CN107437240B - Low-illumination image enhancement method for restraining highlight area - Google Patents
Low-illumination image enhancement method for restraining highlight area Download PDFInfo
- Publication number
- CN107437240B CN107437240B CN201710575380.5A CN201710575380A CN107437240B CN 107437240 B CN107437240 B CN 107437240B CN 201710575380 A CN201710575380 A CN 201710575380A CN 107437240 B CN107437240 B CN 107437240B
- Authority
- CN
- China
- Prior art keywords
- image
- highlight
- pixel
- low
- enhancement
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 238000000034 method Methods 0.000 title claims abstract description 40
- 238000005286 illumination Methods 0.000 title claims abstract description 24
- 230000000452 restraining effect Effects 0.000 title description 3
- 230000000694 effects Effects 0.000 claims abstract description 18
- 125000001475 halogen functional group Chemical group 0.000 claims abstract description 12
- 230000001629 suppression Effects 0.000 claims description 20
- 230000005540 biological transmission Effects 0.000 claims description 11
- 238000010586 diagram Methods 0.000 claims description 7
- 238000002834 transmittance Methods 0.000 claims description 6
- 230000005764 inhibitory process Effects 0.000 claims description 5
- 238000001914 filtration Methods 0.000 claims description 3
- 238000011084 recovery Methods 0.000 claims description 2
- 230000000007 visual effect Effects 0.000 abstract description 6
- 230000002401 inhibitory effect Effects 0.000 abstract 2
- 230000002708 enhancing effect Effects 0.000 abstract 1
- 238000003384 imaging method Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000012634 optical imaging Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T5/00—Image enhancement or restoration
- G06T5/73—Deblurring; Sharpening
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T5/00—Image enhancement or restoration
- G06T5/80—Geometric correction
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Theoretical Computer Science (AREA)
- Image Processing (AREA)
Abstract
The invention discloses a low-illumination image enhancement method for inhibiting a highlight area, which comprises the steps of firstly reversing a low-illumination image, introducing the concept of a bright channel to inhibit the highlight area, then enhancing the image according to an atmospheric scattering physical model by using a defogging method, and finally reversing the image again to obtain an enhancement effect image for inhibiting the highlight area. The method can adaptively process the low-illumination image, effectively inhibit the highlight area and eliminate the halo phenomenon at the same time, so that the enhanced image has more ideal contrast and visual effect, and the overall enhancement effect is greatly improved compared with the existing enhancement algorithm. The whole process can realize automation and self-energy without manual intervention.
Description
Technical Field
The invention relates to the field of image processing, in particular to a low-illumination image enhancement method for restraining a highlight area.
Background
With the rapid development of digital images and multimedia technologies, various types of optical imaging systems are increasing, and the requirements of people on the picture quality of the imaging systems are also increasing, such as various monitoring systems, target recognition and target tracking systems, because of the uncontrollable particularity of scenes, the picture quality is often difficult to meet the requirements, especially for images shot under weak illumination conditions such as night, the overall image quality is poor, the contrast is low, image details are seriously lost, the visibility is difficult to satisfy, inconvenience is brought to many works, and the application of the systems is limited to a great extent. The illumination environment of a night scene is complex, a highlight area often appears in an image, and most of the conventional image enhancement methods enhance the whole image without considering the influence of the highlight area on the enhanced image, so that the highlight area can generate diffusion and halo phenomena in the enhanced image.
The invention provides a low-illumination image enhancement method, which is characterized in that a high-brightness area is suppressed on the basis of a reversal image of a low-illumination image through a bright channel, the high-brightness area suppression image is recovered through a defogging method, and finally the image is reversed again to obtain an enhancement effect image of the high-brightness area suppression. Therefore, the enhancement effect image effectively inhibits the highlight area and effectively solves the halo phenomenon generated in the image enhancement process of the highlight area, and the enhancement effect image is more in line with the visual characteristics of human eyes.
Disclosure of Invention
The invention aims to provide a self-adaptive low-illumination image enhancement method which is easy to realize, has strong robustness and better accords with the visual characteristics of human eyes and inhibits a high-brightness area, thereby solving the problem of over-enhancement of the high-brightness area in the existing image enhancement method and effectively avoiding the halo phenomenon caused by a light source.
