CN114202484A - Image detail enhancement and its ASIC implementation method and system - Google Patents
Image detail enhancement and its ASIC implementation method and system Download PDFInfo
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Abstract
The invention relates to the technical field of image processing, in particular to an image detail enhancement and ASIC implementation method and system, which comprises the following steps: s1 initialization, inputting the image to be processed, and carrying out parameter-configurable weighted mean filtering on the input image; s2, calculating the difference between the current central pixel point and the average filtering output, and looking up a table to obtain a difference gain coefficient and a gray scale gain coefficient; and S3, combining the weighted average filtering output in S1 and the difference output and the two gain coefficients in S2, and calculating a detail enhancement output result. The method can adjust the detail gain according to the pixel value of the current pixel point, and effectively solves the problems of overshoot and undershoot in the image detail enhancement; different filter coefficients can be selected according to different application scenes, different gain curves are selected according to different application scenes, and detail enhancement is only carried out on a Y channel in a YUV domain, so that the calculation amount is effectively reduced, and ASIC implementation is facilitated.
Description
Technical Field
The invention relates to the technical field of image processing, in particular to an image detail enhancement method and an ASIC implementation method and system.
Background
The images are affected by the imaging environment, the imaging equipment and the transmission system in the process of acquisition and transmission, so that the finally received images contain noise, detail information is difficult to identify, and the accuracy of subsequent image processing is greatly hindered. The purpose of image detail enhancement is to improve the image quality, purposefully enhance the recognizable capability of certain target information according to the subsequent image processing requirement, express the interested target characteristic information in the image more finely, and inhibit noise.
The prior art cannot adjust the detail gain according to the current pixel value; the problems of "overshoot" and "low overshoot" cannot be solved; different filter coefficients cannot be selected according to different application scenes; the calculation amount is too large to be beneficial to ASIC realization. Thus, provided herein is an image detail enhancement and ASIC implementation method and system thereof.
Disclosure of Invention
Aiming at the defects of the prior art, the invention discloses an image detail enhancement method and an ASIC implementation method and system thereof, which are used for solving the problem that the prior art can not adjust the detail gain according to the current pixel value; the problems of "overshoot" and "low overshoot" cannot be solved; different filter coefficients cannot be selected according to different application scenes; the calculated amount is too large, which is not beneficial to the realization of ASIC.
The invention is realized by the following technical scheme:
in a first aspect, the present invention provides an image detail enhancement method and an ASIC implementation method thereof, including the following steps:
s1 initialization, inputting the image to be processed, and carrying out parameter-configurable weighted mean filtering on the input image;
s2, calculating the difference between the current central pixel point and the average filtering output, and looking up a table to obtain a difference gain coefficient and a gray scale gain coefficient;
and S3, combining the weighted average filtering output in S1 and the difference output and the two gain coefficients in S2, and calculating a detail enhancement output result.
Furthermore, in the method, when the average filtering is weighted, the average filtering coefficient obtains different filtering coefficients according to different positions of the pixel points in the filtering window, and meanwhile, the filtering coefficients are adjusted in real time according to different application scenes.
Furthermore, in the method, when the weighted average filtering is performed, the filter coefficients are all integer multiples of 2, and the multiplication is replaced by a shifting mode in the ASIC implementation.
Further, in the method, the calculation procedure of the weighted mean filtering is as follows:
M=WSUM∑PJWJ
WSUM=1/∑WJ
wherein, XJFor the shift value, W, of each pixel point within the filtering windowJIs the filter coefficient for each pixel within the filter window.
Further, in the method, the flow of calculating the filtering difference value is as follows:
LDIFF=P-M
wherein, P is the central pixel point in the filtering window.
Furthermore, the method uses unsharp masking, and the enhancement of the high frequency information is achieved by first high-pass filtering and multiplying by a scaling factor, and then adding the result to the original image.
Furthermore, in the method, the difference gain coefficient FD and the gray gain coefficient FI are obtained by looking up a table, and the detail enhancement output is as follows:
Y=Y+LDIFF*FI*FD。
in a second aspect, the present invention provides an image detail enhancement and ASIC implementation system for implementing the image detail enhancement and ASIC implementation method of the first aspect, comprising an image caching module, a data selector, a gray scale gain coefficient look-up table module, a configurable weighted mean filtering module, a difference gain coefficient look-up table module, and an output calculation module.
