CN101179662A - Image dark corner correction method and device - Google Patents

Abstract

The invention provides an image dark corner correction method, which is executed in an image acquisition device and comprises a lens and a photosensitive assembly. A first image is formed on the photosensitive assembly through the lens. And capturing the part of the first image in the imaging area of the photosensitive assembly as a second image. Determining whether the second image has a dark corner by comparing the brightness corresponding to a first area and the brightness corresponding to a second area on the second image, wherein the first area does not include the edge of the second image, and the second area includes the edge of the second image. If the second image has a dark corner, the imaging area of the photosensitive assembly is adjusted.

Description

Image vignetting correction method and device

technical field

The present invention relates to image capture technology, and in particular to a method for correcting image vignetting and an image capture device using the method.

Background technique

When the angle of view of the lens of the digital camera does not match the photosensitive component, the photosensitive range of the photosensitive component will be smaller than the effective imaging range, or the light energy at the edge of the digital camera lens will attenuate too much, and the surrounding area of the image will be obviously darkened, affecting Image quality, known as vignette or lens shading. For example, in FIG. 1 , the imaging area of the lens 11 on the photosensitive element 10 is the area A2, which is the light-sensing range of the photosensitive element 10, and the effective imaging range which does not completely cover the photosensitive element, that is, the area A1. This will cause the brightness of the four corners of the image captured by the photosensitive element 10 to be dark. Figure 2 shows an example of an image with lens occlusion. For relatively mild lens shading phenomenon, image processing method can be used to compensate its brightness. However, for the relatively serious lens shading phenomenon, especially when the corners of the photosensitive components are covered, it can no longer be solved by simple image processing.

The lens shading phenomenon of some digital cameras does not exist all the time. Moreover, when the lens shading phenomenon occurs, the camera system will not pre-interpret it, so it cannot correctly distinguish whether the lens shading occurs.

Contents of the invention

In view of this, the object of the present invention is to provide a method for correcting image vignetting and an image capture device using the method.

Based on the above purpose, the present invention provides a method for correcting image vignetting, the method for correcting image vignetting is implemented in an image capture device, the image capture device includes a lens and a photosensitive component, including: A first image is formed on the above-mentioned photosensitive element; the part of the above-mentioned first image within the imaging area of the above-mentioned photosensitive element is captured as a second image; by comparing the brightness corresponding to a first area on the above-mentioned second image with a second The brightness corresponding to the area is used to determine whether the second image has vignetting, wherein the first area does not include the edge of the second image, and the second area includes the edge of the second image; and if the second image has dark corners Angle, then adjust the above-mentioned imaging area of the above-mentioned photosensitive assembly.

In the image vignetting correction method of the present invention, the second region is a corner of the second image.

In the method for correcting vignetting according to the present invention, the adjusted imaging region does not contain the portion of the second region that has been determined to be vignetting.

The image vignetting correction method of the present invention further includes: generating the brightness corresponding to the second region according to the average brightness of the pixels in the second region.

The image vignetting correction method of the present invention further includes: generating the brightness corresponding to the second region according to the brightness corresponding to a third region, a fourth region and a fifth region of the second image.

In the method for correcting vignetting according to the present invention, the adjusted imaging region does not contain the portions determined to be vignetting in the second, third, fourth and fifth regions.

In the image vignetting correction method according to the present invention, the luminances corresponding to a third area, a fourth area and a fifth area of the second image are respectively the average luminance values of pixels in each area.

The image vignetting correction method according to the present invention further includes: capturing a third image through the adjusted imaging area; and when the third image captured through the adjusted imaging area still has vignetting , continue to adjust the above-mentioned imaging area of the above-mentioned photosensitive assembly.

In the image vignetting correction method of the present invention, the purpose of adjusting the imaging area is achieved by shrinking the imaging area.

In the image vignetting correction method of the present invention, the purpose of adjusting the imaging area is achieved by shifting the imaging area.

In addition, the present invention further provides an image capture device, comprising: a photosensitive component, which forms a first image on the photosensitive component through a lens; and a processor, which captures the first image on the photosensitive component The part inside the imaging area is used as a second image. By comparing the brightness corresponding to a first area on the second image with the brightness corresponding to a second area, it is determined whether the second image has vignetting, wherein the first area does not The edge of the second image is included, and the second area includes the edge of the second image, and if the second image has vignetting, the processor adjusts the imaging area of the photosensitive element.

In the image capture device of the present invention, wherein the second area includes a corner of the second image.