The purpose of the invention is realized by the following technical scheme: a low-illumination image enhancement method for suppressing a highlight region, the method comprising the steps of:
(1) inverting the low-illumination image L to obtain an inversion image R; luminance information R of color channel c at pixel (x, y) in reverse image Rc(x, y) is:
Rc(x,y)＝255-Lc(x,y) (1)
where c represents any of the three channels of image R, G, B, Lc(x, y) represents luminance information of a certain color channel at the pixel (x, y);
(2) carrying out highlight region suppression on the inverse image R in the step 1 by utilizing a bright channel principle, eliminating a halo effect and obtaining a highlight region suppression image Ib；
(3) Suppression of the highlighted areas in step 2 by defogging method fig. IbRestoring to obtain a restored image J;
(4) the obtained restoration image J is inverted again in accordance with the method of step 1, and the final enhancement image H with suppressed highlight areas is obtained.
Further, the step 2 specifically includes:
(2.1) carrying out highlight region suppression on the inverse map R in the step 1 by utilizing the principle of bright channel to obtain a transmission map t with suppressed highlight regionsbTransmittance of lightTransmission diagram tbGray value t at middle pixel (x, y)b(x, y) is:
wherein Ω is a local region where the pixel point p is located, (x)p,yp) Representing the coordinates, t, of a pixel point p0Is 0.1, AbIs the atmospheric natural light value of the bright area inhibition, beta is the [1.5,2 ]]。
(2.2) further modifying the resulting transmission map t with suppressed highlight region by guided filteringbObtaining a highlight region inhibition chart Ib。
The invention has the beneficial effects that: and inverting the image to form a pseudo fog image, performing highlight area suppression on the inverted image of the low-illumination image based on a bright channel, recovering the highlight area suppression image by using a defogging method, and finally inverting the image again to obtain an enhanced effect image of the highlight area suppression. Therefore, the enhancement effect image effectively inhibits the highlight area and effectively solves the halo phenomenon generated in the image enhancement process of the highlight area.
Drawings
FIG. 1 is a block flow diagram of the inventive method.
Fig. 2 is an arbitrary low illuminance image L.
Fig. 3 is an inversion diagram R obtained by inverting the low-illuminance image.
FIG. 4 is a high luminance region suppressed transmittance graph tb。
Fig. 5 is a diagram H of the final enhancement effect obtained by the method of the present invention.
Fig. 6 is a diagram of enhancement effect obtained by using a conventional enhancement algorithm.
Detailed Description
According to the method, firstly, the low-illumination image is reversed, the concept of a bright channel is introduced to suppress the high-brightness area, then the image is enhanced according to the atmospheric scattering physical model by using a defogging method, and finally the image is reversed again to obtain the enhancement effect image of the high-brightness area suppression. The method can adaptively process the low-illumination image, effectively inhibit the highlight area and eliminate the halo phenomenon at the same time, so that the enhanced image has more ideal contrast and visual effect, and the overall enhancement effect is greatly improved compared with the existing enhancement algorithm.
The suppression of highlight regions in the present invention is merely indicative of the enhancement effect of the present invention, and is not performed for a region of a specific luminance. According to the method, the highlight area in the low-illumination image can be automatically identified, and the suppression is realized.
The following detailed description is made with reference to the accompanying drawings and examples:
FIG. 1 is a simplified flow diagram of the method of the present invention. The present invention will be further described with reference to the following examples.