Furthermore, the image caching module is configured to cache image data, and generate a 7x7 neighborhood of the current pixel point;
the data selector is used for selecting the central pixel point participating in the detail enhancement and the neighborhood pixel point data thereof;
the gray gain coefficient lookup module is used for looking up a table according to the Y channel value of the current pixel point to obtain a gray gain coefficient;
the configurable weighted mean filtering module is used for calculating to obtain a filtered pixel value and a difference value between an original image and a filtered image;
the difference gain coefficient table look-up module is used for looking up a table to obtain a difference gain coefficient according to the image difference obtained by the configurable weighted mean filter;
and the output calculation is used for calculating to obtain an output image according to the Y channel value of the central pixel, the image difference value, the gray gain coefficient and the difference gain coefficient.
Furthermore, the table entry of the gray scale gain coefficient look-up table module can be configured by a CPU or other main controllers;
the filter coefficient of the configurable weighted mean filtering module can be configured by a CPU or other main controllers;
the table entry of the difference gain coefficient table look-up module can be configured by a CPU or other main controller.
The invention has the beneficial effects that:
the method can adjust the detail gain according to the pixel value of the current pixel point, and effectively solves the problems of overshoot and undershoot in the image detail enhancement; the invention can select different filter coefficients according to different application scenes, select different gain curves according to different application scenes, and only perform detail enhancement on a Y channel in a YUV domain, thereby effectively reducing the calculation amount and being beneficial to the realization of an ASIC.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a diagram of the image detail enhancement and its ASIC implementation of the present invention;
FIG. 2 is a table look-up of the delta gain factor according to an embodiment of the present invention;
FIG. 3 is a table-look-up of gray scale gain factors according to an embodiment of the present invention;
FIG. 4 is a system diagram of image detail enhancement and ASIC implementation thereof, in accordance with an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
Referring to fig. 1, the present embodiment provides an image detail enhancement method and an ASIC implementation method thereof, including the following steps:
s1 initialization, inputting the image to be processed, and carrying out parameter-configurable weighted mean filtering on the input image;
s2, calculating the difference between the current central pixel point and the average filtering output, and looking up a table to obtain a difference gain coefficient and a gray scale gain coefficient;
and S3, combining the weighted average filtering output in S1 and the difference output and the two gain coefficients in S2, and calculating a detail enhancement output result.
The embodiment can adjust the detail gain according to the pixel value of the current pixel point; the problems of 'overshoot' and 'undershoot' in the image detail enhancement can be effectively solved.
According to the embodiment, different filter coefficients can be selected according to different application scenes; different gain curves can be selected according to different application scenarios.
The embodiment only performs detail enhancement on the Y channel in the YUV domain, thereby effectively reducing the calculation amount and being beneficial to ASIC realization.
Example 2
In a specific implementation level, this embodiment provides a weighted mean filtering and a filtering difference calculation, in this embodiment, the image detail enhancement usually performs detail enhancement on RGB components in an RGB domain, respectively, and this detail enhancement method can achieve a better effect, but has a large calculation amount and is easy to distort colors.
Therefore, the embodiment performs detail enhancement in the YUV domain and performs enhancement only in the Y channel, which can effectively reduce the amount of calculation without causing color distortion.
| W0 | W1 | W2 | W3 | W2 | W1 | W0 |
| W1 | W4 | W5 | W6 | W5 | W4 | W1 |
| W2 | W5 | W7 | W8 | W7 | W5 | W2 |
| W3 | W6 | W8 | W9 | W8 | W6 | W3 |
| W2 | W5 | W7 | W8 | W7 | W5 | W2 |
| W1 | W4 | W5 | W6 | W5 | W4 | W1 |
| W0 | W1 | W2 | W3 | W2 | W1 | W0 |
In this scheme, as the window size of the above-mentioned mean filtering is 7x7, the coefficient of each pixel point in the window is as shown in the above table, and the calculation flow of the weighted mean filtering is:
M=WSUM∑PJWJ
WSUM=1/∑WJ
the calculation process of the filtering difference value comprises the following steps:
LDIFF=P-M
wherein, XJFor the shift value, W, of each pixel point within the filtering windowJThe filter coefficient of each pixel in the filter window is shown, and P is a central pixel point in the filter window.
In this embodiment, the same filter coefficient is used for all the pixels in the filter window in consideration of the conventional mean filtering, and the filter coefficient is fixed, so that different filter coefficients cannot be obtained by optimization according to different application scenarios.
Therefore, the average filter coefficient of the embodiment obtains different filter coefficients according to different positions of the pixel points in the filter window, and the filter coefficients can be different according to the different positions. The filtering coefficient is adjusted in real time by applying the scene, and the aluminum rod performance of the system is improved.
Since the filter coefficients of the present embodiment are all integer multiples of 2, the multiplication can be replaced by a shifting manner in ASIC implementation, thereby further reducing the calculation amount.
