CN104333751B - The parallel shooting method for objectively evaluating of stereoscopic camera based on three-dimensional disturbance - Google Patents

Abstract

The present invention relates to a kind of stereoscopic camera based on three-dimensional disturbance parallel shooting method for objectively evaluating: three-dimensional shape distortion μ when choosing stereoscopic camera parallel shooting _pas an objective evaluation index of stereo pairs; Set up L _bwith d _ccorrelation k _p, with k _pas the comprehensive interactional objective evaluation index analyzing shooting distance and camera spacing; Stereoscopic camera is utilized to take stereo pairs in the situation of be arrangeding in parallel; Extract camera shooting distance L when stereoscopic camera is parallel to be taken _b, camera spacing d _cwith camera focus f; Calculate the objective evaluation index μ of stereo-picture _pand k _p, form a three-dimensional perception ε of final index _p, further by ε _pbe combined with camera focus f; Obtaining final objective evaluation index-ρ is the objective comprehensive evaluation index of parallel camera, and value more hour, illustrates that the parallel shooting quality of this stereoscopic camera is better.The present invention well can be applied to the quality evaluation of stereo-picture, evaluation result and subjective evaluation result correlation very strong.

Description

The parallel shooting method for objectively evaluating of stereoscopic camera based on three-dimensional disturbance

Technical field

The invention belongs to three-dimensional image acquisition technical field, be specifically related to the parallel shooting evaluation method of a kind of new stereoscopic camera.

Background technology

As everyone knows, image technique relates to each large fields such as amusement, industry, military affairs, is the indispensable important technology of scientific technological advance and world's progress.Nowadays, traditional two dimensional image can not be satisfied the demand, and new stereo-picture technology is used widely.Compared to two dimensional image, stereo-picture presses close to the true picture that human eye captures more, adds depth perception and the sense of reality, can reappear real scene more exactly.But, stereo-picture is in the process gathering, store, transmit, compress and show, due to the error of algorithm and equipment itself, inevitably can produce the distortion of each middle various kinds, as trapezoidal distortion, poly-loose conflict, theater effect, cardboard effect etc., so how to weigh out the impact of these distortion stereoscopic image quality exactly, become the emphasis topic of 3D (threedimensional, 3D) area research.In stereo-picture assessment technique research field, most people is placed on research emphasis in stereo image information loss degree, and the distortion level namely in stereo-picture a series of end processing sequences after collection, few people have the evaluation to original three-dimensional image in mind.In stereo-picture acquisition system, main application be the method for the left and right visual pattern superposition of simulation human eye system, in this process, relate to many parameters, as distance between axles, angle of visibility etc. in camera focus, shooting distance, camera, therefore, how reasonably to use these parameters to form stereoscopic camera QA system, just become research emphasis of the present invention to instruct stereoscopic shooting.

Stereo image quality evaluation method can be divided into subjective evaluation method and method for objectively evaluating.Subjective evaluation method is dominated by people, and namely the information that comprises of human eye subjective perception stereo-picture, judges the quality of stereo-picture with this; Method for objectively evaluating refers to some feature in the process produced according to stereo-picture itself or stereo-picture, thus calculates and derive and the evaluation points that draws and formula, can formation algorithm or model, and then by programming realization.Quality due to stereo-picture is all finally judged by human eye, so subjective evaluation method is the most reliable method.But subjective assessment complex steps, expend time in length, and the individual difference of subject (people) is large, easily there is fluctuation in subjective scores, and method for objectively evaluating efficiency is higher, operability is better, the more important thing is and can realize automatic Evaluation system, so the range of application of subjective evaluation method is extensive not as method for objectively evaluating.If obtain evaluation index comparatively accurately, subjective assessment is absolutely necessary, therefore, the present invention is on the basis proposing the parallel shooting criterion of stereoscopic camera, also deeper research is carried out further in conjunction with existing three-dimensional disturbance, utilize subjective experiment to verify, thus draw the shooting standard with universality.

