CN110620878A - On-chip area exposure imaging method - Google Patents
On-chip area exposure imaging method Download PDFInfo
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- CN110620878A CN110620878A CN201910929396.0A CN201910929396A CN110620878A CN 110620878 A CN110620878 A CN 110620878A CN 201910929396 A CN201910929396 A CN 201910929396A CN 110620878 A CN110620878 A CN 110620878A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/70—Circuitry for compensating brightness variation in the scene
- H04N23/73—Circuitry for compensating brightness variation in the scene by influencing the exposure time
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/70—Circuitry for compensating brightness variation in the scene
- H04N23/741—Circuitry for compensating brightness variation in the scene by increasing the dynamic range of the image compared to the dynamic range of the electronic image sensors
Abstract
The invention provides an on-chip area exposure imaging method, which adopts an implementation mode that a pixel array of an image sensor is divided into a plurality of areas by 64 lines, each area is provided with a group of exposure time, the areas are provided with a plurality of groups of different exposure times, and the areas are respectively exposed and output each pixel value. The time points at which the exposure of the plurality of regions is started are different, and the time points at which the exposure is ended are the same. The pixel value output by the pixel array is the original pixel value, or the exposure time of a certain area is set as the unit exposure time, and the pixel values of other areas are output values which are linearly calculated according to the proportion of the current exposure time to the unit exposure time. The on-chip area exposure imaging method provided by the invention can set different exposure time according to scene areas in application, and can realize the improvement of the dynamic range of the acquired image. Compared with the implementation scheme in the prior art, the method and the device can effectively reduce the problem of motion blur.
Description
Technical Field
The invention relates to an image processing technology of an image sensor, in particular to an on-chip area exposure imaging method of the image sensor, which is used for improving the dynamic range of an image output by the image sensor.
Background
Image sensors are widely used in video surveillance and other related fields. In some traffic monitoring camera shooting application occasions, the brightness of a traffic signal lamp after being started is equivalent to the surrounding environment, and the brightness is brighter. When the image sensor is used for video monitoring shooting of scenes containing traffic lights, the red lights with weak illumination are prone to color cast (except red, other color channels are over-exploded) in cloudy days, and the problem of traffic light over-exposure can occur in shooting at night. The reason for this problem is mainly that the current image sensor design is generally linear, and the linear image sensor has a small illumination range and cannot collect all signals when the low-illumination environment changes to the strong-light environment. Therefore, the output dynamic range of the light-emitting diode cannot simultaneously satisfy the brightness range of the traffic light and the surrounding environment. To solve the above problem, it is necessary to improve the dynamic range of the image output from the image sensor to meet the application requirements of different scenes.
The dynamic range of the output of the image sensor is increased by adopting a mode of outputting two frames of images for synthesis so as to increase the dynamic range. In the specific design, two frames of images have different exposure times, one frame of image has a long exposure time, and the other frame of image has a short exposure time. One frame of image with a long exposure time can obtain image details clearly in a low-illumination scene, and another frame of image with a short exposure time can obtain image details in a high-illumination scene. The two frames of images are combined, so that a clear image with details of both the low-illumination scene and the high-illumination scene can be obtained. However, in the implementation of the two-frame synthesis, the first frame image needs to be read and stored, and the second frame image needs to be read and then merged. Therefore, in a specific application, the two-frame image synthesis has a problem of motion blur.
Based on the above problems, the present invention provides an innovative on-chip area exposure imaging method to effectively solve the problem of dynamic range output by an image sensor in multiple application environments.
Disclosure of Invention
The invention aims to provide an on-chip area exposure imaging method of an image sensor, which comprises the following specific implementation methods:
dividing a pixel array of an image sensor into a plurality of regions in units of 64 lines;
each area is provided with a group of exposure time, and a plurality of areas are provided with a plurality of groups of different exposure time;
respectively exposing the plurality of areas, and outputting each pixel value by the pixel array after exposure is finished;
the pixel value output by the pixel array is a pixel original value, or the exposure time of a certain area is set as unit exposure time, and the pixel values of other areas are output values which are linearly calculated according to the proportion of the current exposure time to the unit exposure time;
the linear calculation formula of the pixel values of the other regions is Po ═ Pi × (E0/Ex), where E0 is the set unit exposure time, Ex is the current exposure time of the other regions, and Pi is the current pixel values of the other regions;
setting the exposure time of a certain area as unit exposure time, preferably, selecting the exposure time of the certain area with the longest exposure time as the unit exposure time;
the exposure time of each row of pixels in the pixel array is the same;
the exposure time of partial areas in the plurality of areas is the same or different; a plurality of areas with the same exposure time can be set as exposure combination, so that the setting can reduce the setting times of exposure parameters;
the time points of the exposure start of part of the areas in the plurality of areas are different, the time points of the exposure end are the same, and the exposure time lengths are different;
the maximum exposure time ratio of different areas in the plurality of areas is 16:1, the output effect is influenced by the fact that the exposure ratio is too large and the signal-to-noise ratio is reduced;
when each pixel value output by the pixel array is a pixel original value, the maximum bit width of the pixel array is 12 bits; when a plurality of regions output by the pixel array of the image sensor output pixel values after linear calculation according to the exposure time proportion, the bit width is 16 bits at most; and when the output value of the pixel value output by the pixel array after the linear calculation exceeds the maximum bit width of 16 bits, outputting the pixel value with the maximum bit width of 16 bits.