Example 3
In a specific implementation level, the embodiment provides a gain coefficient table lookup and detail enhancement output, and a classic algorithm of image enhancement in the embodiment is an UNsharp Masking (UNsharp Masking) technique.
In the embodiment, high-frequency information can be enhanced by high-pass filtering and multiplying by a scaling coefficient, and adding the result to the original image.
Although the present embodiment is simple to implement and can be applied to most application scenarios, the output image will have significant "overshoot" or "low-overshoot" artifacts. In order to eliminate "overshoot" or "low-shoot" artifacts, the "overshoot" or "low-shoot" artifacts must be properly controlled.
In this embodiment, a table is respectively looked up according to the calculated filtering difference and the pixel value of the current pixel point, so as to obtain a filtering gain coefficient and a gray gain coefficient. The strength of detail enhancement is controlled by two gain coefficients, so that the problem of overshoot or low overshoot can be effectively solved.
The difference gain coefficient lookup table of this embodiment is shown in fig. 2, and the gray gain coefficient lookup table is shown in fig. 3, and according to the two curves, the difference gain coefficient FD and the gray gain coefficient FI can be obtained by lookup.
As can be seen from fig. 2 and 3, when the difference value and the gray value are too large or too small, both gain coefficients are constant and small, so that the problem of "overshoot" or "undershoot" can be effectively solved. Meanwhile, in the [0,1] area, along with the increase of the difference value and the gray value, the gain coefficient is increased, the image details can be effectively enhanced, and in the [1,3] area, along with the increase of the difference value and the gray value, the gain coefficient is gradually reduced, so that the overshoot is prevented.
Finally, the output of the detail enhancement is:
Y=Y+LDIFF*FI*FD。
example 4
Referring to fig. 4, the embodiment provides an image detail enhancement and ASIC implementation system thereof, which includes an image buffer module, a data selector, a gray gain coefficient look-up table module, a configurable weighted average filtering module, a difference gain coefficient look-up table module, and an output calculation module.
The image caching module of the embodiment is used for caching image data and generating a 7x7 neighborhood of a current pixel point;
the data selector is used for selecting a central pixel point participating in detail enhancement and neighborhood pixel point data thereof;
the gray scale gain coefficient lookup module is used for looking up a table according to the Y channel value of the current pixel point to obtain a gray scale gain coefficient;
the configurable weighted mean filtering module is configured to calculate a filtered pixel value and a difference value between an original image and a filtered image;
the difference gain coefficient lookup module is used for looking up a table to obtain a difference gain coefficient according to the image difference obtained by the configurable weighted mean filter;
and the output calculation is used for calculating to obtain an output image according to the Y channel value of the central pixel, the image difference value, the gray gain coefficient and the difference gain coefficient.
The table entry of the gray scale gain coefficient table look-up module of the embodiment can be configured by a CPU or other main controllers;
the filter coefficient of the weighted average filtering module configured in the embodiment can be configured by a CPU or other main controller;
the table entry of the difference gain coefficient table look-up module of this embodiment can be configured by the CPU or other main controller.
In conclusion, the method can adjust the detail gain according to the pixel value of the current pixel point, and effectively solves the problems of overshoot and undershoot in the image detail enhancement; the invention can select different filter coefficients according to different application scenes, select different gain curves according to different application scenes, and only perform detail enhancement on a Y channel in a YUV domain, thereby effectively reducing the calculation amount and being beneficial to the realization of an ASIC.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
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| TW200731767A (en) * | 2006-02-15 | 2007-08-16 | Actvision Technologies Inc | Device and method for image edge enhancement |
| CN102651122A (en) * | 2011-02-24 | 2012-08-29 | 索尼公司 | Image enhancement apparatus and method |
| CN104157003A (en) * | 2014-07-18 | 2014-11-19 | 北京理工大学 | Heat image detail enhancement method based on normal distribution adjustment |
| CN110796626A (en) * | 2019-11-13 | 2020-02-14 | 中国电子科技集团公司信息科学研究院 | Image sharpening method and device |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TW200731767A (en) * | 2006-02-15 | 2007-08-16 | Actvision Technologies Inc | Device and method for image edge enhancement |
| CN102651122A (en) * | 2011-02-24 | 2012-08-29 | 索尼公司 | Image enhancement apparatus and method |
| CN104157003A (en) * | 2014-07-18 | 2014-11-19 | 北京理工大学 | Heat image detail enhancement method based on normal distribution adjustment |
| CN110796626A (en) * | 2019-11-13 | 2020-02-14 | 中国电子科技集团公司信息科学研究院 | Image sharpening method and device |
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