CN107578404B - View-based access control model notable feature is extracted complete with reference to objective evaluation method for quality of stereo images - Google Patents

View-based access control model notable feature is extracted complete with reference to objective evaluation method for quality of stereo images Download PDF

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CN107578404B
CN107578404B CN201710721546.XA CN201710721546A CN107578404B CN 107578404 B CN107578404 B CN 107578404B CN 201710721546 A CN201710721546 A CN 201710721546A CN 107578404 B CN107578404 B CN 107578404B
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丁勇
孙光明
胡拓
孙阳阳
周一博
邓瑞喆
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Zhejiang University ZJU
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Abstract

Complete the invention discloses a kind of extraction of view-based access control model notable feature refers to objective evaluation method for quality of stereo images.The left and right view of stereo pairs is handled to obtain corresponding disparity map;Image co-registration is carried out to the left and right view of stereo pairs respectively and obtains middle reference and distorted image, Saliency maps are referred to and are distorted using spectrum residual error vision significance model, and logical integration obtains vision significance figure, visual information feature is extracted from middle reference and distorted image and depth information feature is extracted from the disparity map of stereo pairs, carry out similarity measurement, obtain the Measure Indexes for each visual information feature that vision significantly increases, it is supported vector machine training prediction, obtain objective quality scores, realize the mapping to stereo image quality, complete the measurement and evaluation of stereo image quality.Picture quality proposed by the invention, which is objectively evaluated, has good consistency with subjective assessment, and performance is better than existing stereo image quality evaluation method.

Description

View-based access control model notable feature is extracted complete with reference to objective evaluation method for quality of stereo images
Technical field
The full reference extracted the invention belongs to technical field of image processing more particularly to a kind of view-based access control model notable feature is vertical Body method for objectively evaluating image quality.
Background technique
Various distortions always occur in image sampling, transmission, compression and reconstruction processes for image, and the mankind are to figure As the quality of information also require it is higher and higher, so stereo image quality assessment technique exists with the development of 3D video and technology It is become more and more important in human society life.It is every since subjective stereo image quality evaluation method requires human viewer A image is offered to subjective mass fraction.The defects of these methods are time consuming nature and weak projectivity, it is quite necessary to development visitor The stereo image quality evaluation method of sight, with realize it is automatic, efficiently, objectively evaluate stereo image quality.Ideal objective IQA Index should have the ability of good forecast image quality, and completely the same with subjective measurement.
Stereo image quality, which objectively evaluates, can be divided into three classifications: entirely with reference to method, half with reference to method and without reference side Method.The main distinction of these three types of methods is different to the degree of dependence of original reference image.And it is ground due to now both domestic and external Study carefully hot spot to be concentrated mainly on full reference and evaluate measure without reference stereo image quality, wherein about full reference picture quality The research of evaluation is more, and technology is comparatively more mature, and the model established on this basis and subjective measurement consistency are higher. But since stereo-picture vision mode system is still not perfect, three-dimensional image objective quality evaluation is still the heat studied now Point and difficult point.
Summary of the invention
Complete the invention discloses a kind of extraction of vision notable feature refers to objective evaluation method for quality of stereo images.Its mesh Be to assist to extract stereo-picture visual signature, and comprehensive visual characteristic information is to realize opposition using vision significance model The measurement and evaluation of stereo image quality are completed in the mapping of body picture quality.
The technical solution adopted by the present invention is that:
Firstly, the left and right view for referring to and being distorted stereo pairs is handled respectively using structural similarity algorithm, Obtain corresponding disparity map;The left and right view for referring to and being distorted stereo pairs is carried out respectively using binocular view blending algorithm Image co-registration obtains middle reference and distorted image.Secondly, utilizing spectrum residual error vision significance to middle reference and distorted image Model is referred to and is distorted Saliency maps, and integrates vision significance figure by maximizing formula.Then, from middle reference and Distorted image extracts visual information feature and extracts depth information feature from disparity map, and in the guidance of vision significance figure Lower progress similarity measurement is assisted, the Measure Indexes of each visual information feature are obtained.Finally, referring to each visual information characteristic measure Mark is supported vector machine training prediction, realizes mapping to stereo image quality, completes the measurement of stereo image quality and comments Valence.
The technical solution adopted by the present invention to solve the technical problems is as follows:
Step (1) input is with reference to stereo pairs and distortion stereo pairs, wherein each stereo pairs respectively include Left view and right view image;
Step (2) constructs Log Gabor filter model, carries out at convolution algorithm to the stereo pairs in step (1) Reason respectively obtains reference and is distorted the energy response figure of stereo image pair or so view;
The expression formula of Log Gabor filter is as follows:
Wherein, f0And θ0It is centre frequency and the azimuth of Log Gabor filter, σθAnd σfRespectively represent filter Azimuth bandwidth and radial bandwidth, f and θ respectively represent radial coordinate and the azimuth of filter.
By Log Gabor filter and after referring to and being distorted stereo image pair or so view progress convolution, obtain corresponding Energy response figure, expression formula is as follows:
Wherein, I (x, y) is the left view or right view of reference and distortion stereo pairs,For convolution algorithm;
Step (3) extracts disparity map with distortion stereo pairs to the reference stereo pairs that step (1) inputs respectively;
The right view for the stereo pairs that step (4) inputs step (1) is according to the disparity map obtained in step (3) The level that parallax value carries out pixel moves to right, the calibration right view I that construction and left view pixel coordinate pair are answeredR((x+d), y), so Left view is obtained based on step (2) afterwards and calibrates the energy response figure of right view, calculates normalized left view weight map WL(x, Y) and calibration right view weight map WR((x+d), y), expression is as follows:
Wherein, FL(x, y) and FR((x+d), y) is respectively the energy sound of the left view that step (2) obtains and calibration right view The parallax value of respective coordinates in the disparity map D that Ying Tu, d are calculated for step (3);
The ginseng that the left view and step (4) of reference and distortion stereo pairs that step (5) is based in step (1) obtain Examine and be distorted stereo pairs calibration right view and normalized left view weight map and calibration right view weight map, utilize Binocular view Fusion Model is realized to the image co-registration of stereo-picture, and reference and distortion intermediate image is respectively obtained;Binocular The formula of view fusion is as follows:
CI (x, y)=WL(x,y)×IL(x,y)+WR((x+d),y)×IR((x+d),y) (5-1)
Wherein, CI (x, y) is the fused intermediate image of binocular view, IL(x, y) and IR((x+d), y) is respectively vertical The left view and calibration right view of body image pair;
The middle reference and distorted image that step (6) obtains step (5) extract reference and distortion vision significance respectively Figure, and it is integrated, the vision significance figure S after establishing integrationf
The disparity map of reference stereo pairs and distortion stereo pairs that step (7) is obtained using step (3) extracts deep Characteristic information is spent, and measurement is made to the distortion level of the disparity map of distortion stereo pairs;Using the method for pixel domain error The similitude for extracting the depth characteristic information of reference and distortion stereo pairs, as reaction distortion stereo pairs in disparity map It improves quality the index of distortion level, expression formula is as follows:
Wherein, DrefRepresent the disparity map of reference picture, DdisThe disparity map of distorted image is represented, E () is mean function, ε For the constant greater than zero, preventing denominator is zero, Index1And Index2It is two similarity measurements figureofmerits of depth characteristic information;
The middle reference and distorted image that step (8) obtains step (5) extract edge and textural characteristics respectively;
Process of convolution is carried out by Prewitt operator and by altimetric image, obtains the gradient map comprising edge contour information, is utilized The expression formula of the marginal information feature of Prewitt operator extraction middle reference and distorted image is as follows:
Wherein, f (x, y) is the left/right view of stereo pairs,For convolution algorithm, hxAnd hyIt is 3 × 3 Prewitt Vertical formwork and horizontal shuttering are respectively intended to the horizontal edge and vertical edge of detection image.Template expression formula is as follows:
The extraction of texture information feature uses local binary patterns LBP, and the expression formula of LBP is as follows:
Wherein, gcIt is the gray value of the central pixel point of image, gpIt is the gray value of the neighbor pixel of image, x and y generation The coordinate value of table central pixel point.Sgn (x) is jump function.
The visual information feature and step (6) for the middle reference and distorted image that step (9) extracts step (8) are established The multiplication put pixel-by-pixel of vision significance figure, obtain the visual information feature of vision significance enhancing, expression It is as follows:
GMSR(x, y)=GMR(x,y)*Sf(x,y) GMSD(x, y)=GMD(x,y)*Sf(x,y) (9-1)
TISR(x, y)=TIR(x,y)*Sf(x,y) TISD(x, y)=TID(x,y)*Sf(x,y) (9-2)
ISR(x, y)=IR(x,y)*Sf(x,y) ISD(x, y)=ID(x,y)*Sf(x,y) (9-3)
Wherein, GMR、TIRAnd IRIt is the edge, texture and brightness information of middle reference image, GM respectivelyD、TIDAnd ID It is the edge, texture and brightness information of intermediate distorted image respectively;SfVision after the integration obtained for step (6) is significant Property figure;
Step (10) carries out similarity measurement, expression to the visual information feature for the conspicuousness enhancing extracted in step (9) Formula is as follows:
Wherein, GMSR、TISRAnd ISRIndicate that edge, texture and the luminance information of the conspicuousness enhancing of middle reference image are special Sign, GMSD、TISDAnd ISDIndicate edge, texture and the luminance information of the conspicuousness enhancing of intermediate distorted image, Index3、Index4 And Index5Respectively represent the similarity measurements figureofmerit at edge, texture and luminance information feature, C4It is a constant greater than zero, It is zero the purpose is to prevent denominator;
The middle reference and distorted image that step (11) obtains step (5) carry out down-sampled processing, obtain L scale Middle reference and distorted image, under L scale space middle reference and the same applying step of distorted image (6), (9) and (10) method carries out the foundation of vision significance figure, the extraction of visual signature and similarity measurement, and N number of similitude is always obtained Measure Indexes, then N=2L+2;
Down-sampled method is as follows: input piece image obtains filtering image by low-pass filter, then schemes to filtering As carry out decimation factor be m down-sampled processing, obtain it is down-sampled after image.
Each Measure Indexes obtained in step (12) integration step (8) and (11) are supported vector machine SVR training Prediction obtains optimum prediction model, and is mapped as the objective assessment score of picture quality.
Wherein, what the view-based access control model notable feature according to patent was extracted is complete with reference to the stereo image quality side of objectively evaluating Method, it is characterised in that the step (3) includes the following steps:
Step (3.1) will be referred to respectively and the right view all pixels point level of distortion stereo image pair moves to right k times, The step-length moved every time is s pixel, the k width amendment right view I after obtaining horizontal move to rightR((x+i*s), y), (i=1,2 ... K), each width amendment right view is corresponding marked as i, and (i=1,2 ... k);
Step (3.2) calculates separately the left view of stereo image pair using structural similarity algorithm SSIM and k width is corrected The structural similarity of right view obtains k width structural similarity figure.SSIM algorithm expression formula is as follows:
Wherein, μxAnd μyRespectively indicate a corresponding image in the left view and amendment right view image of stereo pairs Mean value in block;σxAnd σyRespectively indicate a corresponding image block in the left view and amendment right view image of stereo pairs Interior variance yields;σxyIn covariance between the left view of stereo pairs and an image block of amendment right view image Covariance.C1And C2For the constant greater than zero, preventing denominator is zero;
Step (3.3) takes partial structurtes in its k width structural similarity figure for each pixel (x, y) of left view The maximum width of similarity, corresponding marked as i, (i=1,2 ... k), then i*s is the corresponding parallax value of (x, y) pixel, note Record is d, to construct disparity map D.
The complete of the extraction of the view-based access control model notable feature according to patent refers to objective evaluation method for quality of stereo images, It is characterized in that the step (6) specifically:
For vision significance figure extracting method using the vision significance model (SR) of spectrum residual error, particular content is as follows:
Given piece image I (x, y), has:
Wherein, F () and F-1() is two-dimensional Fourier transform and its inverse transformation, and Re () expression takes real part operation, Angle () Expression takes argument operation, and S (x, y) is the Saliency maps obtained by composing residual error method, and g (x, y) is gauss low frequency filter, hn (f) it is local mean value filter, expression formula is as follows:
Wherein, σ is the standard deviation in probability distribution;
Vision significance figure is referred to and is distorted by the method for composing residual error to middle reference and distorted image, as the following formula Shown in method establish integration after vision significance figure;
Sf(x, y)=Max [Sref(x,y),Sdis(x,y)] (6-4)
Wherein, SrefAnd SdisThe respectively vision significance figure of middle reference and distorted image, SfFor the vision after integration Saliency maps.
The complete of the extraction of the view-based access control model notable feature according to patent refers to objective evaluation method for quality of stereo images, It is supported vector machine SVR training prediction in step (12) described in being characterized in that, obtains optimum prediction model specifically:
SVR training prediction technique specifically uses 5- folding cross validation to train and test model, concrete scheme are as follows:
Sample is randomly divided into mutually disjoint five parts by step (12.1), selects wherein four parts of progress SVR training to obtain Then remaining portion is applied to the model up by best model, obtain corresponding objective quality value come to subjective quality into Row prediction;
Step (12.2) repeats the operation of step (12.1) repeatedly, and all data result average values is taken to characterize The performance of proposed model;
Expression is as follows:
Q=SVR (Index1,Index2,…,Indexn) (12-1)
Wherein, Q is evaluating objective quality score.
Beneficial effects of the present invention:
The present invention assists to extract visual information feature by vision significance figure, and comprehensive visual information characteristics are to realize pair The mapping of stereo image quality is realized and is objectively evaluated to distortion stereo pairs quality.The experimental results showed that based on the present invention Proposed method has good consistency to the evaluation performance of stereo image quality and subjective assessment, is better than conventional stereo image Quality evaluating method.
Detailed description of the invention
Fig. 1 is that the present invention is based on the full principles with reference to objective evaluation method for quality of stereo images that vision notable feature is extracted Figure.
Specific embodiment
The method of the present invention is described further with reference to the accompanying drawing.
Step (1) successively reads in the 3D LIVE image data of texas,U.S university Austin using Matlab software The reference stereo pairs of stage I and stage II and corresponding distortion stereo pairs in library, wherein each stereo pairs point It Bao Kuo not left and right view image.
Step (2) constructs Log Gabor filter model, carries out at convolution algorithm to the stereo pairs in step (1) Reason respectively obtains reference and is distorted the energy response figure of stereo image pair or so view;
The expression formula of Log Gabor filter is as follows:
Wherein, f0And θ0It is centre frequency and the azimuth of Log Gabor filter, σθAnd σfRespectively represent filter Azimuth bandwidth and radial bandwidth, f and θ respectively represent radial coordinate and the azimuth of filter.Wherein, σθ=π/18, σf= 0.75, f0=1/6, θ0=0, f=0, π/4, π/3,3 π/4, θ=0, π/5,2 π/5,3 π/5,4 π/5.Thus 4 × 5=20 is obtained The local energy of a LoG Gabor filter energy response figure, the response of Log Gabor filter is defined as the energy between each scale The maximum value of amount, and the local energy in each scale is defined as each azimuth and corresponds to the sum of local energy.
By Log Gabor filter and after referring to and being distorted stereo image pair or so view progress convolution, obtain corresponding Energy response figure, expression formula is as follows:
Wherein, I (x, y) is the left view or right view of reference and distortion stereo pairs,Convolution algorithm;
Step (3) extracts disparity map with distortion stereo pairs to the reference stereo pairs that step (1) inputs respectively;
The right view for the stereo pairs that step (4) inputs step (1) is according to the disparity map obtained in step (3) The level that parallax value carries out pixel moves to right, the calibration right view I that construction and left view pixel coordinate pair are answeredR((x+d), y), so Left view is obtained based on step (2) afterwards and calibrates the energy response figure of right view, calculates normalized left view weight map WL(x, Y) and calibration right view weight map WR((x+d), y), expression is as follows:
Wherein, FL(x, y) and FR((x+d), y) is respectively the energy sound of the left view that step (2) obtains and calibration right view The parallax value of respective coordinates in the disparity map D that Ying Tu, d are calculated for step (3);
The ginseng that the left view and step (4) of reference and distortion stereo pairs that step (5) is based in step (1) obtain Examine and be distorted stereo pairs calibration right view and normalized left view weight map and calibration right view weight map, utilize Binocular view Fusion Model is realized to the image co-registration of stereo-picture, and reference and distortion intermediate image is respectively obtained;Binocular The formula of view fusion is as follows:
CI (x, y)=WL(x,y)×IL(x,y)+WR((x+d),y)×IR((x+d),y) (5-1)
Wherein, CI (x, y) is the fused intermediate image of binocular view, IL(x, y) and IR((x+d), y) is respectively vertical The left view and calibration right view of body image pair;
The middle reference and distorted image that step (6) obtains step (5) extract reference and distortion vision significance respectively Figure, and it is integrated, the vision significance figure S after establishing integrationf
The disparity map of reference stereo pairs and distortion stereo pairs that step (7) is obtained using step (3) extracts deep Characteristic information is spent, and measurement is made to the distortion level of the disparity map of distortion stereo pairs;Using the method for pixel domain error The similitude for extracting the depth characteristic information of reference and distortion stereo pairs, as reaction distortion stereo pairs in disparity map It improves quality the index of distortion level, expression formula is as follows:
Wherein, DrefRepresent the disparity map of reference picture, DdisThe disparity map of distorted image is represented, E () is mean function, ε For the constant greater than zero, preventing denominator is zero, ε=0.001, Index1And Index2It is two similitudes of depth characteristic information Measure Indexes;
The middle reference and distorted image that step (8) obtains step (5) extract edge and textural characteristics respectively;
Process of convolution is carried out by Prewitt operator and by altimetric image, obtains the gradient map comprising edge contour information, is utilized The expression formula of the marginal information feature of Prewitt operator extraction middle reference and distorted image is as follows:
Wherein, f (x, y) is the left/right view of stereo pairs,For convolution algorithm, hxAnd hyIt is 3 × 3 Prewitt Vertical formwork and horizontal shuttering are respectively intended to the horizontal edge and vertical edge of detection image.Template expression formula is as follows:
The extraction of texture information feature uses local binary patterns LBP, and the expression formula of LBP is as follows:
Wherein, gcIt is the gray value of the central pixel point of image, gpIt is the gray value of the neighbor pixel of image, x and y generation The coordinate value of table central pixel point.Sgn (x) is jump function.
The visual information feature and step (6) for the middle reference and distorted image that step (9) extracts step (8) are established The multiplication put pixel-by-pixel of vision significance figure, obtain the visual information feature of vision significance enhancing, expression It is as follows:
GMSR(x, y)=GMR(x,y)*Sf(x,y) GMSD(x, y)=GMD(x,y)*Sf(x,y) (9-1)
TISR(x, y)=TIR(x,y)*Sf(x,y) TISD(x, y)=TID(x,y)*Sf(x,y) (9-2)
ISR(x, y)=IR(x,y)*Sf(x,y) ISD(x, y)=ID(x,y)*Sf(x,y) (9-3)
Wherein, GMR、TIRAnd IRIt is the edge, texture and brightness information of middle reference image, GM respectivelyD、TIDAnd ID It is the edge, texture and brightness information of intermediate distorted image respectively;SfVision after the integration obtained for step (6) is significant Property figure;
Step (10) carries out similarity measurement, expression to the visual information feature for the conspicuousness enhancing extracted in step (9) Formula is as follows:
Wherein, GMSR、TISRAnd ISRIndicate that edge, texture and the luminance information of the conspicuousness enhancing of middle reference image are special Sign, GMSD、TISDAnd ISDIndicate edge, texture and the luminance information of the conspicuousness enhancing of intermediate distorted image, Index3、Index4 And Index5Respectively represent the similarity measurements figureofmerit at edge, texture and luminance information feature, C4It is a constant greater than zero, It is zero, C the purpose is to prevent denominator4=0.5.
The middle reference and distorted image that step (11) obtains step (5) carry out down-sampled processing, obtain L scale Middle reference and distorted image, L=3.To under L scale space middle reference and the same applying step of distorted image (6), (9) and the method for (10) carries out the foundation of vision significance figure, the extraction of visual signature and similarity measurement, is always obtained N number of Similarity measurements figureofmerit, then N=2L+2, then, and N=8.
Down-sampled method is as follows: input piece image obtains filtering image by low-pass filter, then schemes to filtering As carry out decimation factor be m down-sampled processing, m=2, obtain it is down-sampled after image.
Each Measure Indexes obtained in step (12) integration step (8) and (11) are supported vector machine SVR training Prediction obtains optimum prediction model, and is mapped as the objective assessment score of picture quality.
Wherein, what the view-based access control model notable feature according to patent was extracted is complete with reference to the stereo image quality side of objectively evaluating Method, it is characterised in that the step (3) includes the following steps:
Step (3.1) will be referred to respectively and the right view all pixels point level of distortion stereo image pair moves to right k times, The step-length moved every time is s pixel, the k width amendment right view I after obtaining horizontal move to rightR((x+i*s), y), (i=1,2 ... K), in this s=1, k=25.Each width amendment right view is corresponding marked as i, and (i=1,2 ... k).
Step (3.2) calculates separately the left view of stereo image pair using structural similarity (SSIM) algorithm and k width is repaired The structural similarity of positive right view, obtains k width structural similarity figure.SSIM algorithm expression formula is as follows:
Wherein, μxAnd μyRespectively indicate a corresponding image in the left view and amendment right view image of stereo pairs Mean value in block;σxAnd σyRespectively indicate a corresponding image block in the left view and amendment right view image of stereo pairs Interior variance yields;σxyIn covariance between the left view of stereo pairs and an image block of amendment right view image Covariance.C1And C2For the constant greater than zero, preventing denominator is zero, in this C1=6.5025, C2=58.5225.
Step (3.3) takes partial structurtes in its k width structural similarity figure for each pixel (x, y) of left view The maximum width of similarity, corresponding marked as i, (i=1,2 ... k), then i*s is the corresponding parallax value of (x, y) pixel, note Record is d, to construct disparity map D.
The complete of the extraction of the view-based access control model notable feature according to patent refers to objective evaluation method for quality of stereo images, It is characterized in that the step (6) specifically:
For vision significance figure extracting method using the vision significance model (SR) of spectrum residual error, particular content is as follows:
Given piece image I (x, y), has:
Wherein, F () and F-1() is two-dimensional Fourier transform and its inverse transformation, and Re () expression takes real part operation, Angle () Expression takes argument operation, and S (x, y) is the Saliency maps obtained by composing residual error method, and g (x, y) is gauss low frequency filter, hn (f) it is local mean value filter, expression formula is as follows:
Wherein, σ is the standard deviation in probability distribution, σ=1.5;
Vision significance figure is referred to and is distorted by the method for composing residual error to middle reference and distorted image, as the following formula Shown in method establish integration after vision significance figure;
Sf(x, y)=Max [Sref(x,y),Sdis(x,y)] (6-4)
Wherein, SrefAnd SdisThe respectively vision significance figure of middle reference and distorted image, SfFor the vision after integration Saliency maps.
The complete of the extraction of the view-based access control model notable feature according to patent refers to objective evaluation method for quality of stereo images, It is supported vector machine SVR training prediction in step (12) described in being characterized in that, obtains optimum prediction model specifically:
SVR training prediction technique specifically uses 5- folding cross validation to train and test model, concrete scheme are as follows:
Sample is randomly divided into mutually disjoint five parts by step (12.1), selects wherein four parts of progress SVR training to obtain Then remaining portion is applied to the model up by best model, obtain corresponding objective quality value come to subjective quality into Row prediction;
Step (12.2) repeats the operation of step (12.1) repeatedly, and all data result average values is taken to characterize The performance of proposed model;
Expression is as follows:
Q=SVR (Index1,Index2,…,Indexn) (12-1)
Wherein, Q is evaluating objective quality score.

Claims (4)

1. a kind of view-based access control model notable feature is extracted complete with reference to objective evaluation method for quality of stereo images, it is characterised in that including Following steps:
Step (1) input is with reference to stereo pairs and distortion stereo pairs, wherein each stereo pairs respectively include left view Figure and right view image;
Step (2) constructs Log Gabor filter model, carries out convolution algorithm processing to the stereo pairs in step (1), It respectively obtains reference and is distorted the energy response figure of stereo image pair or so view;
The expression formula of Log Gabor filter is as follows:
Wherein, f0And θ0It is centre frequency and the azimuth of Log Gabor filter, σθAnd σfRespectively represent the azimuth of filter Bandwidth and radial bandwidth, f and θ respectively represent radial coordinate and the azimuth of filter;
By Log Gabor filter and after referring to and being distorted stereo image pair or so view progress convolution, corresponding energy is obtained Response diagram is measured, expression formula is as follows:
Wherein, I (x, y) is the left view or right view of reference and distortion stereo pairs,For convolution algorithm;
Step (3) extracts disparity map with distortion stereo pairs to the reference stereo pairs that step (1) inputs respectively;
The right view for the stereo pairs that step (4) inputs step (1) according to the disparity map obtained in step (3) parallax The level that value carries out pixel moves to right, the calibration right view I that construction and left view pixel coordinate pair are answeredR((x+d), y), then base Left view is obtained in step (2) and calibrates the energy response figure of right view, calculates normalized left view weight map WL(x, y) and Calibrate right view weight map WR((x+d), y), expression is as follows:
Wherein, FL(x, y) and FR((x+d), y) is respectively the energy response of the left view that step (2) obtains and calibration right view Scheme, the parallax value of respective coordinates in the disparity map D that d is calculated for step (3);
Reference that step (5) is based in step (1) and be distorted stereo pairs left view and the obtained reference of step (4) and The calibration right view of distortion stereo pairs and normalized left view weight map and calibration right view weight map, utilize binocular View Fusion Model is realized to the image co-registration of stereo-picture, and reference and distortion intermediate image is respectively obtained;Binocular view The formula of fusion is as follows:
CI (x, y)=WL(x,y)×IL(x,y)+WR((x+d),y)×IR((x+d),y) (5-1)
Wherein, CI (x, y) is the fused intermediate image of binocular view, IL(x, y) and IR((x+d), y) is respectively perspective view The left view and calibration right view of picture pair;
The middle reference and distorted image that step (6) obtains step (5) extract reference and distortion vision significance figure respectively, And it is integrated, the vision significance figure S after establishing integrationf
It is special that the disparity map of reference stereo pairs and distortion stereo pairs that step (7) is obtained using step (3) extracts depth Reference breath, and measurement is made to the distortion level of the disparity map of distortion stereo pairs;It is extracted using the method for pixel domain error With reference to and distortion stereo pairs depth characteristic information similitude, as reaction be distorted stereo pairs matter on disparity map The index of distortion level is measured, expression formula is as follows:
Wherein, DrefRepresent the disparity map of reference picture, DdisThe disparity map of distorted image is represented, E () is mean function, and ε is big In zero constant, preventing denominator is zero, Index1And Index2It is two similarity measurements figureofmerits of depth characteristic information;
The middle reference and distorted image that step (8) obtains step (5) extract edge and textural characteristics respectively;
Process of convolution is carried out by Prewitt operator and by altimetric image, obtains the gradient map comprising edge contour information, is utilized The expression formula of the marginal information feature of Prewitt operator extraction middle reference and distorted image is as follows:
Wherein, f (x, y) is the left/right view of stereo pairs,For convolution algorithm, hxAnd hyBe 3 × 3 Prewitt it is vertical Template and horizontal shuttering are respectively intended to the horizontal edge and vertical edge of detection image, and template expression formula is as follows:
The extraction of texture information feature uses local binary patterns LBP, and the expression formula of LBP is as follows:
Wherein, gcIt is the gray value of the central pixel point of image, gpIt is the gray value of the neighbor pixel of image, during x and y are represented The coordinate value of imago vegetarian refreshments, sgn (x) are jump functions;
The view that the visual information feature and step (6) for the middle reference and distorted image that step (9) extracts step (8) are established Feel the multiplication that Saliency maps are put pixel-by-pixel, obtain the visual information feature of vision significance enhancing, expression is as follows:
GMSR(x, y)=GMR(x,y)*Sf(x,y) GMSD(x, y)=GMD(x,y)*Sf(x,y) (9-1)
TISR(x, y)=TIR(x,y)*Sf(x,y) TISD(x, y)=TID(x,y)*Sf(x,y) (9-2)
ISR(x, y)=IR(x,y)*Sf(x,y) ISD(x, y)=ID(x,y)*Sf(x,y) (9-3)
Wherein, GMR、TIRAnd IRIt is the edge, texture and brightness information of middle reference image, GM respectivelyD、TIDAnd IDRespectively It is the edge, texture and brightness information of intermediate distorted image;SfVision significance after the integration obtained for step (6) Figure;
Step (10) carries out similarity measurement to the visual information feature for the conspicuousness enhancing extracted in step (9), and expression formula is such as Under:
Wherein, GMSR、TISRAnd ISRIndicate edge, texture and the luminance information feature of the conspicuousness enhancing of middle reference image, GMSD、TISDAnd ISDIndicate edge, texture and the luminance information of the conspicuousness enhancing of intermediate distorted image, Index3、Index4With Index5Respectively represent the similarity measurements figureofmerit at edge, texture and luminance information feature, C4It is a constant greater than zero, Purpose is that prevent denominator be zero;
The middle reference and distorted image that step (11) obtains step (5) carry out down-sampled processing, obtain in L scale Between refer to and distorted image, to the middle reference and the same applying step of distorted image (6), (9) and (10) under L scale space Method carry out the foundation of vision significance figure, the extraction of visual signature and similarity measurement, N number of similarity measurement is always obtained Index, then N=2L+2;
Down-sampled method is as follows: input piece image, filtering image is obtained by low-pass filter, then to filtering image into Row decimation factor be m down-sampled processing, obtain it is down-sampled after image;
Each Measure Indexes obtained in step (12) integration step (8) and (11) are supported vector machine SVR training prediction, Optimum prediction model is obtained, and is mapped as the objective assessment score of picture quality.
2. view-based access control model notable feature according to claim 1 is extracted complete with reference to the stereo image quality side of objectively evaluating Method, it is characterised in that the step (3) includes the following steps:
Step (3.1) will be referred to respectively and the right view all pixels point level of distortion stereo image pair moves to right k times, every time Mobile step-length is s pixel, the k width amendment right view I after obtaining horizontal move to rightR((x+i*s), y), i=1,2 ... k, often One width correct right view it is corresponding marked as i, i=1,2 ... k;
Step (3.2) calculates separately the left view of stereo image pair using structural similarity algorithm SSIM and k width corrects right view The structural similarity of figure obtains k width structural similarity figure, and SSIM algorithm expression formula is as follows:
Wherein, μxAnd μyIt respectively indicates in the left view and amendment right view image of stereo pairs in a corresponding image block Mean value;σxAnd σyIt respectively indicates in the left view and amendment right view image of stereo pairs in a corresponding image block Variance yields;σxyThe association side in covariance between the left view of stereo pairs and an image block of amendment right view image Difference, C1And C2For the constant greater than zero, preventing denominator is zero;
Step (3.3) takes partial structurtes in its k width structural similarity figure similar each pixel (x, y) of left view Property the maximum width of value, corresponding marked as i, i=1,2 ... k, then i*s is the corresponding parallax value of (x, y) pixel, be recorded as d, To construct disparity map D.
3. view-based access control model notable feature according to claim 1 is extracted complete with reference to the stereo image quality side of objectively evaluating Method, it is characterised in that the step (6) specifically:
For vision significance figure extracting method using the vision significance model (SR) of spectrum residual error, particular content is as follows:
Given piece image I (x, y), has:
Wherein, F () and F-1() is two-dimensional Fourier transform and its inverse transformation, and Re () expression takes real part operation, and Angle () is indicated Argument operation is taken, S (x, y) is the Saliency maps obtained by composing residual error method, and g (x, y) is gauss low frequency filter, hn(f) It is local mean value filter, expression formula is as follows:
Wherein, σ is the standard deviation in probability distribution;
Vision significance figure is referred to and is distorted by the method for composing residual error to middle reference and distorted image, it is shown as the following formula Method establish integration after vision significance figure;
Sf(x, y)=Max [Sref(x,y),Sdis(x,y)] (6-4)
Wherein, SrefAnd SdisThe respectively vision significance figure of middle reference and distorted image, SfFor the vision significance after integration Figure.
4. view-based access control model notable feature according to claim 1 is extracted complete with reference to the stereo image quality side of objectively evaluating Method, it is characterised in that be supported vector machine SVR training prediction in the step (12), it is specific to obtain optimum prediction model Are as follows:
SVR training prediction technique specifically uses 5- folding cross validation to train and test model, concrete scheme are as follows:
Sample is randomly divided into mutually disjoint five parts by step (12.1), and it is best to obtain to select wherein four parts of progress SVR training Then remaining portion is applied to the model up by model, corresponding objective quality value is obtained to carry out in advance subjective quality It surveys;
Step (12.2) repeats the operation of step (12.1) repeatedly, and all data result average values is taken to be mentioned to characterize The performance of model out;
Expression is as follows:
Q=SVR (Index1,Index2,…,Indexn) (12-1)
Wherein, Q is evaluating objective quality score.
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