(1) Acquiring a low illumination image L, as shown in fig. 2;
(2) inverting the low-illumination image L to obtain an inversion image R;
Rc(x,y)＝255-Lc(x,y) (1)
where c represents any of the three channels of image R, G, B, Lc(x, y) represents luminance information of a certain color channel at the pixel (x, y), and the inversion graph R is shown in FIG. 3;
(3) the low illumination map by inversion can be regarded as a pseudo fog map, and in the fog map imaging model, the classical image degradation model is as follows:
Rc(x,y)＝Jc(x,y)t(x,y)+A(1-t(x,y)) (2)
Rc(x, y) and Jc(x, y) represent the degraded fog and haze-free plots, respectively, with A being the atmospheric weather value and t (x, y) being the atmospheric transmission plot. In the reverse image domain, the bright channel J of the image J is restoredbrightCan be represented by the following formula:
taking the maximum operation for equation (2) as follows:
wherein Ω is a local region where the pixel point p is located, and in this embodiment, the region is selected to be a rectangular region with p as the center and 9 pixels on side length, (x)p,yp) Representing the coordinates of a pixel p, AbThe atmospheric daylight value for bright area suppression is selected in this example as the 0.1% pixel value with the smallest median value in the bright channel. Combining equations (3) and (4) yields the following equation:
the bright channel principle is utilized to carry out highlight region suppression and halo effect elimination on the reverse image R, and the transmittance transmission image t with highlight region suppression is obtained through calculation according to the following formulabIn order to weaken only the highlight region and leave the other regions unaffected, a parameter β and an empirical constant t are introduced0Gray value tb(x, y) is:
in this example, the parameter β is 1.5, t0The obtained transmission map t with suppressed highlight regionbAs shown in fig. 4;
(4) further modifying the resulting transmission profile t with suppressed highlight region by guided filteringbObtaining a highlight region inhibition chart Ib；
(5) Suppression of highlight areas by defogging methodbRecovering, in this embodiment, a dark channel defogging method is selected to process the image to obtain a restored image J;
j is a recovery image to be recovered, A is an atmospheric natural light value, omega is a super-pixel homologous region where a pixel (x, y) is located, and t (x, y) is a dark channel atmospheric transmittance transmission image;
(6) the obtained restoration image J is inverted again in accordance with the method of step 1, and a final enhancement image with suppressed highlight areas is obtained, as shown in fig. 5.
According to the method, firstly, the low-illumination image is reversed, the concept of a bright channel is introduced to suppress the high-brightness area, then the image is enhanced according to the atmospheric scattering physical model by using a defogging method, and finally the image is reversed again to obtain the enhancement effect image of the high-brightness area suppression. It can be seen from fig. 6 that the image is enhanced by directly using the existing image enhancement algorithm, the highlight region has a very obvious over-enhancement phenomenon and even generates an obvious halo phenomenon, while it can be seen from fig. 5 that the method of the present invention can play a good effect of suppressing the highlight region and solve the halo problem, the details of the light center can be clearly seen, the original detail information of the image is retained, and the enhanced image more conforms to the visual effect of human eyes. The method can adaptively process the low-illumination image, effectively inhibit the highlight area and eliminate the halo phenomenon at the same time, so that the enhanced image has more ideal contrast and visual effect, and the overall enhancement effect is greatly improved compared with the existing enhancement algorithm.
Claims (1)
1. A low-illumination image enhancement method for suppressing a highlight region, comprising the steps of:
(1) inverting the low-illumination image L to obtain an inversion image R; luminance information R of color channel c at pixel (x, y) in reverse image Rc(x, y) is:
Rc(x,y)＝255-Lc(x,y) (1)
where c represents any of the three channels of image R, G, B, Lc(x, y) represents luminance information of a certain color channel at the pixel (x, y);
(2) carrying out highlight region suppression on the inverse image R in the step 1 by utilizing a bright channel principle, eliminating a halo effect and obtaining a highlight region suppression image Ib(ii) a The step (2) is specifically as follows:
(2.1) carrying out highlight region suppression on the inverse map R in the step 1 by utilizing the principle of bright channel to obtain a transmission map t with suppressed highlight regionsbTransmittance transmission diagram tbGray value t at middle pixel (x, y)b(x, y) is:
wherein Ω is a local region where the pixel point p is located, (x)p,yp) Representing the coordinates of pixel p, t0 being 0.1, AbIs the atmospheric natural light value of the bright area inhibition, beta is the [1.5,2 ]]；
(2.2) further modifying the resulting transmission map t with suppressed highlight region by guided filteringbObtaining a highlight region inhibition chart Ib；
(3) Suppressing the highlight area in step (2) by dark channel defogging method to obtain graph IbRestoring to obtain a restored image J;
