CN109359531A - Fruit harvesting area automatic positioning method facing natural scene - Google Patents

Fruit harvesting area automatic positioning method facing natural scene Download PDF

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CN109359531A
CN109359531A CN201811062603.9A CN201811062603A CN109359531A CN 109359531 A CN109359531 A CN 109359531A CN 201811062603 A CN201811062603 A CN 201811062603A CN 109359531 A CN109359531 A CN 109359531A
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fruit
pixel
centre
region
neighborhood
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CN109359531B (en
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庄家俊
唐宇
骆少明
侯超钧
郭琪伟
苗爱敏
陈亚勇
张恒涛
刘泽锋
孙胜
朱耀宗
高升杰
程至尚
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Zhongkai University of Agriculture and Engineering
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    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06VIMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
    • G06V20/00Scenes; Scene-specific elements
    • G06V20/60Type of objects
    • G06V20/64Three-dimensional objects
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06TIMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T5/00Image enhancement or restoration
    • G06T5/77Retouching; Inpainting; Scratch removal
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06TIMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00Indexing scheme for image analysis or image enhancement
    • G06T2207/10Image acquisition modality
    • G06T2207/10028Range image; Depth image; 3D point clouds
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06TIMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00Indexing scheme for image analysis or image enhancement
    • G06T2207/30Subject of image; Context of image processing
    • G06T2207/30181Earth observation
    • G06T2207/30188Vegetation; Agriculture

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  • General Physics & Mathematics (AREA)
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Abstract

The invention relates to a natural scene-oriented automatic positioning method for a fruit harvesting area, which comprises the following steps: extracting litchi fruit areas in the training data, counting weighted tricolor brightness distribution characteristics of the litchi fruit areas as objective brightness reference, and enhancing weighted tricolor brightness components by adopting an iterative Retinex algorithm; extracting the fruit region with enhanced brightness by combining the corrected color difference map, thresholding treatment and mathematical morphology; reconstructing hue components in an HSI color space through the position relation of local neighborhood pixels and hue information, and extracting branch regions according to hue distribution characteristics; the branch framework is extracted by adopting a thinning algorithm, the key angular points on the framework are extracted through angular point detection and the mode distribution rule of angular point neighborhood pixels, and the litchi fruit harvesting area is automatically positioned by combining the relative position constraint of the fruits and the branches and the spatial distribution characteristic of the key angular points. The method can improve the adaptivity and the accuracy of automatic positioning of the litchi fruit harvesting area in a natural scene.

Description

A kind of fruit harvesting region automatic positioning method towards natural scene
Technical field
The present invention relates to IT application to agriculture, precision agriculture, machine vision and technical field of image processing, and in particular to a kind of Fruit harvesting region automatic positioning method towards natural scene.
Background technique
Modern orchard gradually appears the status that management cost is constantly incremented by, manual labor constantly successively decreases, close with labour Picking fruit mode based on collection type gradually shows trend (the Gongal A., Amatya of sustainable developability reduction S.,Karkee M.,et al,2015.Sensors and systems for fruit detection and localiza tion.Comput.Electron.Agric.116,8-19).The intelligent harvesting equipment of fruit is a kind of traditional artificial side of change The automated job of formula is equipped, and the critical components such as mobile platform, control system, the detection of woods fruit and end effector are generally included, For step by step input into the automatic recovery operations of a variety of mountain area woods fruits, the main problem that it is faced has been nature into slice at present The reliable detection with harvesting point/region accurate positionin in fruit region under part.
