CN104717430B - Image processing method and image processing apparatus - Google Patents

Abstract

An image processing device includes a camera unit, a control unit, an image processing unit and a storage unit. The camera unit obtains a first image. The control unit adjusts the exposure value of the camera unit to control the average brightness value of the dark part of the first image and the contrast value of the first image. The image processing unit is coupled to the camera unit and the storage unit, and generates a second image based on the first image and a first algorithm stored in the storage unit, and generates a third image based on the first image and a second algorithm stored in the storage unit. The image processing unit generates a fourth image based on the brightness value of the first image, the brightness value of the second image, the brightness value of the third image and a weight array. The present invention can avoid the problem of occupying memory space caused by shooting multiple images with different exposure values, and avoid the problem of incomplete output images due to inconsistent contents of multiple images, and at the same time achieve real-time generation of quasi-high dynamic range images.

Description

Image processing method and image processing device

technical field

The present invention relates to an image processing method and an image processing device, in particular to an image processing method and an image processing device for obtaining pseudo-high dynamics in real time.

Background technique

In recent years, photography has become one of the important interests of modern man. Whether it is the built-in camera of a laptop computer, a tablet computer or a mobile phone, people's desire to take pictures of beautiful things anytime, anywhere is getting higher and higher. However, not every moment of the environment is suitable for taking pictures. When the surrounding light is insufficient, the backlight or the ambient brightness is high-contrast (parts of the environment with extremely high brightness and extremely low brightness at the same time), the captured image will be limited by the hardware of the camera itself, and cannot present the original original appearance.

In the prior art, high dynamic range imaging (High dynamic range; HDR) is a technology used to achieve a larger exposure dynamic range than ordinary digital image technology. It shoots through a variety of different exposure values and produces multiple images. images, and then fuse the images with different exposure values to output an optimized image. However, in addition to taking up more storage space, multiple images require multiple exposure values for high dynamic range imaging, which will reduce the speed of image processing. In addition, the method adopted by high dynamic range imaging is to shoot the same location at different times with different exposure values. If the camera is not equipped with a tripod or other fixed devices, it is very easy to have inconsistencies in the content of multiple images, resulting in afterimages or incomplete images in the fusion output image.

Contents of the invention

The invention provides an image processing method used in an image processing device. The image processing device includes a camera unit, a control unit, an image processing unit and a storage unit. The image processing method includes the following steps: obtaining a first image through the camera unit, wherein the control unit adjusts the exposure value of the camera unit to control the average brightness value of the dark part of the first image and the contrast value of the first image; the image processing unit according to the first The image and a first algorithm stored in the storage unit generate a second image; the image processing unit generates a third image according to the first image and a second algorithm stored in the storage unit; and the image processing unit generates a third image according to the first image The luminance value of , the luminance value of the second image, the luminance value of the third image and a weight array generate a fourth image.

The invention also provides an image processing device, which includes a camera unit, a control unit, an image processing unit and a storage unit. The camera unit acquires a first image. The control unit is coupled with the camera unit, and adjusts the exposure value of the camera unit to control the average brightness value of the dark part of the first image and the contrast value of the first image. The storage unit is coupled to the control unit. The image processing unit is coupled with the camera unit, and generates a second image according to the first image and a first algorithm stored in the storage unit, and generates a first image according to the first image and a second algorithm stored in the storage unit Three images. The image processing unit generates a fourth image according to the brightness value of the first image, the brightness value of the second image, the brightness value of the third image and a weight array.

Therefore, the present invention can avoid the problem of taking up memory space caused by shooting multiple images with different exposure values, and avoid the problem of incomplete output images due to inconsistent content of multiple images, and simultaneously achieve real-time generation of virtual images. High Dynamic Range Imagery.

Description of drawings

FIG. 1 is a schematic diagram of the appearance of an image processing device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of an internal structure of an image processing device according to an embodiment of the present invention.

FIG. 3 is a flowchart of an image processing method according to an embodiment of the present invention.

detailed description

An image processing method and an image processing device according to preferred embodiments of the present invention will be described below with reference to related drawings, wherein the same elements will be described with the same reference symbols.

FIG. 1 is a schematic diagram of the appearance of an image processing device according to an embodiment of the present invention. Referring to FIG. 1 , in this embodiment, the image processing device 11 is a tablet computer equipped with a camera unit 111 . However, the present invention is not limited thereto. In other implementations, the image processing device can also be a notebook computer, a smart phone, a multimedia audio-visual device, a portable video game device or other portable electronic devices equipped with a camera lens. In addition, the image processing device can also be an electronic device or system in the form of a stationary installation of a surveillance system for surveillance or a security camera system.

Please refer to FIG. 2 , which is a schematic diagram of an internal structure of an image processing device according to an embodiment of the present invention. The image processing device 21 includes a camera unit 211 , a control unit 212 , an image processing unit 213 and a storage unit 214 . The camera unit 211 acquires a first image according to a user's operation. The control unit 212 is coupled to the camera unit 211 and adjusts the exposure value of the camera unit 211 to control the average brightness value of the dark part of the first image and the contrast value of the first image.

In detail, the control unit 212 controls the exposure value of the camera unit 211 so that the average brightness value of the dark portion of the first image captured by the camera unit 211 is between 30 and 40, and the contrast value of the first image is between 30 and 40. Between 80% and 90% of the built-in contrast value of unit 211. Wherein, the first image generated through the above parameters will be beneficial to subsequent image processing.

The image processing unit 213 is coupled to the camera unit 211 , and the storage unit 214 is coupled to the control unit 212 and the image processing unit 213 . The image processing unit 213 generates a second image according to the first image obtained by the camera unit 211 and a first algorithm stored in the storage unit 214, and generates a second image according to the first image and a second algorithm stored in the storage unit 214 a third image. In addition, the image processing unit 213 generates a fourth image according to the luminance value of the first image, the luminance value of the second image, the luminance value of the third image and a weight array. In this embodiment, the image processing unit 213 increases the brightness of each pixel of the first image according to the first algorithm stored in the storage unit 214 to generate the second image, and the image processing unit 213 generates the second image according to the algorithm stored in the storage unit 214 The second algorithm increases the contrast of the first image, in particular the contrast of the region pixels, to generate the third image.

In this embodiment, the control unit 212 and the image processing unit 213 are described as two separate components, but in other implementations, the control unit 212 and the image processing unit 213 may be based on the circuit layout and integrated into a single component by design.

In addition, in this embodiment, the weight array is a default weight array stored in the storage unit 214 . Wherein, the weight array can be a set of values stored in the storage unit 214, for example: [1/3, 1/3, 1/3]. It should be noted that the number of weight arrays stored in the storage unit 214 can store one set of weight arrays or multiple sets of weight arrays according to product requirements and image processing design. When multiple sets of weight arrays are stored in the storage unit 214 , the image processing unit 213 can select different weight arrays according to different photographing modes. For example, the image processing device 21 can further have a user operation interface 215, which can provide multiple shooting modes for the user to choose, such as: night mode, fireworks mode, outdoor daylight mode or outdoor artificial light mode, etc. Moreover, the storage unit 214 has different weight arrays corresponding to the aforementioned different shooting modes. When the user selects one of the shooting modes, the image processing unit 213 will select the corresponding weight array from the storage unit 214 . In addition, the image processing device 21 may further include a sensing unit (not shown in the figure), which can sense the conditions of the external environment, such as the brightness of the foreground and the brightness of the background, and provide the sensed results to the image processing unit 213 , so that the image processing unit 213 selects a set of weight arrays by itself according to the sensing result. In addition, in other implementations, the weight array can also be an externally input weight array, that is, the user can input the desired weight array through the user operation interface 215, so that the user can Adjust the effect of the video according to your needs and preferences.

Next, please refer to the flow chart of FIG. 3 together with FIG. 2 to describe the image processing method of the preferred embodiment of the present invention, which can be applied to the above-mentioned image processing device 21 . The steps of the image processing method include steps S01 to S04. Step S01 obtains a first image through the camera unit 211 , wherein the control unit 212 adjusts the exposure value of the camera unit 211 to control the average brightness value of the dark part of the first image and the contrast value of the first image.

In detail, the control unit 212 controls the exposure value of the camera unit 211 so that the average brightness value of the dark part of the first image is between 30 and 40, and the contrast value of the first image is between the built-in contrast of the camera unit 211. between 80% and 90% of the value. In this embodiment, the camera parameters of the camera unit 211 are controlled through the control unit 212 to generate a first image that is beneficial to subsequent image processing.

In step S02 , the image processing unit 213 generates a second image according to the first image and the first algorithm stored in the storage unit 214 . In this embodiment, when the camera unit 211 acquires a better first image, it will be temporarily stored in the storage unit 214 . At the same time, the image processing unit 213 will process the first image through the first algorithm. Wherein, the image processing unit 213 will increase the brightness of each pixel of the first image according to the first algorithm to generate the second image. In practice, the image processing unit 213 can adjust in different proportions according to the original brightness value of each pixel of the first image, for example, when the original brightness value of the pixel is equal to or less than a default value, the first function (function) is performed. ) operation, a higher brightness adjustment ratio is given, and when the original brightness of the pixel is greater than the default value, the second function operation is used to give a lower brightness adjustment ratio. In addition, the aforementioned first algorithm may also use the same operation function for the original brightness of each pixel of the first image, so as to increase the brightness of each pixel. In this embodiment, the first algorithm may be, for example, a wide dynamic range (WDR) algorithm, and the second image generated by the image processing unit 213 may be temporarily stored in the storage unit 214 .

In step S03 , the image processing unit 213 generates a third image according to the first image and a second algorithm stored in the storage unit 214 . In this embodiment, the image processing unit 213 will use the second algorithm to process the first image to increase the contrast of the first image, especially to increase (enhance) the contrast of the region of the first image, and generate the third image . Wherein, the image processing unit 213 can analyze the brightness of the foreground and the brightness of the background of the first image, and adjust the ratio of the brightness of the foreground to the brightness of the background, and the second algorithm can be, for example, local histogram equalization (Contrast-Limited Adaptive Histogram Equalization; CLAHE ) algorithm, and the third image generated by the image processing unit 213 can be temporarily stored in the storage unit 214 . At this time, data such as the first image, the second image, and the third image will be stored in the storage unit 214 .

In step S04 , the image processing unit 213 generates a fourth image according to the luminance value of the first image, the luminance value of the second image, the luminance value of the third image and a weight array. In this embodiment, the image processing unit 213 extracts the first image, the second image and the third image from the storage unit 214, and according to the weight array stored in the storage unit 214, the brightness of the first image, the second image The brightness of the image and the brightness of the third image are weighted to obtain a fourth image after mixing the three. For example, when the weight array stored in the storage unit 214 is [1/3, 1/3, 1/3], and it is assumed that the brightness value of the first image is 40, the brightness value of the second image is 100 and The luminance value of the third image is 80, and the luminance value of the fourth image is 70 (40×1/3+100×1/3+80×1/3=70) after being calculated by the aforementioned weight array. However, the numerical values and calculation methods described above are calculated for the pixels (Pixels) corresponding to the first image, the second image, and the third image. After all the pixels in each image are calculated with the above weights, the fourth image can be generated, and the fourth image is the pseudo high dynamic range image processed by the image processing method described in this embodiment. In addition, the fourth image can be output to a display unit (not shown) through the image processing unit 213 for viewing or confirmation by the user. In other implementations, the weight array can be an externally input weight array, that is, the user can input the desired weight array through the user operation interface 215 .

In addition, the fourth image generated after the weight calculation can be adjusted in other details, such as softening, sharpening or other image processing to make the final output image more perfect and output to the display unit. However, the above-mentioned further image adjustment or parameter adjustment may have different additional processing according to the actual use situation, which is not limited in the present invention.

It should be added that, among the above steps, there is no restriction on the order of implementation of step S02 and step S03 . In other words, step S02 may be performed before step S03, or step S03 may be performed prior to step S02, or step S02 and step S03 may be performed simultaneously. In order to speed up the speed of image processing, in this embodiment, it is taken as an example that step S02 and step S03 are performed simultaneously.

In summary, according to an image processing method and an image processing device of the present invention, a first image is obtained through the camera unit, and the control unit adjusts the exposure value of the camera unit to control the average brightness value of the dark part of the first image. and the contrast value of the first image, so the image processing method and the image processing method of the present invention only need to take one original image, and the original image has better processing conditions, so it can avoid taking multiple images with different exposure values , resulting in the problem of occupying memory space, and avoiding the problem of incomplete output images due to inconsistencies in the content of multiple images, and at the same time achieving real-time generation of pseudo-high dynamic range images.

Although the present invention has been disclosed as above with the embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be defined by the claims.

Claims (8)

1. A kind of image processing method, is used for image processing device, and above-mentioned image processing device comprises camera unit, control unit, image processing unit and storage unit, and above-mentioned image processing method comprises the following steps: The first image is obtained by the camera unit, wherein the control unit adjusts the exposure value of the camera unit to control the average brightness value of the dark part of the first image and the contrast value of the first image; The image processing unit increases the brightness of each pixel of the first image according to the first image and the first algorithm stored in the storage unit to generate a second image; The image processing unit increases the regional contrast of the first image according to the first image and the second algorithm stored in the storage unit to generate a third image; and The image processing unit generates a fourth image according to the brightness value of the first image, the brightness value of the second image, the brightness value of the third image and the weight array. 2. The image processing method according to claim 1, wherein the control unit adjusts the exposure value of the camera unit, so that the average brightness value of the dark part of the first image is between 30 and 40, and the The contrast value is between 80% and 90% of the built-in contrast value of the aforementioned camera unit. 3. The image processing method according to claim 1, wherein the weight array is a default weight array stored in the storage unit. 4. The image processing method according to claim 1, wherein said weight array is an externally input weight array. 5. The image processing method according to claim 1, further comprising the steps of: Softening processing is performed on the above fourth image. 6. The image processing method according to claim 1, further comprising the steps of: Perform sharpening processing on the above fourth image. 7. An image processing device, comprising: The camera unit obtains the first image; a control unit, coupled to the camera unit, and adjust the exposure value of the camera unit to control the average brightness value of the dark part of the first image and the contrast value of the first image; a storage unit coupled to the control unit; and an image processing unit, coupled to the above-mentioned camera unit and the above-mentioned storage unit, and adjusts the brightness of each pixel of the above-mentioned first image according to the above-mentioned first image and the first algorithm stored in the above-mentioned storage unit to generate a second image, and increasing the regional contrast of the first image according to the first image and the second algorithm stored in the storage unit to generate a third image; The image processing unit generates a fourth image according to the luminance value of the first image, the luminance value of the second image, the luminance value of the third image and the weight array. 8. The image processing device according to claim 7, wherein the control unit adjusts the exposure value of the camera unit so that the average brightness value of the dark part of the first image is between 30 and 40, and the The contrast value is between 80% and 90% of the built-in contrast value of the aforementioned camera unit.