The proposal provided by the invention adopts the imaging method of local exposure and adopts different exposure time for different areas in the process of exposing one frame of image of the image sensor, thus effectively improving the dynamic range of the output image and solving various problems in image output under the condition of inconsistent scene brightness in application. Meanwhile, compared with the scheme adopted in the prior art, the implementation scheme for improving the output dynamic range can effectively reduce the problem of motion blur and meet the application requirement.
Drawings
FIG. 1 is a schematic diagram of different areas divided by a pixel array of an image sensor; and
FIG. 2 is a basic flowchart of the on-chip area exposure imaging method according to the present invention.
Detailed Description
The invention scheme provided by the invention is explained in detail by combining the figure 1, the figure 2 and the application example. The drawings are provided for purposes of illustration and description, and are not to be construed as limiting the invention to the specific aspects and concepts herein disclosed.
Fig. 1 is a schematic diagram of different area divisions of a pixel array of an image sensor. As shown in fig. 1, the pixel array of the image sensor is divided into a plurality of regions in units of 64 lines, and a region structure diagram including regions 1 to 8 is listed in the example of fig. 1. In the figure, for the purpose of schematically illustrating the region division, a partial region division of the pixel array is illustrated as a schematic diagram including only 8 regions. It will be understood by those skilled in the art that in practical design applications, the image sensor includes a pixel array formed by pixel units with several rows and columns, and can be divided into application embodiments including several areas. Region 1 identified in fig. 1 contains 64 rows, with the same pixel cell exposure time setting for each row to save design resources. The areas 1 to 3 may be set to the same exposure time, constituting a first exposure combination; the areas 4 to 8 can be set to the same exposure time to form a second exposure combination; the first exposure combination and the second exposure combination may be respectively set to different exposure times. In the present application, only two sets of exposure combinations are illustrated, and in a specific application, a plurality of exposure combinations can be set according to the exposure time. Different areas with the same exposure time are set as exposure combination, so that the times of setting exposure parameters can be reduced, and the setting time for updating is shortened. Since the exposure time of the areas 1 to 3 and the areas 4 to 8 are different, the time points of starting exposure of the areas 1 to 3 and the areas 4 to 8 are different, but the time points of ending exposure are consistent, so that the reading and control processing of each pixel unit in the pixel array after the exposure is ended is facilitated.
Fig. 2 is a basic flow of the on-chip area exposure imaging method provided by the present invention, and the following describes in detail an application embodiment scheme of the present invention with reference to the area division example shown in fig. 1:
first, a pixel array of an image sensor is divided into a plurality of regions in units of 64 lines:
in a specific application embodiment, the pixel array may be divided into several regions, and each region includes 64 rows of pixel units. For example, a 2Mp image sensor, the pixel array may comprise 1920H 1080V pixels, H being a row and V being a column. It can be divided to contain 30 regions, each containing 64 rows.
Setting a group of exposure time for each area, and setting a plurality of groups of exposure time for a plurality of areas:
the exposure time of each line in each area is set to be the same, so that the resource design is saved; when a plurality of sets of exposure times are set for a plurality of areas, a part of the areas may be set to the same exposure time, and different areas having the same exposure time may be set to exposure combinations, for example, areas 1 to 3 in fig. 1, which are exposure combinations having the same exposure time. Setting the areas having the same exposure time as the exposure combination can reduce the number of times of setting of the exposure parameters in the design to shorten the time required for updating the settings.
And respectively exposing the plurality of areas, wherein after exposure is finished, the pixel array outputs each pixel value:
since the plurality of regions have a plurality of different sets of exposure times, the time point at which each region starts exposure is set differently, and the time point at which exposure ends is set consistently. This arrangement is advantageous for the reading operation after the exposure is finished.
The pixel value output by the pixel array may be an original value output by the pixel, or may be an output value obtained by setting the exposure time of a certain area as the unit exposure time, for example, the exposure time of the area 1 as the unit exposure time, and the pixel values of other areas are linearly calculated according to the ratio of the current exposure time to the unit exposure time. In general, the exposure time of the selected region having the longest exposure time is set as the unit exposure time. The formula Po of the linear calculation is Pi (E0/Ex), where E0 is the set unit exposure time, Ex is the current exposure time of other regions, and Pi is the current pixel value of other regions.