Fruit detection generallys use machine vision and image processing techniques with harvesting point/zone location.For natural scene Influence of the middle forest fruit regional imaging quality vulnerable to illumination condition, (Xu L.M., the Lv J.D., 2018.Recognition such as Xu method for apple fruit based on SUSAN and PCNN.Multimed.Tools Appl.77(6), 7205-7219) using the fruit image acquired in the homographic filtering method processing weaker situation of illumination.Wang etc. (Wang C.L., Lee W.S,Zou X.J.,et al,2018.Detection and counting of immature green citrus fruit based on the Local Binary Patterns(LBP)feature using illumination- Normalized images.Precision Agric.17 (6), 678-697) use the Retinex algorithm based on bilateral filtering Improve the overall brightness in fruit region in image.But the above method does not consider the INTELLIGENT IDENTIFICATION of input picture illumination property, Processing brightness is higher or the more uniform image of Luminance Distribution is easy to appear " overexposure " phenomenon or changes the original in fruit region There is hue information, subsequent fruit region detection and harvesting point/zone location accuracy may be influenced, so being not suitable for certainly Woods fruit image under dynamic processing natural scene.Zhuang etc. (Zhuang J.J., Luo S.M., Hou C.J., et al, 2018.Detection of orchard citrus fruits using a monocular machine vision- based method for automatic fruit picking applications.Comput.Electron.Agric. 152,64-73) the even problem of uneven illumination of fruit area image has been automatically processed using local block homographic filtering method, but should Method includes more adjustment parameter, may need to readjust when environmental factor significantly changes, treatment process is relatively complicated. (Wang C.L., Zou X.J., Tang Y.C., et al, the 2016.Localisation of litchi in an such as Wang unstructured environment using binocular stereo vision.Biosyst.Eng.145,39-51) In conjunction with K- means Method and the method for registering based on tag template extracts the red litchi fruits in binocular vision image sequence There is preferable detection effect in region to the lesser woods fruit image of backcolor difference.Point is harvested for the lichee under pneumatic environment Orientation problem, (Xiong J.T., He Z.L., Lin R., et al, the 2018.Visual positioning such as Xiong technology of picking robots for dynamic litchi clusters with disturbance.Co Mput.Electron.Agric.151,226-237) the tone distributed knowledge based on litchi fruits region, using clustering algorithm from Mature litchi fruits region and its mass center are extracted in the chrominance component of HSI image, through pendulum criterion from binocular vision image Harvesting point is estimated, but automatic positioning error is larger, is suitable for the wider end effector of beta pruning job area.To avoid environment Influence of the factor to lichee harvesting spot placement accuracy, Xiong etc. (Xiong J.T., Lin R., Liu Z., et al, 2018.The recognition of litchi clusters and the calculation of picking point In a nocturnal natural environment.Biosyst.Eng.166,44-57) using based on LED orientation light filling Nighttime imaging system, non-woods fruit in night scenes image and interference limb region, knot are filtered out by fuzzy C-means clustering It closes Otsu Threshold segmentation and Harris corner detection approach orients the harvesting point of litchi fruits, this method is mainly for the treatment of preceding back The more significant night woods fruit image of scape difference.
Although currently based on the litchi fruits of machine vision and image processing techniques harvesting point/region automatic positioning method Achieved certain effect, but in the continually changing natural scene of environmental factor, more reliable, more accurate harvesting point or Region automatic positioning method is harvested to explore there is still a need for further.
Summary of the invention
The present invention provides one kind towards natural field to overcome at least one defect (deficiency) described in the above-mentioned prior art The fruit harvesting region automatic positioning method of scape, it is intended to improve fruit detection and harvesting zone location based on machine vision technique The adaptivity and accuracy of system.
To achieve the purpose of the present invention, it is achieved using following technical scheme:
A kind of fruit harvesting region automatic positioning method towards natural scene, comprising the following steps:
(1) the weighting three primary colors luminance component V for extracting current RGB image I, utilizes modified R X chromaticity difference diagram (Modified Red and Green/Blue (X) Chromatic Mapping, MRXCM) method generates modified R X (Red&Green/ from I Blue) chromaticity difference diagram Cm, from CmMiddle extraction part fruit region RoIs (Regions of Interest) calculates RoIs Luminance Distribution Statistical nature, Retinex algorithm processing V is iteratively used according to statistical nature and reconstructs I, when iterative process terminates The enhanced RGB image I ' of brightness is exported by color space conversion model;
(2) modified R X chromaticity difference diagram C is therefrom extracted by MRXCM methodm', to Cm' execution imagethresholding obtains Cm", and C is handled using mathematical Morphology Algorithmm" therefrom extracts potential mature or immature fruit region Of
(3) the chrominance component H ' for extracting I ', measures the positional relationship of local neighborhood pixel and the centre of neighbourhood, and it is adjacent to measure part The hue information difference of domain pixel and the centre of neighbourhood establishes the weight distribution model of local neighborhood centering heart pixel tonal value, leads to It crosses and the centre of neighbourhood pixel by noise pollution is isolated, reconstructs chrominance component H ' in a manner of weighted meanc, to H 'cExecute image threshold Value is divided to obtain Hc" therefrom extracts potential sepia branch region Os
(4) O is extractedsSkeleton Qs', detect Qs' on angle point and extract it is relevant to branch bifurcated attribute key angle point, Utilize O under gravityfAnd Qs' relative position constraint and crucial angle point spatial characteristics, positioning fruit harvesting point distribution Section.