Summary of the invention

Technical problem to be solved by this invention is: propose the parallel shooting method for objectively evaluating of a kind of stereoscopic camera, effectively can evaluate the stereo image quality of the parallel shooting of stereoscopic camera, and can provide shooting criterion for stereoscopic shooting amateurs.Technical solution of the present invention is as follows:

The parallel shooting quality method for objectively evaluating of a kind of stereoscopic camera, involved symbol and implication as shown in the table:

The method comprises and comprising the following steps:

1) set subjective assessment value as MOS, determine the evaluation standards of grading of stereoscopic camera shooting quality;

2) according to subjective experiment result, three-dimensional shape distortion μ when choosing stereoscopic camera parallel shooting _pan objective evaluation index as stereo pairs:

${\mathrm{\μ}}_p=\frac{L_s\·\tan (\mathrm{\β}/2)}{f\·\tan (\mathrm{\α}/2)}$

3) according to subjective experiment result, L is set up _bwith d _ccorrelation k _p, with k _pas the comprehensive interactional objective evaluation index analyzing shooting distance and camera spacing:

k _p＝d _c-0.000054·L _b ^1.6

4) stereoscopic camera is utilized to take stereo pairs in the situation of be arrangeding in parallel;

5) according to captured stereo pairs, camera shooting distance L when stereoscopic camera is parallel to be taken is extracted _b, camera spacing d _cwith camera focus f;

6) the objective evaluation index μ of stereo-picture is calculated _pand k _p, form a three-dimensional perception ε of final index _p, further by ε _pbe combined with camera focus f;

${\mathrm{\ϵ}}_p=\frac{{\mathrm{\μ}}_p\·f\·k_p}{100\·d_e}=\frac{L_s\·\tan (\mathrm{\α}/2)\·(d_c-0.000054\·{L_b}^{1.6})}{100\·d_e\·\tan (\mathrm{\β}/2)}$

ε _p＝ρ·f ^-1.9-20

7) final objective evaluation index is obtained---ρ is the objective comprehensive evaluation index of parallel camera, and parallel camera objective comprehensive evaluation index ρ value more hour, illustrates that the parallel shooting quality of this stereoscopic camera is better:

$\mathrm{\ρ}=(\frac{L_s\·\tan (\mathrm{\α}/2)\·(d_c-0.000054\·{L_b}^{1.6})}{100\·d_e\·\tan (\mathrm{\β}/2)}+20)\·f^{1.9}.$

The present invention's advantage is compared with prior art: the present invention utilizes double vision point stereo pairs to extract the inner parameter of stereoscopic camera, external parameter and scenario parameters, by subjective detection test stereoscopic image to making subjective assessment, based on the feature of the parallel shooting of stereoscopic camera and the requirement to acquisition parameters, the three-dimensional disturbance of abundant research is on the impact of three-dimensional shooting effect, set up the parallel shooting criterion of a kind of new stereoscopic camera, the stereoeffect of stereo-picture and picture quality when the method can evaluate the parallel shooting of stereoscopic camera effectively, and take criterion accordingly for the amateur of stereoscopic shooting provides.

Accompanying drawing explanation

Describe embodiments of the present invention in detail by referring to accompanying drawing, above feature and advantage of the present invention will be easy to become obvious for those skilled in the art, wherein:

Fig. 1 is the parallel schematic diagram of stereoscopic camera, and (a) takes schematic diagram, and (b) watches schematic perspective view;

Fig. 2 is stereoscopic camera parallel shooting quality objective evaluation model;

Fig. 3 is L _bwith d _ccorrelation schematic diagram;

Fig. 4 is ε _pwith f correlation schematic diagram.

Embodiment

In further detail embodiments of the present invention are described hereinafter with reference to accompanying drawing now.But, specifically can implement the present invention by different forms and the present invention should be interpreted as be limited to execution mode set forth herein.More precisely, provide these execution modes to be comprehensive and complete in order to expose, and idea of the present invention will be passed on to those skilled in the art all sidedly.

The present invention only studies for the parallel shooting of stereoscopic camera, in conjunction with the feature (as Fig. 1) when the shooting of parallel camera and stereo-picture viewing and existing shooting criterion, probe into and extend multiple stereoscopic camera acquisition parameters to the impact of picture quality, and establish corresponding model.Simultaneously in conjunction with the basis of the restriction of the scenario parameters of parallel shooting and the analysis and research of three-dimensional disturbance, propose the parallel shooting criterion of new a kind of stereoscopic camera.

For the parallel shooting of stereoscopic camera, the present invention is based on three-dimensional disturbance and establish a kind of new stereoscopic camera parallel shooting criterion model with subjective assessment, as shown in Figure 2.First, the acquisition parameters of stereoscopic camera is obtained from stereo image pair, by parameters input to parallel camera shooting quality evaluation module, existing shooting criterion, the evaluation index of effectively avoiding the rule of three-dimensional disturbance and the present invention to propose are combined, and export corresponding objective evaluation value, by the contrast of this objective evaluation value and subjective assessment value MOS, can learn that shooting criterion that the present invention proposes is applicable to the evaluation to three-dimensional camera parallel shooting quality.Concrete implementation step is as follows:

(1) stereoscopic camera acquisition parameters is obtained from stereogram image source

Stereoscopic camera parameter extraction acceptance of the bid earnest method mainly at world coordinate system, set up transformational relation model between camera coordinates system and image coordinate system.Have the method for multiple extracting parameter in prior art, the present invention adopts vanishing point method to extract shooting distance L _b, camera focus f and camera spacing d _c.The specific implementation of method can see two sections of documents below:

[1]JA.deFranca,MR.Stemmer,MBD.Franca,Anewrobustalgorithmicformulti-cameracalibrationwitha1Dobjectunder[J].PatternRecognition,45(10),3636-3647,2012.