In the image capture device according to the present invention, the adjusted imaging area does not contain the portion of the second area that has been determined to be a vignetting.

In the image capture device of the present invention, the processor generates the brightness corresponding to the second region according to the average brightness of the pixels in the second region.

In the image capture device according to the present invention, the processor generates the brightness corresponding to the second region according to the brightness corresponding to a third region, a fourth region and a fifth region of the second image.

In the image capture device according to the present invention, the adjusted imaging area does not contain the part determined as vignetting in the second, third, fourth or fifth area.

In the image capture device according to the present invention, the luminances corresponding to a third area, a fourth area and a fifth area of the second image are respectively the average luminance values of pixels in each area.

In the image capture device of the present invention, wherein the processor captures a third image through the adjusted imaging area, and when the third image captured through the adjusted imaging area still has When vignetting occurs, the processor continues to adjust the imaging area of the photosensitive component.

The image capturing device of the present invention further includes: a display, wherein, when the third image has no vignetting, the processor outputs the third image to the display.

In the image capturing device of the present invention, the purpose of adjusting the imaging area is achieved by shrinking the imaging area.

In the image capture device of the present invention, the purpose of adjusting the imaging area is achieved by shifting the imaging area.

Description of drawings

Figure 1: A schematic diagram of the imaging area and photosensitive area of a photosensitive component;

Figure 2: Schematic illustration of an example of an image that typically has vignetting;

Fig. 3: shows the structural block diagram of an embodiment of an image capture device;

Figure 4a: shows a schematic diagram of a photosensitive element; and

Figure 4b: shows the imaging area of the photosensitive assembly of Figure 4a;

Figure 5: a flow chart showing an embodiment of an image vignetting correction method;

Figure 6: A schematic diagram showing the above-mentioned photosensitive assembly and its reconfigured imaging area;

Figure 7: Shows an example of the image in Figure 2 after removing vignetting.

Detailed ways

The following descriptions are of preferred embodiments of the invention. Its purpose is to illustrate the general principles of the invention. It should be understood that the configurations of the following entities and steps are just examples and can be adjusted, and should not be regarded as limitations of the present invention. The scope of the present invention shall be defined by the scope of the patent application.

A method for correcting image vignetting and an image capture device using the method are disclosed below. It should be understood that the configurations of the following entities and steps are just examples and can be adjusted.

In the image capture device 100 shown in FIG. 3 , the processor 1 is coupled to the memory 2 , the photosensitive element 4 , the display 5 and the control unit 9 . The processor 1 is a digital signal processor (Digital Signal Processor, DSP for short). The control unit 9 is used to control the operation of each component of the image capture device 100 , and can be integrated into the processor 1 .

The photosensitive element 4 may be an array composed of photosensitive elements made of complementary metal-oxide semiconductor (Complementary Metal-Oxide Semiconductor, CMOS for short) or Charge-Coupled Device (CCD for short). The photosensitive element 4 receives light beams from the lens 8 to generate electronic signals as image data. The range where the light beam passes through the lens 8 and is projected on the photosensitive element 4 is referred to as the photosensitive range hereinafter. The lens 8 can be implemented by various lenses. For example, the lens 8 may be composed of several lenses, and the focusing device 91 may include mechanical components for driving the position of the focusing lens or the position of the photosensitive component 4 therein.

The control unit 9 is coupled to the focusing device 91 for driving the focusing device 91 to adjust the focal length of the lens 8 or the position of the photosensitive element 4 . In addition, only a part of the photosensitive element 4 is an imaging area. Referring to FIG. 4a, the processor 1 may initially use the area A3 as the imaging area. The processor 1 removes the image data pixels generated by the photosensitive elements outside the above-mentioned imaging area, processes only the image data pixels generated by the photosensitive elements in the above-mentioned imaging area, and then displays them on the display 5 or stores them in the memory 2 or other storage devices.

The control unit 9 activates auto-focus and image capture according to the state of the input device 6 . The input device 6 may include a shutter release button on the image capture device 100 or an external control device.

Referring to FIG. 3 and FIG. 5 , the image capture device 100 implements an image vignetting correction method.

A first image is formed on the photosensitive element 4 through the lens 8 (step S2). The processor 1 captures the portion of the first image within the imaging area (area A3 ) of the photosensitive element 4 as the second image 41 (step S4 ). Since the area A3 includes all photosensitive elements of the photosensitive element 4 , the current second image 41 is substantially the same as the above-mentioned first image. The processor 1 can store the second image 41 in the memory 2 to perform the following processing steps.