Further, step (1) the weighting three primary colors luminance component V for extracting current RGB image I, specifically, with becoming Amount R, G and B respectively indicate the grey scale pixel value of the red, green and blue Color Channel of I, calculate weighting three primary colors brightness point according to the following formula Measure V:
V=α R+ β G+ γ B
Further, step (1) is described utilizes modified R X chromaticity difference diagram (Modified Red and Green/Blue (X) Chromatic Mapping, MRXCM) method generates modified R X (Red&Green/Blue) chromaticity difference diagram C from Im, specifically, root The red color tone or green hue shown according to fruit region calculates the monochromatic ratio of R and G or R and B as scale factor, and weights Into conventional red green difference figure or reddish blue difference figure, modified chromaticity difference diagram C is generatedm
Further, step (1) is described from CmMiddle extraction part fruit region RoIs (Regions of Interest), The statistical nature for calculating RoIs Luminance Distribution, specifically, to CmIt executes Threshold segmentation and erosion operation obtains bianry image, extract Local fruit region RoIs calculates the average brightness value M of mask images institute overlay area in V as mask imagesRoIs
Further, step (1) is described iteratively uses Retinex algorithm processing V according to statistical nature and reconstructs I exports the enhanced RGB image I ' of brightness by color space conversion model when iterative process is terminated, specifically, extracting more The three primary colors weighted luminance component of a training image counts the average brightness value M in fruit regiontrain, and execute following steps:
S1. judge whether MRoIs≥Mtrain, if so then execute step S2, S3 is thened follow the steps if not;
S2. I as the enhanced RGB image I ' of brightness and is exported into I ';
S3. enhanced luminance component V ' is obtained using Retinex algorithm, passes through RGB/HSI color space conversion model The tone H and color saturation S of current RGB image are extracted, V ' is merged to generate the enhanced RGB image I ' of brightness, extracts again The average M of I 'RoIs' judges whether MRoIs' >=MtrainIf otherwise continuing to execute step S3, if continuing to execute step S4;
S4. I ' is exported.
Preferably, step (2) is described handles C using mathematical Morphology Algorithmm" therefrom extracts potential mature or prematurity Fruit region Of, specifically, successively using the morphological erosion operation based on coarse scale structures member, based on small scale structures member Dilation operation and holes filling handle Cm", using 8- connectivity criteria from treated CmPotential fruit region O is extracted in "f
Further, step (3) positional relationship for measuring local neighborhood pixel and the centre of neighbourhood, specifically, leading Domain center is (xc,yc) m × n neighborhood in, coordinates computed be (xi,yi) ith pixel and centre of neighbourhood distance dis ((xi,yi),(xc,yc)), the positional relationship w of ith pixel and the centre of neighbourhood is obtained according to the following formulapi:
wpi=exp {-λPmax(dis((xi,yi),(xc,yc)))}
In formula, λpFor position amplification coefficient, i=1,2 ..., m × n.
Further, step (3) the hue information difference for measuring local neighborhood pixel and the centre of neighbourhood, specifically, In field, centre coordinate is (xc,yc) m × n neighborhood in, calculate neighborhood in coordinate be (xi,yi) ith pixel tone value hiWith neighborhood tone intermediate value hmDifference diff (hi,hm), and the neighborhood territory pixel tone value standard deviation sigma in addition to central pointc, according to The different information w of following formula calculating ith pixel and the centre of neighbourhoodHi:
In formula, λHFor tone difference amplification coefficient, i=1,2 ..., m × n.
Further, step (3) the weight distribution model for establishing local neighborhood centering heart pixel tonal value, by every From by noise pollution centre of neighbourhood pixel, chrominance component H ' is reconstructed in a manner of weighted meanc, specifically, passing through wpiAnd wHi Point multiplication operation distribution ith pixel weight wciIf centre of neighbourhood tone value hcWith hmDeviation is larger, then field center is arranged Weight be 0, be otherwise provided as 1, calculate the weighted average of each pixel tonal value in neighborhood, the weight as centre of neighbourhood pixel Structure tone value h 'c, the chrominance component H ' reconstructed after all pixels of H ' is traversed based on above-mentioned processc
Preferably, step (3) is described to H 'cIt executes imagethresholding and obtains Hc" therefrom extracts potential sepia Branch region Os, specifically, according to branch hue information distribution setting segmentation threshold in multiple training images, to H 'cExecute image Threshold division obtains Hc", using 8- connectivity criteria from HcPotential branch region O is extracted in "s
Further, step (4) the extraction OsSkeleton Qs', detect Qs' on angle point and extract with branch bifurcated category Property relevant crucial angle point, specifically, thinning algorithm is utilized to extract OsSkeleton Qs', it is extracted using Harris Corner Detection Algorithm Qs' on whole angle points utilize crotch angle point adjacent according to the bifurcated feature between fruit branches different in the case of more fruit adhesions The mode distribution rule and skeleton connectivity of domain pixel judge whether crotch angle point belongs to crucial angle point and extract crucial angle point.