[2]E.Guillou,D.Meneveaux,E.Maisel,andK.Bouatouch,Usingvanishingpointsforcameracalibrationandcoarse3Dreconstructionfromasingleimage[J].VisualComputer,16(7),396-410,2000.

The present invention extracts stereoscopic camera inside and outside parameter by hyperspace sampling analytic method founding mathematical models and optimal estimation parameter model two steps, and the area-of-interest exacting method of combining image visual stimulus, and extract scenario parameters with this.The method adopts interactively mode, top-down information is converted to the different weighted values of input picture low-level image feature, simultaneously in conjunction with Itti-Koch model and Stentiford model, realizes the area-of-interest exacting method of combining image visual stimulus.

(2) the present invention is based on forefathers to part camera parameter and the research of stereoeffect relation, according to achievement in research and conclusions such as Percival comfort zone, A Enshacikaya stereo formula and Bercovitz formula, in conjunction with human eye corresponding circle of sensation comfort zone, by subjectivity detection experiment, correlation between the parallel acquisition parameters of research stereoscopic camera, based on three-dimensional disturbance and subjective assessment analysis and summary, the parallel shooting criterion of a kind of new stereoscopic camera of proposition.The symbol related in formula and implication as shown in table 1.

Symbol in table 1 formula and implication thereof

Because objective evaluation model proposed by the invention is set up on a large amount of subjective experiment basis, therefore, the present invention carries out subjective experiment by according to Pyatyi evaluation criterion (table 2) general at present.And the output of objective evaluation model method subjective evaluation result and the present invention proposed contrasts, and verifies exploitativeness of the present invention with this.

Table 2 stereoscopic camera close-up photography quality evaluation standards of grading

Will from following three aspect researchs this shooting criterion:

(2.1) three-dimensional shape distortion

Weigh stereo-picture distortion level directly and effective way is width magnification ratio and degree of depth magnification ratio [3].Width magnification ratio (M _w) refer to the ratio of wide (or high) of 3D (three-dimensional, the 3D) object of reproduction and original 3D object wide (or high).In like manner, degree of depth magnification ratio (M _d) refer to the ratio of the degree of depth of the 3D object of reproduction and the degree of depth of original 3D object.The people such as Zilly propose three-dimensional shape distortion be a kind of simple means of interpretation to show the distortion degree of stereo-picture, three-dimensional shape distortion can be expressed as the ratio of width magnification ratio and degree of depth magnification ratio, shown in (1).

$\mathrm{\μ}=\frac{M_w}{M_d}=\frac{L_s\·d_c}{L_c\·\mathrm{\ξ}-L_b\·(\mathrm{\ξ}-d_e)}$

Wherein, $\mathrm{\ξ}=\frac{a_1\·f\·d_c}{L_c}---\left(1\right)$

A in formula ₁refer to screen magnifying rate, the ratio of the width of the virtual screen felt when namely the width of screen and observer watch image, formula is as follows:

$a_1=\frac{\tan (\mathrm{\β}/2)}{\tan (\mathrm{\α}/2)}---\left(2\right)$

By the design standard (as shown in Figure 1) of parallel camera, camera skew (Sensorshift) is the side-play amount of the convergence from the center of image to lens axis:

$S=\frac{f\·d_c}{2\·L_c}---\left(3\right)$

Under parallel camera configuration, when undistorted stereo scene is presented near stereoscopic screen, experimentally condition, now S=d _e/ (2a ₁), then formula (3) can be reduced to formula (4), and subjective results is as shown in table 3.

${\mathrm{\μ}}_p=\frac{L_s}{a_1\·f}=\frac{L_s\·\tan (\mathrm{\β}/2)}{f\·\tan (\mathrm{\α}/2)}---\left(4\right)$

Table 3 μ _pwith the corresponding relation of MOS

[3]ZillyF,KlugerJ,KauffP.Productionrulesforstereoacquisition[J].ProceedingsoftheIEEE,2011,99(4):590-606.