j is a recovery image to be recovered, A is an atmospheric natural light value, omega is a super-pixel homologous region where a pixel (x, y) is located, and t (x, y) is a dark channel atmospheric transmittance transmission image;
(4) the obtained restored image J is inverted again in accordance with the method of step (1), and a final enhancement image H with suppressed highlight areas is obtained.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710575380.5A CN107437240B (en) | 2017-07-14 | 2017-07-14 | Low-illumination image enhancement method for restraining highlight area |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710575380.5A CN107437240B (en) | 2017-07-14 | 2017-07-14 | Low-illumination image enhancement method for restraining highlight area |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107437240A CN107437240A (en) | 2017-12-05 |
| CN107437240B true CN107437240B (en) | 2021-06-04 |
Family
ID=60461215
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710575380.5A Expired - Fee Related CN107437240B (en) | 2017-07-14 | 2017-07-14 | Low-illumination image enhancement method for restraining highlight area |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN107437240B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110163807B (en) * | 2019-03-20 | 2023-04-07 | 哈尔滨工业大学 | Low-illumination image enhancement method based on expected bright channel |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101783963A (en) * | 2010-02-10 | 2010-07-21 | 西安理工大学 | Nighttime image enhancing method with highlight inhibition |
| CN101902651A (en) * | 2009-05-28 | 2010-12-01 | 佳能株式会社 | Image processing equipment and image processing method |
| CN103020920A (en) * | 2013-01-10 | 2013-04-03 | 厦门大学 | Method for enhancing low-illumination images |
| CN104809700A (en) * | 2015-04-16 | 2015-07-29 | 北京工业大学 | Low-light video real-time enhancement method based on bright channel |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4997137B2 (en) * | 2008-02-20 | 2012-08-08 | オリンパス株式会社 | Solid-state imaging device |
| CA2655001C (en) * | 2009-02-20 | 2015-11-24 | Queen's University At Kingston | Marker localization using intensity-based registration of imaging modalities |
| US9881364B2 (en) * | 2015-08-10 | 2018-01-30 | Fuji Xerox Co., Ltd. | Image processing apparatus, image processing method and computer readable medium for image enhancement |
-
2017
- 2017-07-14 CN CN201710575380.5A patent/CN107437240B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101902651A (en) * | 2009-05-28 | 2010-12-01 | 佳能株式会社 | Image processing equipment and image processing method |
| CN101783963A (en) * | 2010-02-10 | 2010-07-21 | 西安理工大学 | Nighttime image enhancing method with highlight inhibition |
| CN103020920A (en) * | 2013-01-10 | 2013-04-03 | 厦门大学 | Method for enhancing low-illumination images |
| CN104809700A (en) * | 2015-04-16 | 2015-07-29 | 北京工业大学 | Low-light video real-time enhancement method based on bright channel |
Also Published As
| Publication number | Publication date |
|---|---|
| CN107437240A (en) | 2017-12-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107767354B (en) | Image defogging algorithm based on dark channel prior | |
| CN110148095B (en) | Underwater image enhancement method and enhancement device | |
| CN106251301B (en) | A kind of single image to the fog method based on dark primary priori | |
| CN106530257A (en) | Remote sensing image de-fogging method based on dark channel prior model | |
| CN108734670B (en) | Method for restoring single night weak-illumination haze image | |
| CN102750674B (en) | Video image defogging method based on self-adapting allowance | |
| CN107451966B (en) | Real-time video defogging method implemented by guiding filtering through gray level image | |
| WO2013018101A1 (en) | Method and system for removal of fog, mist or haze from images and videos | |
| Yuan et al. | A region-wised medium transmission based image dehazing method | |
| CN107360344B (en) | Rapid defogging method for monitoring video | |
| CN110689490A (en) | Underwater image restoration method based on texture color features and optimized transmittance | |
| CN109816608B (en) | Low-illumination image self-adaptive brightness enhancement method based on noise suppression | |
| CN107705258B (en) | Underwater image enhancement method based on three-primary-color combined pre-equalization and deblurring | |
| CN104253930A (en) | Real-time video defogging method | |
| CN107527325B (en) | Monocular underwater vision enhancement method based on dark channel priority | |
| KR102182697B1 (en) | Apparatus and method for processing image | |
| Gao et al. | Sandstorm image enhancement based on YUV space | |
| Kim et al. | Temporally x real-time video dehazing | |
| CN107977941B (en) | Image defogging method for color fidelity and contrast enhancement of bright area | |
| CN107437240B (en) | Low-illumination image enhancement method for restraining highlight area | |
| US8780235B2 (en) | Image processing method | |
| CN107203979B (en) | Low-illumination image enhancement method | |
| Wang et al. | A fast method of foggy image enhancement | |
| CN106709876A (en) | Optical remote sensing image defogging method based on the principle of dark pixel | |
| CN106296626B (en) | A kind of night video enhancement method based on gradient fusion |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20210604 |