The processor 1 calculates brightness corresponding to the center and corners of the second image 41 (step S6 ).

For example, referring to FIG. 4 b , the processor 1 calculates brightness corresponding to the regions A40 , A50 , A60 , A70 and A80 on the second image 41 . The area A40 covers the center of the second image 41 , and the areas A50 , A60 , A70 and A80 cover the four corners of the second image 41 . Although the areas A40 , A50 , A60 , A70 , and A80 are shown in FIG. 4 b as an example, they are not limited thereto. For example, the area A40 can be an area substantially located at the center of the second image 41, and the areas A50, A60, A70, A80 can be four areas adjacent to the edge of the second image 41, and each area can be each kind of shape. The areas A40 , A50 , A60 , A70 , and A80 can be determined according to a specific ratio of the size of the second image 41 . For example, the second image 41 can be divided into 16 grids, and each of the above-mentioned regions is located in one of the grids.

The processor 1 may generate brightness corresponding to each of the above regions according to the average brightness of the pixels in each of the above regions. However, the luminance corresponding to each of the above regions may also be obtained by using other algorithms. The processor 1 then calculates the corresponding brightness representing the four corners of the second image 41 according to the corresponding brightness of the areas A50 , A60 , A70 , A80 corresponding to the four corners.

The processor 1 determines whether there is a vignetting in the second image 41 by comparing the brightness corresponding to the center of the second image 41 with the brightness corresponding to the four corners (step S8 ).

If the second image 41 has vignetting, the processor 1 adjusts the aforementioned imaging area of the photosensitive element 4 (step S10 ). The processor 1 can reduce the aforementioned imaging area of the photosensitive element 4 to exclude the portion of the photosensitive element 4 that produces vignetting. For example, the areas A4, A5, A6, A7 and A8 on the photosensitive element 4 in FIG. 4a correspond to the areas A40, A50, A60, A70 and A80 on the second image 41 in FIG. 4b respectively. That is, the areas A4 , A5 , A6 , A7 and A8 on the photosensitive element 4 respectively generate pixels in the areas A40 , A50 , A60 , A70 and A80 of the second image 41 . The reduced imaging area can exclude the areas A4, A5, A6, A7, and A8 in the photosensitive assembly 4, such as the area A31 in FIG. 6 . It should be understood that the processor 1 can also only compare the brightness corresponding to the center of the second image 41 and one corner to determine whether the second image has vignetting, and adjust the imaging area relatively so that the adjusted imaging area does not include the corner. Therefore, the processor 1 does not necessarily reduce the imaging area when there is a vignetting, and may only translate the imaging area to avoid the vignetting.

The processor 1 captures a third image through the reduced imaging area (ie, the area A31 ) (step S4 ), and repeats the above processing steps in FIG. 5 to determine whether the third image has vignetting. When the third image captured by the reduced imaging area still has vignetting, continue to adjust the imaging area of the photosensitive element 4 and repeat the above processing steps. When the image captured by the photosensitive element 4 has no vignetting, the processor 1 outputs the image to the display 5 (step S12 ). Figure 7 shows an example of the image in Figure 2 after removing vignetting. The processor 1 can capture and store the image to a storage device after removing the vignetting.

Therefore, the method of the present invention can detect whether the vignetting occurs in the image capture device, and eliminate the vignetting by resetting the imaging area of the photosensitive element, without installing additional devices to detect the vignetting. This method is also applicable when vignetting cannot be eliminated by color compensation.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention.

Claims (21)

1. a video dark corner correcting method is undertaken by an image capture unit, and above-mentioned image capture unit comprises a camera lens and a photosensory assembly, it is characterized in that, described video dark corner correcting method comprises:

See through above-mentioned camera lens and on above-mentioned photosensory assembly, form one first image;

Capture above-mentioned first image at the imaging region of above-mentioned photosensory assembly with interior part as one second image;

Via the brightness of the brightness of a first area correspondence on more above-mentioned second image and a second area correspondence to determine whether above-mentioned second image has dark angle, wherein above-mentioned first area does not comprise the edge of above-mentioned second image, and above-mentioned second area comprises the edge of above-mentioned second image; And

If above-mentioned second image has dark angle, then adjust the above-mentioned imaging region of above-mentioned photosensory assembly.

2. video dark corner correcting method as claimed in claim 1 is characterized in that, above-mentioned second area is an angle of above-mentioned second image.

3. video dark corner correcting method as claimed in claim 2 is characterized in that adjusted above-mentioned imaging region does not contain the part of the above-mentioned second area that has been judged to be dark angle.

4. video dark corner correcting method as claimed in claim 2 is characterized in that, described video dark corner correcting method further comprises:

According to the average brightness of the pixel in the above-mentioned second area to produce the brightness of above-mentioned second area correspondence.

5. video dark corner correcting method as claimed in claim 4 is characterized in that, described video dark corner correcting method further comprises:

According to the corresponding brightness in one the 3rd zone of above-mentioned second image, one the 4th zone and one the 5th zone to produce the brightness of above-mentioned second area correspondence.

6. video dark corner correcting method as claimed in claim 5 is characterized in that, adjusted above-mentioned imaging region do not contain above-mentioned second, third, be judged to be the part at dark angle in the 4th and the 5th zone.

7. video dark corner correcting method as claimed in claim 5 is characterized in that, one the 3rd zone of above-mentioned second image, one the 4th zone and the corresponding brightness in one the 5th zone are respectively the average brightness of the pixel in each zone wherein.

8. video dark corner correcting method as claimed in claim 1 is characterized in that, described video dark corner correcting method further comprises:

Via adjusted above-mentioned imaging region to capture one the 3rd image; And

When still dark angle being arranged, continue to adjust the above-mentioned imaging region of above-mentioned photosensory assembly via above-mentioned the 3rd image that adjusted above-mentioned imaging region captured.

9. video dark corner correcting method as claimed in claim 1 is characterized in that, reaches the purpose of adjusting above-mentioned imaging region to dwindle above-mentioned imaging region.

10. video dark corner correcting method as claimed in claim 1 is characterized in that, reaches the purpose of adjusting above-mentioned imaging region with the above-mentioned imaging region of translation.

11. an image capture unit is characterized in that, described image capture unit comprises:

One photosensory assembly sees through a camera lens and form one first image on above-mentioned photosensory assembly; And

One processor, capture above-mentioned first image at the imaging region of above-mentioned photosensory assembly with interior part as one second image, via the brightness of the brightness of a first area correspondence on more above-mentioned second image and a second area correspondence to determine whether above-mentioned second image has dark angle, wherein above-mentioned first area does not comprise the edge of above-mentioned second image, and above-mentioned second area comprises the edge of above-mentioned second image, and, if above-mentioned second image has dark angle, then above-mentioned processor is adjusted the above-mentioned imaging region of above-mentioned photosensory assembly.

12. image capture unit as claimed in claim 11 is characterized in that, above-mentioned second area comprises an angle of above-mentioned second image.

13. image capture unit as claimed in claim 12 is characterized in that, adjusted above-mentioned imaging region does not contain the part of the above-mentioned second area that has been judged to be dark angle.

14. image capture unit as claimed in claim 12 is characterized in that, above-mentioned processor according to the average brightness of the pixel in the above-mentioned second area to produce the brightness of above-mentioned second area correspondence.

15. image capture unit as claimed in claim 14 is characterized in that, above-mentioned processor according to the corresponding brightness in one the 3rd zone of above-mentioned second image, one the 4th zone and one the 5th zone to produce the brightness of above-mentioned second area correspondence.

16. image capture unit as claimed in claim 15 is characterized in that, adjusted above-mentioned imaging region do not contain above-mentioned second, third, be judged to be the part at dark angle in the 4th or the 5th zone.

17. image capture unit as claimed in claim 15 is characterized in that, one the 3rd zone of above-mentioned second image, one the 4th zone and the corresponding brightness in one the 5th zone are respectively the average brightness of the pixel in each zone wherein.

18. image capture unit as claimed in claim 11, it is characterized in that, above-mentioned processor via adjusted above-mentioned imaging region to capture one the 3rd image, and, when still dark angle being arranged via above-mentioned the 3rd image that adjusted above-mentioned imaging region captured, above-mentioned processor continues to adjust the above-mentioned imaging region of above-mentioned photosensory assembly.

19. image capture unit as claimed in claim 18 is characterized in that, described image capture unit further comprises:

One display, wherein, when above-mentioned the 3rd image did not have dark angle, above-mentioned processor exported above-mentioned the 3rd image to aforementioned display device.

20. image capture unit as claimed in claim 11 is characterized in that, reaches the purpose of adjusting above-mentioned imaging region to dwindle above-mentioned imaging region.

21. image capture unit as claimed in claim 11 is characterized in that, reaches the purpose of adjusting above-mentioned imaging region with the above-mentioned imaging region of translation.

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