The exposure time ratio set between different regions is 16:1 at the maximum, and since an excessive exposure time ratio causes a problem of signal to noise ratio (SNR) and the output effect is deteriorated, the maximum ratio is set to 16: 1.
The pixel array output of the image sensor may be the original value of the pixel, which may be up to 12 bits wide. When the output of the pixel array is set according to the exposure time proportion and the pixel value after linear calculation is output, the maximum bit width is 12 bits +4 bits and 16 bits. And if the maximum bit width of the pixel values after linear calculation exceeds the maximum value of 16 bits, outputting the pixel values according to the maximum value of 16 bits.
The scheme of the application embodiment provided by the invention can realize that the image sensor exposes in a frame of image by adopting different exposure time lengths in the subarea, and improve the output dynamic range, thereby meeting the application environment of bright and dark multi-scene. Compared with the prior art, the imaging method of the image sensor provided by the invention can effectively reduce the problem of motion blur in the implementation scheme of the prior art.
The various embodiments of the invention and the accompanying drawings are presented for illustrative purposes and various equivalent modifications are possible in different forms without departing from the broader spirit and scope of the invention. Modifications of the embodiments of the invention which are based on the above detailed description are considered to fall within the scope of the invention. The terms used in the following claims should not be construed to be limited to the specific embodiments disclosed in the specification and the claims. Rather, the full scope of the claims is to be construed according to the established doctrines of claim interpretation. The specification and drawings are to be regarded in an illustrative rather than a restrictive sense.
Claims (10)
1. An on-chip area exposure imaging method, comprising:
a pixel array of the image sensor is divided into a plurality of regions in units of 64 lines;
each area is provided with a group of exposure time, and the plurality of areas are provided with a plurality of groups of different exposure time;
exposing the plurality of areas respectively, and outputting each pixel value by the pixel array after exposure is finished;
wherein, the pixel value output by the pixel array is the pixel original value; or setting the exposure time of a certain area as the unit exposure time, and the pixel values of other areas as output values which are calculated linearly according to the proportion of the current exposure time to the unit exposure time.
2. The on-chip area exposure imaging method according to claim 1, wherein the linear calculation formula of the pixel values of the other areas is Po-Pi (E0/Ex), where E0 is the set unit exposure time, Ex is the current exposure time of the other areas, and Pi is the current pixel value of the other areas.
3. The on-chip area exposure imaging method according to claim 1, wherein when the exposure time of a certain area is set as a unit exposure time, the exposure time of an area with a longer exposure time is selected as the unit exposure time.
4. The on-chip area exposure imaging method according to claim 1, wherein the exposure time of each row of pixels in the pixel array is the same.
5. The on-chip area exposure imaging method according to claim 1, wherein a plurality of sets of exposure times in the plurality of areas are set to be partially the same or different.
6. The on-chip area exposure imaging method according to claim 5, wherein areas with the same exposure time are set as exposure combinations.
7. The on-chip area exposure imaging method according to claim 1, wherein the time points at which exposure of the plurality of areas starts are different, and the time points at which exposure ends are the same.
8. The on-chip area exposure imaging method according to claim 1, wherein the exposure time ratio set for different areas of the plurality of areas is 16:1 or less.
9. The on-chip area exposure imaging method according to claim 8, wherein when the pixel value output by the pixel array is the pixel original value, the bit width is less than or equal to 12 bits; and when the pixel values are output after the plurality of areas of the pixel array are linearly calculated according to the exposure time proportion, the bit width of the pixel array is less than or equal to 16 bits.
10. The on-chip area exposure imaging method according to claim 9, wherein when an output value bit width of a pixel value output by the pixel array after linear calculation is larger than 16 bits, a pixel value with a bit width of 16 bits is output.
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| CN111175774A (en) * | 2020-01-14 | 2020-05-19 | 炬佑智能科技(苏州)有限公司 | Control method of TOF sensor module |
| CN113225494A (en) * | 2021-04-29 | 2021-08-06 | 深圳市阿达视高新技术有限公司 | Progressive exposure image generation method, system, image processing apparatus, and medium |
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| WO2021195896A1 (en) * | 2020-03-30 | 2021-10-07 | 华为技术有限公司 | Target recognition method and device |
| CN114972127A (en) * | 2022-07-29 | 2022-08-30 | 武汉精立电子技术有限公司 | Moire pattern elimination method, device, equipment and readable storage medium |
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Address after: 201203 room 612, 6 floor, 3 building, 111 Cheung Road, Pudong New Area, Shanghai. Applicant after: Starway (Shanghai) Electronic Technology Co.,Ltd. Address before: 201203 room 612, 6 floor, 3 building, 111 Cheung Road, Pudong New Area, Shanghai. Applicant before: Siteway (Shanghai) Electronic Technology Co.,Ltd. |
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Application publication date: 20191227 |