Further, step (4) is described utilizes O under gravityfAnd Qs' relative position constraint and crucial angle point sky Between distribution character, position fruit harvesting point distributed area, specifically, according to fruit position of centre of gravity under gravity lower than its connect Strong connectedness feature between branch, fruit carpopodium and branch calculates carpopodium and branch join domain ArMiddle all pixels space is sat Target statistical nature, and combine the statistical nature of crucial angular coordinate extract only with OfBranch skeleton with connectivity extracts Harvesting central point of the crucial angle point as fruit on the skeleton far from carpopodium, with ArMiddle pixel and angled key space of points column coordinate Dispersion degree as deviate harvesting point regional standard it is poor, according to harvesting central point and regional standard difference position fruit harvesting point Distributed area.
Compared with prior art, the beneficial effect of technical solution of the present invention is: (1) iterative Retinex algorithm can be automatic The overall brightness distribution that input RGB image is adjusted according to the light characteristic in litchi fruits region, is improving image overall brightness The color information for remaining to maintain each region of original image when distribution, has preferable scene adaptive, is suitable for natural environment Under image preprocessing;(2) simultaneously using in the positional relationship of local neighborhood pixel and hue information reconstruct HSI color space Chrominance component can not only eliminate noise jamming, moreover it is possible to restore the practical hue information of centre of neighbourhood pixel to greatest extent, favorably In the reliability for improving branch extracted region;(3) it is distributed based on Harris Corner Detection Algorithm and the mode of angle point neighborhood territory pixel Rule Extraction key angle point, is avoided that the interference of noise angle point to a certain extent, be conducive to improve litchi fruits harvesting point or Harvest the positional accuracy in region.
Detailed description of the invention
Fig. 1 is the implementation example figure of the fruit harvesting region automatic positioning method process towards natural scene in the present embodiment.
Fig. 2 a is the image embodiment figure of a secondary illumination abundance.
Fig. 2 b is the adaption brightness reinforcing effect implementation example figure of image shown in Fig. 2 a.
Fig. 2 c is the weaker image embodiment figure of a secondary illumination.
Fig. 2 d is the adaption brightness reinforcing effect implementation example figure of image shown in Fig. 2 c.
Fig. 3 a is the litchi fruits extraction effect implementation example figure of image shown in Fig. 2 a.
Fig. 3 b is the litchi fruits extraction effect implementation example figure of image shown in Fig. 2 c.
Fig. 4 a be the centre of neighbourhood not by noise pollution when tone value reconstruction result implementation example figure.
Fig. 4 b be the centre of neighbourhood by noise pollution when tone value reconstruction result implementation example figure.
Fig. 5 a is the lichee branch extraction effect implementation example figure of image shown in Fig. 2 a.
Fig. 5 b is the lichee branch extraction effect implementation example figure of image shown in Fig. 2 c.
Fig. 6 a is that the litchi fruits of image shown in Fig. 2 a harvest point location effect example figure.
Fig. 6 b is that the litchi fruits of image shown in Fig. 2 c harvest point location effect example figure.
Specific embodiment
The attached figures are only used for illustrative purposes and cannot be understood as limitating the patent;
In order to better illustrate this embodiment, the certain components of attached drawing have omission, zoom in or out, and do not represent actual product Size;
To those skilled in the art, it is to be understood that certain known features and its explanation, which may be omitted, in attached drawing 's.
In the description of the present invention, unless otherwise indicated, the meaning of " plurality " is two or more.
The following further describes the technical solution of the present invention with reference to the accompanying drawings and examples.
Embodiment
As shown in Figure 1, a kind of fruit harvesting region automatic positioning method towards natural scene, comprising the following steps:
(1) the weighting three primary colors luminance component V for extracting current RGB image I, utilizes modified R X chromaticity difference diagram (Modified Red and Green/Blue (X) Chromatic Mapping, MRXCM) method generates modified R X (Red&Green/ from I Blue) chromaticity difference diagram Cm, from CmMiddle extraction part fruit region RoIs (Regions of Interest) calculates RoIs Luminance Distribution Statistical nature, according to statistical nature export the enhanced RGB image I ' of brightness;
(2) modified R X chromaticity difference diagram C is therefrom extracted by MRXCM methodm', to Cm' execution imagethresholding obtains Cm", and C is handled using mathematical Morphology Algorithmm" therefrom extracts potential mature or immature fruit region Of
(3) the chrominance component H ' for extracting I ', measures the positional relationship of local neighborhood pixel and the centre of neighbourhood, and it is adjacent to measure part The hue information difference of domain pixel and the centre of neighbourhood establishes the weight distribution model of local neighborhood centering heart pixel tonal value, leads to It crosses and the centre of neighbourhood pixel by noise pollution is isolated, reconstructs chrominance component H ' in a manner of weighted meanc, to H 'cExecute image threshold Value segmentation, therefrom extracts potential sepia branch region Os
(4) O is extractedsSkeleton Qs', detect Qs' on angle point and extract it is relevant to branch bifurcated attribute key angle point, Utilize O under gravityfAnd Qs' relative position constraint and crucial angle point spatial characteristics, positioning fruit harvesting point distribution Section.