(2.2) shooting formula---the L of the present invention's proposition _b, d _crelational expression

So far, the basis shooting formula about stereoscopic camera shooting has a lot, but seldom can clearly express shooting distance L _bwith camera spacing d _caffect the corresponding relation of shooting quality.By a series of subjective and objective experiment, first by L _bas fixed value, choose d _cscope is from 10mm to 400mm, and stepping is 10mm; Secondly, L is changed _bvalue, d _cdo equally and change.According to subjectivity detection experiment, we obtain L _bwith d _ccorrelation schematic diagram, as shown in Figure 3.

So, L _bwith d _ccorrelation formula such as formula shown in (5).

d _c＝0.000054·L _b ^1.6+k _p(5)

In figure 3, k _prepresent constant, have after result of the test matching: k _p" d in=63.2 representative graphs 3 _cvsL _b(1) ", the line of demarcation of representative " MOS=5 " and " MOS=4 ", k _p" d in=102.5 representative graphs 3 _cvsL _b(2) ", the line of demarcation of representative " MOS=4 " and " MOS=3 ", k _p" d in=135.7 representative graphs 3 _cvsL _b(3) ", the line of demarcation of representative " MOS=3 " and " MOS=2 ", k _p" d in=159.1 representative graphs 3 _cvsL _b(4) line of demarcation of " MOS=2 " and " MOS=1 " ", is represented.

Formula (5) is converted to following form:

k _p＝d _c-0.000054·L _b ^1.6(6)

Subjective experiment result is as shown in table 4.

Table 4k _pwith the corresponding relation of MOS

(3) in order to the parameter in stereoscopic camera camera system can be controlled, two parts research contents in step (2) is arranged and combines, form a three-dimensional perception ε of final index _p(as shown in Equation 7), μ _pfor three-dimensional shape distortion, k _pfor the L that the present invention proposes _b, d _crelational expression.

${\mathrm{\ϵ}}_p=\frac{{\mathrm{\μ}}_p\·f\·k_p}{100\·d_e}=\frac{L_s\·\tan (\mathrm{\α}/2)\·(d_c-0.000054\·{L_b}^{1.6})}{100\·d_e\·\tan (\mathrm{\β}/2)}---\left(7\right)$

In order to enrich index ε further _p, the present invention has carried out again the research about camera focus f, and experimental result as shown in Figure 4.Can obtain thus, index ε _pformula (8) can be had to represent with the relational expression of f.

ε _p＝ρ·f ^-1.9-20(8)

Evaluate for parallel camera shooting quality, ρ is the objective comprehensive evaluation index of parallel camera (as shown in Equation 9).

$\mathrm{\ρ}=(\frac{L_s\·\tan (\mathrm{\α}/2)\·(d_c-0.000054\·{L_b}^{1.6})}{100\·d_e\·\tan (\mathrm{\β}/2)}+20)\·f^{1.9}---\left(9\right)$

From formula 9 and Fig. 4, the value of the objective indicator ρ finally proposed as the present invention more hour, illustrates that the parallel shooting quality of this stereoscopic camera is better.

The objective evaluation model of foundation proposed by the invention not only achieves the evaluation to three-dimensional camera parallel shooting quality, but also may be used for instructing the parallel shooting of stereoscopic camera low coverage, for amateur provides the foundation that rationally arranges acquisition parameters.

The content be not described in detail in specification of the present invention belongs to the known prior art of professional and technical personnel in the field.

Claims (1)

1. based on the parallel shooting method for objectively evaluating of stereoscopic camera of three-dimensional disturbance, involved symbol and implication as shown in the table:

The method comprises the following steps:

1) set subjective assessment value as MOS, determine the evaluation standards of grading of stereoscopic camera shooting quality;

2) according to objective and subjective experiment result, when choosing stereoscopic camera parallel shooting, three-dimensional shape distorts μ _pan objective evaluation index as stereo pairs:

3) according to subjective experiment result, L is set up _bwith d _ccorrelation k _p, with k _pas the comprehensive interactional objective evaluation index analyzing shooting distance and camera spacing:

k _p＝d _c-0.000054·L _b ^1.6

4) stereoscopic camera is utilized to take stereo pairs in the situation of be arrangeding in parallel;

5) according to captured stereo pairs, camera shooting distance L when stereoscopic camera is parallel to be taken is extracted _b, camera spacing d _cwith camera focus f;

6) the objective evaluation index μ of stereo-picture is calculated _pand k _p, form a three-dimensional perception ε of final index _p, further by ε _pbe combined with camera focus f;

ε _p＝ρ·f ^-1.9-20

7) final objective evaluation index is obtained---ρ is the objective comprehensive evaluation index of parallel camera, and parallel camera objective comprehensive evaluation index ρ value more hour, illustrates that the parallel shooting quality of this stereoscopic camera is better: