjusting the sensitivity of the digital camera according to the present invention can determine the relative distance of the target object in the image capturing range by performing the image (preview image and pre-flash image) acquired before and after the pre-flash. As a reference for adjusting the current sensitivity of the digital camera, it is possible to capture a better quality image while the flash is being filled.

Referring to FIG. 1 , the digital camera 100 may include a camera module 110 , a flash 120 , a storage unit 130 , a processing unit 140 , and a display 150 . The camera module 110 includes a lens group 112 and a photosensitive element 114.

The operation of the digital camera 100 can be divided into a live view, an auto focusing, a pre-flash phase, and a shooting phase.

The preview phase refers to the time before the user presses the shutter button of the digital camera 100. In the preview phase, the user can preview the viewfinder through the display 150 of the digital camera 100.

The focus phase refers to the moment when the user presses the shutter button of the digital camera 100 halfway. In the focusing phase, the digital camera 100 takes one or more of the objects in the framing picture as the target, and adjusts the object distance between the lens group 112 and the target, and the user can preview through the display 150 of the digital camera 100. The framing screen after focusing (ie, after the object distance adjustment is completed).

The pre-flash phase means that the flash 120 emits a pre-flashing light after focusing, and the digital camera 100 captures an image corresponding to the current viewing frame through the camera module 110 as a reference for the flash intensity of the shooting phase.

The shooting phase refers to the moment when the user fully presses the shutter button of the digital camera 100. During the shooting phase, the digital camera 100 captures the current viewfinder image through the camera module 110 and records the captured viewfinder image as an image.

Here, the preview image is an image captured by the index camera 100 during the preview phase or the focusing phase. The pre-flash image is the image captured by the index camera 100 during the pre-flash phase.

The lens group 112 is used to adjust the focal length of the subject.

The photosensitive element 114 is provided corresponding to the lens group 112. The photosensitive element 114 can receive the optical signal corresponding to the target and its surrounding scenery through the lens group 112, and convert the received optical signal into the electrical signal of the digital image to obtain an image corresponding to the target. In other words, the photosensitive element 114 can capture the preview image via the lens group 112 during the preview phase and the focusing phase of the digital camera 100, capture the pre-flash image through the lens group 112 during the pre-flash phase of the digital camera 100, and the digital camera 100 The digital image is captured through the lens group 112 during the shooting phase.

The processing unit 140 is electrically connected to the photosensitive element 114 and the storage unit 130. The processing unit 140 can control the operation of the lens group 112 and the photosensitive element 114. Moreover, the processing unit 140 can determine the distance between each target object in front of the digital camera 100 according to the captured preview image and the pre-flash image, thereby selectively adjusting the current sensitivity of the digital camera.

In other words, the method of adjusting the sensitivity of the digital camera according to the present invention can be implemented on the digital camera 100 in a software or firmware program. That is, one of the codes for adjusting the sensitivity of the digital camera according to the present invention may be stored in the storage unit 130 of the digital camera 100, and the processing unit 140 of the digital camera 100 reads and executes the stored code. In order to cause the digital camera 100 to perform the adjustment method of the sensitivity of the digital camera according to the present invention, the sensitivity thereof is selectively adjusted.

The processing unit 140 can be implemented by one or more processors, such as a digital signal processor (DSP). The storage unit 130 can be implemented by one or more storages. The reservoir can be non-volatile memory or volatile memory.

Fig. 2 is a flow chart showing a method of adjusting the sensitivity of a digital camera according to an embodiment of the present invention.

Referring to "1st and 2nd views", first, a preview image corresponding to a plurality of objects in front of the digital camera 100 is captured by the camera module 110 (step 210).

Then, the flash 120 is caused to emit a pre-flash, and a pre-flash image corresponding to the objects is captured by the camera module 110 under the pre-flashing fill light (step 220).

A reflected image is calculated from the captured preview image and the pre-flash image (step 230). In this case, the reflected image can be obtained by comparing the brightness information of the preview image with the brightness information of the pre-flash image. In other words, the reflected image is the difference between the brightness information corresponding to the preview image and the brightness information of the pre-flash image.

The appearance position of the object in the pre-flash image is discriminated by the reflection information of each position point on the reflected image (step 240). That is to say, the block of the image of the pre-flash image that may belong to the target object can be discriminated by observing the reflection information of each position point on the reflected image. The reflection information may be the amount of reflection (ie, the difference between the brightness information of the preview image and the same position of the pre-flash image) or the reflectance. Each location point can be one pixel or a specific size image block.

An identification process is performed for determining the appearance position to find image information of the object in the pre-flash image (step 250). In other words, the identification program is used to identify the target image on the local image of the pre-flash image to find the image block (ie, image information) belonging to the target object.

It is judged based on the image information of the found object that the object belongs to two or more different depths of field (step 260). Here, by calculating the image information of the object, it can be known whether the plurality of objects in front of the digital camera 100 fall on two different focusing ranges of the digital camera 100.

When the subject matter in front of the digital camera 100 belongs to two different depths of field, the current sensitivity of the camera module 110 is adjusted (step 270) to increase the brightness of the image of the object located at a relatively distant object. That is, when a plurality of objects in front of the digital camera 100 fall on two different focus ranges of the digital camera 100, the digital camera 100 adjusts the current sensitivity to take into account relatively distant objects. Brightness.

Moreover, after adjusting the current sensitivity of the camera module 110, the flash 120 can be caused to emit pre-flashing again, and the pre-flash image of the target object is captured again by the camera module 110 as a reference for other imaging parameters (step 280). ). For example, the flash intensity of the main flash can be calculated from the pre-flash image acquired again (step 290).

When the objects in front of the digital camera 100 all belong to the same depth of field, the current sensitivity of the camera module 110 is not adjusted, and the flash intensity of the main flash is calculated as the pre-flash image (step 290).

At the time of shooting, the flash 120 emits a main flash having a calculated flash intensity, and the camera module 110 captures the digital image of the subject.

Among them, the subject matter can be a face, and the recognition program is a face recognition program. However, this is not a limitation of the present invention. The subject matter may be set as at least one characteristic object of a face, a building, an animal, a plant, a vehicle, a sign, and a specific item according to actual needs.

Referring to "Fig. 3", in step 240, a first threshold value can be used to compare the reflection information at each of the position points on the reflected image (step 241).

When the reflection information is greater than the first threshold, the corresponding position point (ie, the position point whose reflection information is greater than the threshold value) is determined as the appearance position of the target object (step 242).

When the reflection information is less than or equal to the first threshold value, the corresponding position point (ie, the position point whose reflection information is less than or equal to the threshold value) is determined as the display position of the target object (step 243).

Referring to FIG. 4, in step 260, the reflection information corresponding to the image information of the found object can be compared with each other (step 261), and the comparison result is compared with a second threshold (step 262). . In this case, the reflection information corresponding to the image information of any two objects can be compared with each other to obtain the result of comparing all the objects. Alternatively, the reflection information corresponding to the image information of the target object focused by the camera module 110 is compared with the reflection information corresponding to the image information of the other target objects.

When the difference of the reflection information corresponding to the two objects (ie, the comparison result) is greater than the second threshold, it is determined that the plurality of objects in front of the digital camera 100 belong to two or more different depths of fields (step 263).

When the difference of the reflection information corresponding to all the two objects (ie, the comparison result) is less than or equal to the second threshold, it is determined that the plurality of objects in front of the digital camera 100 belong to a single depth of field (step 264).

Here, the face is described as a subject. Referring to "figure 5", the image blocks A, B, C, and D in the image belong to four objects. The same image block A/B/C/D in the preview image and the pre-flash image will be in the same relative position.

Compared with the image block E belonging to the non-standard object (for example, the background), the brightness information of the image block A/B/C/D of the target object in the preview image is the same as that in the pre-flash image. The difference between the brightness information of A/B/C/D is relatively large. In other words, the change between the brightness information in the preview image and the brightness information in the pre-flash image of the same image block A/B/C/D relative to the image block E of the non-standard object (eg, background) (difference) ) Larger. Therefore, comparing the reflection information of each position point in the reflected image with the second threshold value, the position of the reflection information greater than the second threshold value can be found to obtain the image blocks A, B, C, and D. position. Further, a face recognition program is performed for the found position to determine image blocks A, B, C, and D (ie, four faces).