The imaging effect in fruit region is easy to be influenced by illumination condition in visual pattern, it is therefore necessary to examine in fruit The illumination compensation surveyed and first carry out image before harvesting point location, and the hue information in fruit region cannot occur significantly to change after compensating Become, and and brightness value higher input picture uniform for luminance information, is not then considered as illumination compensation, otherwise will appear " mistake Degree exposure " phenomenon and cause significantly changing for the original hue information in fruit region.For this purpose, the present invention passes through iterative Retinex Algorithm, it is automatic to enhance according to the Luminance Distribution feature in fruit region in input image lightness information and illumination abundance/homogeneous image The brightness of input picture.
By taking litchi fruits as an example.
When algorithm starts, if current RGB image I is input RGB image Ic.When compensating the luminance information of I, in order to the greatest extent may be used The original hue information of image can not be changed, the weighting three primary colors luminance component V of I is extracted according to formula (1).
V=α R+ β G+ γ B
Wherein, R, G and B respectively indicate the grey scale pixel value of the red, green and blue Color Channel of I, and s.t. indicates constraint condition. Using red color tone litchi fruits region detection as target in the present embodiment, and three parameters being arranged in formula (1) be respectively α= 0.6, β=0.3, γ=0.1, to protrude the grayscale information of red component in image.
In order to isolate the background area different from fruit hue information, setting red component (R) and green (G) from I Or the ratio of blue component (B), as impact factor, the factor value is higher, illustrates the difference between fruit and other background areas It is different bigger, and be weighted in conventional color difference drawing method, obtain the calculating of the modified R X chromaticity difference diagram as shown in formula (2)~(4) Model extracts chromaticity difference diagram C from Im
Cm=λ × R-X (2)
λ=R/X (3)
In order to extract red color tone litchi fruits region, β > γ is set in the present embodiment.
C is divided using Otsu algorithmmTo obtain corresponding bianry imageIn order to guarantee that the region of subsequent extracted is Litchi fruits part is corroded by the circular configuration member that radius is more than 8 pixels in the present embodimentIt is secondary corresponding to obtain one The mask images in fruit region, the luminance picture in litchi fruits region is extracted by the point multiplication operation of mask images and V, and is calculated The average value M of the luminance pictureRoIs.On the other hand, it is manually chosen from the training image data comprising red color tone litchi fruits Fruit region, and calculate the weighting three primary colors luminance component and average brightness value M in these regionstrain
Compare MRoIsAnd Mtrain:
If MRoIs≥Mtrain, then not executing the brightness based on Retinex algorithm to V enhances, directly output I '=Ic
If MRoIs< Mtrain, then executing the brightness based on Retinex algorithm to V enhances, and obtains new luminance component V ', passes through RGB/HSI color space conversion model extraction IcChrominance component H and color saturation component S, and merge V ' generation brightness enhancing RGB image I ' afterwards, enables I againc=I ' continues according to above-mentioned workflow management IcMRoIs, enhance I in an iterative mannercIt is bright Degree, until meeting condition MRoIs≥MtrainWhen, export the enhanced RGB image I ' of brightness.
Fig. 2 a~Fig. 2 d gives with above-mentioned iterative manner using the effect contrast figure of Retinex algorithm before and after the processing.Figure 2a is the image of a secondary illumination abundance, and brightness reinforcing effect is as shown in Figure 2 b, and Fig. 2 c is the weaker image of a secondary illumination, bright It is as shown in Figure 2 d to spend reinforcing effect.
By formula (2)~(4) from the middle extraction modified R X chromaticity difference diagram C of I 'm', using Otsu algorithm to Cm' execute thresholding Segmentation obtains bianry image Cm" successively uses the erosion operation based on coarse scale structures member (radius can be used for 4 pixels Circular configuration member), dilation operation based on small scale structures member (radius can be used first for the circular configuration of 3 pixels) and hole Filling processing Cm", by 8- connectivity criteria from treated Cm" in extract potential fruit region, and be labeled as Of.Above-mentioned " big ruler " big " and " small " in very little structural elements ", " small scale structures member " is in processing CmThe erosion operation and dilation operation carried out when " What the structural elements of use were compared.Fig. 3 gives through treated litchi fruits extracted region effect picture, and Fig. 3 a is The litchi fruits extraction effect implementation example figure of image shown in Fig. 2 a, Fig. 3 b are that the litchi fruits extraction effect of image shown in Fig. 2 c is real Apply example diagram.
In order to guarantee the accurate extraction in sepia branch region, the present invention is given birth to again using local hue information restructing algorithm At filtered chrominance component, to eliminate the noise jamming in input picture.By RGB/HSI color space conversion model from I ' Middle extraction chrominance component H '.In any m × n neighborhood of H ', if the coordinate and tone value of the centre of neighbourhood are respectively (xc,yc) and hc, the coordinate and tone value respectively (x of i-th of (i=1,2 ..., m × n) pixeli,yi) and hi, i-th is determined according to formula (5) A pixel (xi,yi) with the positional relationship w of the centre of neighbourhoodpi
wpi=exp {-λpmax(dis((xi,yi),(xc,yc)))},(xi,yi)≠(xc,yc) (5)
Wherein, λpFor position amplification coefficient, λ is taken in the present embodimentp=2;dis((xi,yi),(xc,yc)) it is metric point (xi,yi) and (xc,yc) the distance between function namely ith pixel taken in the present embodiment at a distance from the centre of neighbourhood chessboard away from From i.e. dis ((xi,yi),(xc,yc))=max (| xi-xc|,|yi-yc|)。
In addition, another key factor for influencing the estimation of m × n centre of neighbourhood hue information is the tone value of neighborhood territory pixel, it is Reduce influence of the centre of neighbourhood polluted by noise to its hue information reconstruction result, the present invention, which measures, removes center in neighborhood Pixel tone standard deviation sigma outside pointcAnd calculating field intermediate value hm, local neighborhood pixel (x is measured by formula (6) and (7)i,yi) With hmDifference on hue information, result queue wHi
Wherein, λHFor tone difference amplification coefficient, λ is taken in the present embodimentH=1;diff(hi,hc) be ith pixel color Tone pitch hiWith the difference of neighborhood tone intermediate value hm, diff (h is taken in the present embodimenti,hc)=| | hi-hc||2, NcFor except point (xc,yc) Outer neighborhood territory pixel set.
Since the tone value of centre of neighbourhood pixel can be influenced by the position of m × n neighborhood territory pixel and tone value simultaneously, this It invents while considering wpiAnd wHiCarry out reconstruction point (xc,yc) hue information, allow it closer to practical tone value, adopted in the present embodiment Neighborhood territory pixel (x is formed with the mode of dot producti,yi) weight, i.e. wci=wpi×wHi.Particularly, point (xc,yc) before reconstitution Tone may be interfered by noise, so for (xi,yi)=(xc,yc) situation, if hcWith hmDeviation is larger, then w is arrangedci =0, otherwise w is setci=1.Finally the weighted mean of m × n neighborhood hue information is calculated as point (x according to formula (8)c,yc) Reconstruction result.
After whole pixels to H ' complete above-mentioned calculating, the reconstructed image H ' of H ' can be obtainedc.Fig. 4 gives m × n The centre of neighbourhood pixel tonal value reconstruct numerical operation result figure, Fig. 4 a be centre of neighbourhood pixel not by noise pollution when tone Be worth reconstruction result, Fig. 4 b be centre of neighbourhood pixel by noise pollution when tone value reconstruction result, take m=5 in the present embodiment, N=5.Each grid in Fig. 4 a and Fig. 4 b represents a pixel, and the first row numerical value in grid indicates the point before reconstitution Tone value, the numerical value in the second row bracket indicates contribution weight of the hue information of the point in restructuring procedure, neighborhood midpoint In the third line numerical value indicate the tone value of point after reconstitution.
Litchi branch strip area is manually extracted from training image data, and counts these areas after being transformed into HSI color space The average tone value h in domainavg, as to H 'cCarry out the segmentation threshold of binary conversion treatment, H 'cMiddle tone value is less than or equal to havgPicture Element is set to prospect, is otherwise set to background, and potential branch region O is extracted in the foreground image obtained by as 8- connectivity criterias。 Fig. 5 gives the effect picture of litchi branch strip area extraction, and Fig. 5 a is the lichee branch extraction effect embodiment of image shown in Fig. 2 a Figure, Fig. 5 b are the lichee branch extraction effect implementation example figure of image shown in Fig. 2 c.
O is handled using thinning algorithms, extract the skeleton O of litchi branch strip areas', O is detected by Harris algorithms' in All angle points (set its quantity as k).In order to judge whether certain angle point is located at branch bifurcation, all angle points are traversed, for jth (j=1,2 ..., k) a angle point, if its neighborhood territory pixel meets mode distribution rule shown in formula (9) simultaneously, by angle point j Coordinate be added to angled key point set AcIn, otherwise delete angle point j.
Wherein, N8(Pi) indicate that 8 neighborhoods of angle point j (do not include the pixel quantity that value is 1 in angle point j), P2、P4、P6With P8For the 4 neighborhood territory pixel values of angle point j, and they are located at top, right, lower section and the left of angle point j.
To OfMorphological dilations operation (radius can be used for the circular configuration of 3 pixels member) is executed, O is obtainedf', by Os′ With Of' region superposition is carried out, therefrom search for the join domain A of litchi fruits and branchr, and calculate ArMiddle all pixels point row is sat Target mean value Pr1With the mean value P of column coordinater2.Then according to the opposite position of litchi fruits under gravity and litchi branch strip area It sets and adhesion relation, calculates AcThe mean value P of middle key angle point row coordinatec1With the mean value P of column coordinatec2If AcFor empty set or Pr1 < Pc1, from Os' middle rejecting and Of' do not have connectivity branch region, extract only with OfBranch skeleton with connectivity.Most Afterwards, from AcThe middle the smallest angle point of search row coordinate value, and centered on the angle point, with Pr2With Pc2Between absolute difference be standard Difference determines the harvesting point distributed area of litchi fruits.Fig. 6 a, Fig. 6 b give the effect picture of litchi fruits harvesting point location, figure 6a is that the litchi fruits of image shown in Fig. 2 a harvest point location effect example figure, and Fig. 6 b is the litchi fruits of image shown in Fig. 2 c Harvest point location effect example figure.
The same or similar label correspond to the same or similar components;
Positional relationship is described in attached drawing only for illustration, should not be understood as the limitation to this patent;
Obviously, the above embodiment of the present invention be only to clearly illustrate example of the present invention, and not be pair The restriction of embodiments of the present invention.For those of ordinary skill in the art, may be used also on the basis of the above description To make other variations or changes in different ways.There is no necessity and possibility to exhaust all the enbodiments.It is all this Made any modifications, equivalent replacements, and improvements etc., should be included in the claims in the present invention within the spirit and principle of invention Protection scope within.

Claims (10)

1. a kind of fruit harvesting region automatic positioning method towards natural scene, which comprises the following steps:
(1) the weighting three primary colors luminance component V for extracting current RGB image I, utilizes modified R X chromaticity difference diagram (Modified Red And Green/Blue (X) Chromatic Mapping, MRXCM) method generates modified R X (Red&Green/Blue) from I Chromaticity difference diagram Cm, from CmMiddle extraction part fruit region RoIs (Regions of Interest) calculates the system of RoIs Luminance Distribution Feature is counted, Retinex algorithm processing V is iteratively used according to statistical nature and reconstructs I, is passed through when iterative process terminates Color space conversion model exports the enhanced RGB image I ' of brightness;
(2) modified R X chromaticity difference diagram C is therefrom extracted by MRXCM methodm', to Cm' execution imagethresholding obtains Cm", and C is handled using mathematical Morphology Algorithmm", from CmPotential mature or immature fruit region O is extracted in "f
(3) the chrominance component H ' for extracting I ', measures the positional relationship of local neighborhood pixel and the centre of neighbourhood, measures local neighborhood picture Element and the hue information difference of the centre of neighbourhood, establish the weight distribution model of local neighborhood centering heart pixel tonal value, by every From by noise pollution centre of neighbourhood pixel, chrominance component H is reconstructed in a manner of weighted meanc', to Hc' execute image threshold Segmentation obtains Hc" therefrom extracts potential sepia branch region Os
(4) O is extractedsSkeleton Qs', detect Qs' on angle point and extract crucial angle point relevant to branch bifurcated attribute, utilization O under gravityfAnd Qs' relative position constraint and crucial angle point spatial characteristics, position fruit harvesting point distributed area Between.
2. the fruit harvesting region automatic positioning method according to claim 1 towards natural scene, which is characterized in that step Suddenly (1) the weighting three primary colors luminance component V for extracting current RGB image I, specifically, respectively indicating I's with variable R, G and B The grey scale pixel value of red, green and blue Color Channel calculates weighting three primary colors luminance component V according to the following formula:
V=α R+ β G+ γ B
3. the fruit harvesting region automatic positioning method according to claim 1 towards natural scene, which is characterized in that step Suddenly (1) it is described using modified R X chromaticity difference diagram (Modified Red and Green/Blue (X) Chromatic Mapping, MRXCM) method generates modified R X (Red&Green/Blue) chromaticity difference diagram C from Im, specifically, shown according to fruit region Red color tone or green hue calculate the monochromatic ratio of R and G or R and B as scale factor, and are weighted to conventional red green difference figure Or in reddish blue difference figure, modified chromaticity difference diagram C is generatedm
4. the fruit harvesting region automatic positioning method according to claim 1 towards natural scene, which is characterized in that step Suddenly (1) is described from CmMiddle extraction part fruit region RoIs (Regions of Interest) calculates the system of RoIs Luminance Distribution Feature is counted, specifically, to CmIt executes Threshold segmentation and erosion operation obtains bianry image, extract local fruit region RoIs conduct Mask images, and calculate the average brightness value M of mask images institute overlay area in VRoIs
5. the fruit harvesting region automatic positioning method according to claim 4 towards natural scene, which is characterized in that step Suddenly (1) is described iteratively uses Retinex algorithm processing V according to statistical nature and reconstructs I, logical when iterative process terminates The color space conversion model output enhanced RGB image I ' of brightness is crossed, specifically, the three primary colors for extracting multiple training images add Luminance component is weighed, the average brightness value M in fruit region is countedtrain, and execute following steps:
S1. judge whether MRoIs≥Mtrain, if so then execute step S2, S3 is thened follow the steps if not;
S2. I as the enhanced RGB image I ' of brightness and is exported into I ';
S3. enhanced luminance component V ' is obtained using Retinex algorithm, passes through RGB/HSI color space conversion model extraction The tone H and color saturation S of current RGB image merge V ' to generate the enhanced RGB image I ' of brightness, extract I's ' again Average MRoIs' judges whether MRoIs' >=MtrainIf otherwise continuing to execute step S3, if continuing to execute step S4;
S4. I ' is exported.
6. the fruit harvesting region automatic positioning method according to claim 1 towards natural scene, which is characterized in that step Suddenly (3) positional relationship for measuring local neighborhood pixel and the centre of neighbourhood, specifically, being (x at field centerc,yc) m × n In neighborhood, coordinates computed is (xi,yi) ith pixel and centre of neighbourhood distance dis ((xi,yi),(xc,yc)), under Formula obtains the positional relationship w of ith pixel and the centre of neighbourhoodpi:
wpi=exp {-λPmax(dis((xi,yi),(xc,yc)))}
In formula, λpFor position amplification coefficient, i=1,2 ..., m × n.
7. the fruit harvesting region automatic positioning method according to claim 1 or 6 towards natural scene, feature exist In step (3) the hue information difference for measuring local neighborhood pixel and the centre of neighbourhood, specifically, in field centre coordinate For (xc,yc) m × n neighborhood in, calculate neighborhood in coordinate be (xi,yi) ith pixel tone value hiIn neighborhood tone Value hmDifference diff (hi,hm), and the neighborhood territory pixel tone value standard deviation sigma in addition to central pointc, calculate according to the following formula i-th The different information w of pixel and the centre of neighbourhoodHi:
(xi,yi)≠(xc,yc)
In formula, λHFor tone difference amplification coefficient, i=1,2 ..., m × n.
8. the fruit harvesting region automatic positioning method according to claim 7 towards natural scene, which is characterized in that step Suddenly (3) the weight distribution model for establishing local neighborhood centering heart pixel tonal value, by the way that the neighborhood by noise pollution is isolated Center pixel reconstructs chrominance component H ' in a manner of weighted meanc, specifically, passing through wpiAnd wHiPoint multiplication operation distribute i-th The weight w of pixelciIf centre of neighbourhood tone value hcWith hmDeviation is larger, then the weight that field center is arranged is 0, is otherwise arranged It is 1, calculates the weighted average of each pixel tonal value in neighborhood, the reconstruct tone value h ' as centre of neighbourhood pixelc, based on upper State the chrominance component H ' reconstructed after all pixels of process traversal H 'c
9. the fruit harvesting region automatic positioning method according to claim 1 towards natural scene, which is characterized in that step Suddenly (4) the extraction OsSkeleton Qs', detect Qs' on angle point and extract crucial angle point relevant to branch bifurcated attribute, have Body is to extract O using thinning algorithmsSkeleton Qs', Q is extracted using Harris Corner Detection Algorithms' on whole angle points, root According to the bifurcated feature between fruit branches different in the case of more fruit adhesions, rule are distributed using the mode of crotch angle point neighborhood territory pixel Then judge whether crotch angle point belongs to crucial angle point and extract crucial angle point with skeleton connectivity.
10. the fruit harvesting region automatic positioning method according to claim 1 towards natural scene, which is characterized in that Step (4) is described to utilize O under gravityfAnd Qs' relative position constraint and crucial angle point spatial characteristics, position fruit Real harvesting point distributed area, specifically, connecting branch, fruit carpopodium and branch lower than it according to fruit position of centre of gravity under gravity Strong connectedness feature between item calculates carpopodium and branch join domain ArThe statistical nature of middle all pixels space coordinate, and tie Close crucial angular coordinate statistical nature extract only with OfBranch skeleton with connectivity extracts separate carpopodium on the skeleton Harvesting central point of the crucial angle point as fruit, with ArMiddle pixel and the dispersion degree of angled key space of points column coordinate are as deviation The regional standard for harvesting point is poor, positions fruit harvesting point distributed area according to harvesting central point and regional standard difference.
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