Then, the brightness information of the image blocks A, B, C, and D is compared to determine whether the image blocks A, B, C, and D are in different depth of field.

For example, the brightness information of the image blocks A, B, C, and D can be compared to each other to obtain the difference between the brightness information of the image blocks A and B, and the difference between the brightness information of the image blocks A and C. The difference between the value, the brightness information of the image blocks A and D, the difference of the brightness information of the image blocks B and C, the difference between the brightness information of the image blocks B and D, and the brightness of the image blocks C and D. The difference in information. The resulting six differences are then compared to a second threshold to determine if there is a difference greater than the second threshold. If the difference is greater than the second threshold, it means that the image blocks A, B, C, and D belong to two or more different depths of field. In the "figure 5", the image blocks A, B, C, and D belong to three different depths of field. That is, the image block A and the other three (image blocks B, C, D) belong to different depths of field, and the image block D also has different depth of field from the other three (image blocks A, B, C).

In another embodiment, if the digital camera 100 is focused on the target object corresponding to the image block D, the brightness information of the image block D is compared with the other three (image blocks A, B, and C). In order to obtain the difference between the brightness information of the image blocks D and A, the difference between the brightness information of the image blocks D and B, and the difference between the brightness information of the image blocks D and C. The resulting three differences are compared to a second threshold to determine if there is a difference greater than the second threshold. If the difference is greater than the second threshold, it means that the image blocks A, B, C, and D belong to two or more different depths of field.

In step 270, when the subject matter in front of the digital camera 100 is determined to belong to two different depths of field, the sensitivity of the camera module 110 can be directly increased to twice the current sensitivity. Furthermore, it is also possible to select an adjustment according to the setting option of the sensitivity of the camera module 110 or a specific target.

In the adjustment according to the setting option of the sensitivity of the camera module 110, when it is determined that the subject matter in front of the digital camera 100 belongs to two different depths of field, the setting options of the sensitivity of the camera module 110 may be sequentially The current sensitivity is increased by one level. For example, assume that the sensitivity settings of the camera module 110 provided by the digital camera 100 are 50, 100, 200, 400, 800, and 1600, and the current sensitivity is set to 100. When it is determined that the subject matter in front of the digital camera 100 belongs to two different depths of field, the sensitivity of the camera module 110 is increased from 100 to 200.

According to the specific target, one or more of the objects in the front of the digital camera 100 can be selected as a reference for calculating the adjustment value, and then the current adjustment of the camera module 110 is adjusted with the calculated adjustment value. Sensitivity.

Among them, the object with the deepest depth of field can be selected as a reference for calculating the adjustment value, that is, the adjustment value of the sensitivity is calculated from the image information of the object with the deepest depth of field.

Alternatively, the target object other than the target object may be selected as a reference for calculating the adjustment value, that is, the adjustment value of the sensitivity is calculated based on the image information of the target object falling in the depth of field other than the depth of field in which the camera module 110 is focused. Here, the image information of the object whose depth of field is larger than the depth of field of the target object can be selected to calculate the adjustment value of the sensitivity.

In the case of the object shown in "Fig. 5", it is assumed that the subject matter is a human face and the digital camera 100 is focused on the object corresponding to the image block D. At this time, the image information of the image block A can be selected to calculate the sensitivity adjustment value, or the image information of one or two image blocks of the image blocks A, B, and C can be selected to calculate the sensitivity adjustment value.

In the above description, "first" and "second" are used only to identify two elements (two thresholds), and are not intended to limit the specific elements or order.

Although the present invention has been disclosed above in the foregoing embodiments, it is not intended to limit the invention. It is within the scope of the invention to be modified and modified without departing from the spirit and scope of the invention. Please refer to the attached patent application for the scope of protection defined by the present invention.

100. . . Digital camera

110. . . Camera module

112. . . Lens group

114. . . Photosensitive element

120. . . flash

130. . . Storage unit

140. . . Processing unit

150. . . monitor

A. . . Image block

B. . . Image block

C. . . Image block

D. . . Image block

E. . . Image block

Figure 1 is a schematic diagram of a digital camera in accordance with the present invention.

2 is a flow chart showing a method of adjusting the sensitivity of a digital camera according to an embodiment of the present invention.

FIG. 3 is a detailed flow diagram of step 240 in accordance with an embodiment of the present invention.

Figure 4 is a detailed flow diagram of step 260 in accordance with an embodiment of the present invention.

Fig. 5 is a schematic diagram of a view screen according to an embodiment of the present invention.

Claims (10)

A method for adjusting the sensitivity of a digital camera, the digital camera includes a flash and a camera module, and the method for adjusting the sensitivity of the digital camera comprises: using the camera module to capture a preview image corresponding to the plurality of objects Causing the flash to emit a pre-flash, and using the camera module to capture a pre-flash image corresponding to the objects; calculating a reflected image through the preview image and the pre-flash image; The reflection information of each of the position points determines the appearance position of the objects in the pre-flash image; and performs an identification process for the display positions to find image information of the target objects in the pre-flash image; Determining, according to the image information of the objects, whether the objects belong to two or more different depth of field; and adjusting the current sensitivity of the camera module when the objects belong to two or more different depths of field degree. The method for adjusting the sensitivity of the digital camera according to claim 1, wherein each of the target objects is a human face, and the identification program is a face recognition program. The method for adjusting the sensitivity of the digital camera according to claim 1, wherein the step of calculating a reflected image through the preview image and the pre-flash image comprises: comparing brightness information of the preview image with brightness of the pre-flash image Information to obtain the reflected image, wherein the reflected image is a difference between brightness information corresponding to the preview image and brightness information of the pre-flash image. The method for adjusting the sensitivity of the digital camera according to claim 1, wherein the step of discriminating the appearance positions of the objects in the pre-flash image by using the reflection information of each position point on the reflected image comprises: The reflection information is compared with a threshold value; when the reflection information is greater than the threshold value, the corresponding position point is determined as the appearance position of the target objects; and when the reflection information is less than or equal to the threshold value, corresponding The position point determination is not the appearance position of the objects. The method for adjusting the sensitivity of the digital camera according to claim 1, wherein the step of determining, according to the image information of the objects, whether the objects belong to two or more different depths of field comprises: The reflection information corresponding to the image information of the object is compared with each other; and when the difference between the reflection information corresponding to the two objects in the object is greater than a threshold, determining that the objects belong to more than two types The difference in depth of field. The method for adjusting the sensitivity of the digital camera according to claim 1, wherein the step of adjusting the current sensitivity of the camera module comprises: sequentially, according to the setting option of the sensitivity of the camera module, the current sensitivity. Increase the level by one. The method for adjusting the sensitivity of the digital camera according to claim 1, wherein the step of adjusting the current sensitivity of the camera module comprises: adjusting the sensitivity of the camera module to a current sensitivity of the camera. Times. The method for adjusting the sensitivity of the digital camera of claim 1, wherein the step of adjusting the current sensitivity of the camera module comprises: at least one of the deepest depths of the depths of the scenes to which the objects belong. The image information of the target object calculates an adjustment value of the sensitivity; and adjusts the current sensitivity of the camera module with the adjustment value. The method for adjusting the sensitivity of the digital camera according to claim 1, wherein the step of adjusting the current sensitivity of the camera module comprises: focusing on the camera module in the depth of field to which the target objects belong The image information of at least one of the objects of the depth of field other than the depth of field calculates an adjustment value of the sensitivity; and the current sensitivity of the camera module is adjusted by the adjustment value. The method for adjusting the sensitivity of the digital camera according to claim 1, further comprising: after adjusting the current sensitivity of the camera module, causing the flash to emit the pre-flash, and using the camera module to capture again The pre-flash image of the objects.