CN106248634A - Fruit exocuticle glossiness measurement apparatus and method - Google Patents

Abstract

The invention provides a kind of fruit exocuticle glossiness measurement apparatus and method, including casing, industrial camera, light source, power module and industrial computer；Wherein, described industrial camera is arranged on upper side in casing, and described industrial camera is used for collecting fruit coloured image；Described light source is arranged on the medial angle end of described casing, for providing uniform source of light for casing so that fruit overall brightness is uniform；For the coloured image obtained, extract its luminance component and carry out glossiness analysis, result is compared with the glossiness on-gauge plate using vancometer to record gloss value simultaneously, compare the numerical value of fruit surface glossiness.Present invention employs contactless design, glossiness can be measured by simple camera image, solve tradition vancometer and be difficult to measure the problem of non-smooth surface, have preferable degree of accuracy and measure efficiency.

Description

Device and method for measuring glossiness of outer surface of fruit

Technical Field

The invention relates to an optical detection device, in particular to a device and a method for measuring the glossiness of the outer surface of a fruit.

Background

China is a big agricultural country, the agricultural problem is always an important problem in the social development of China, and many past research works are limited by the fact that technical short boards cannot be developed. In the 21 st century, with the development of science and technology, agricultural research is gradually combined with various disciplines such as machinery, electronic information, artificial intelligence and the like, and many problems which are difficult to solve have new solutions.

The gloss of the outer skin of a fruit has in the past been a very difficult parameter to measure, and researchers often visually assess the gloss of a fruit through personal experience while grading the gloss of the fruit. The measurement mode depends on personal subjective judgment, and results obtained by different measuring personnel are often different, so that measurement errors are generated, and the quality control of enterprises is not facilitated. Meanwhile, the manual mode is easy to cause fatigue, is not suitable for large-scale glossiness measurement, is not beneficial to large-scale fruit classification of enterprises, and increases the production cost of the enterprises. It is therefore important to obtain standardized measurements using a computer while improving the gloss measurement efficiency.

Currently, China lacks relevant standards for fruit glossiness, such as fruit glossiness measurement. Zhongbing Yu et al, university of northeast agriculture, peels the outer skin of the fruit and lays it flat, and the gloss value of the fruit is measured by using a professional gloss meter HYD-09. However, the method has complicated operation steps, and the fruits need to be cut to have relatively uniform thickness so that the outer skins of the fruits are smooth to obtain relatively accurate gloss values, so that the difference of the gloss values of the fruits of the same variety is relatively large, and the fruits are damaged by cutting the outer skins at the same time, which belongs to destructive measurement and is not beneficial to large-scale measurement and can only be used for comparison among the fruits of different varieties.

In the aspect of machine vision, the on-line automatic pearl color glossiness grading device based on monocular multi-view machine vision of Thjiang industry university et al can realize non-contact glossiness measurement of objects by using images, but the device also needs a large amount of sorting experience and a large amount of data to obtain a proper experience coefficient, and meanwhile, the multi-view device is complex and high in cost, and is not suitable for glossiness measurement of the outer skin of fruits considering that the fruits are different from the pearls and do not need too accurate glossiness values.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a device and a method for measuring the gloss of the outer surface of a fruit.

The device for measuring the glossiness of the outer surface of the fruit comprises a box body, an industrial camera, a light source, a power supply module and an industrial personal computer;

the industrial camera is arranged on the upper side face in the box body and is used for collecting fruit color images;

the light source is arranged at the inner corner end of the box body and used for providing a uniform light source for the box body, so that the overall brightness of the fruit is uniform;

the power supply module is electrically connected with the light source and is used for providing power for the light source;

the industrial personal computer and the industrial camera; the industrial personal computer is used for controlling the industrial camera to acquire images and analyze the glossiness.

According to another aspect of the present invention, there is provided a method for measuring the gloss of the outer skin of a fruit, comprising the steps of:

step S1: measuring and recording the glossiness value of the glossiness standard plate by using a glossiness meter;

step S2: putting the detected fruit and the glossiness standard plate into a box body, and adjusting the aperture and the focal length of an industrial camera to enable the image of the detected fruit to be clear;

step S3: collecting the image of the detected fruit and storing the image of the detected fruit to an industrial personal computer for image processing;

step S4: segmenting a fruit light reflecting area in the image based on the HIS model and calculating a light reflecting intensity value;

step S5: finding out the image of the gloss standard plate from the cucumber image, calculating the light reflection intensity value of the standard plate according to the step S3, obtaining a gloss calibration matrix, and calibrating the gloss of the fruit.

Preferably, the gloss value calculating step is:

step S41: and taking the H component of the HIS model of the image of the detected fruit, and extracting the cross section outline of the fruit through threshold segmentation.

Step S42: the obtained fruit cross section outline is corroded to reduce the area of the fruit cross section outline so as to reduce the fruit

Influence of the brightness of the boundary of the real section outline on the glossiness, and the foreground and the back of the matrix after the binarization of the fruit section outline

Turning the scene to enable the gray value of the background to be 1 and the gray value of the foreground to be 0;

step S43: extracting a fruit image HIS model I component diagram, and performing matrix subtraction with the contour diagram obtained in the step S42 to obtain a fruit image I component with the background removed;

step S44: performing threshold segmentation on the extracted fruit image I component to segment a fruit light reflecting area, and finding the original gray value of the fruit light reflecting area in the original image of the I component;

step S45: and calculating the light reflection intensity value of the fruit in unit area.

Preferably, the HIS model reconversion formula is:

$H=\left\{\begin{array}{cc}\mathrm{\θ},& B\≤G\\ 360-\mathrm{\θ},& B>G\end{array}\right.$

$S=1-\frac{3}{(R+G+B)}\[\min (R,G,B)\]$

$I=\frac{1}{3}(R+G+B)$

wherein,

wherein R, G, B represents the red, green and blue values of the RGB color space, respectively; s is the saturation, theta is the angle of the color in the HIS model,

the S and I components have been normalized to 0 to 1, and the H component divided by 2 π can be normalized to 0 to 1.

Preferably, the fruit reflected light intensity value per unit area is calculated according to the following formula:

$I_c=\frac{S_m}{S_m+S_d}\underset{i=0}{\overset{m}{\Σ}}{I}_m\left(i\right)$

in the formula, S_mThe area of a light reflecting area in the fruit image is shown; s_dThe area of a non-light-reflecting area in the fruit image; i is_m(i) -the I-component gray value at the pixel point of the retroreflective area; i is_cObtaining a fruit reflection strength value for a computer; m represents a certain pixel point in the region.

Preferably, I_cReflection strength value I of standard gloss board_sComparison according to the formulaObtaining an actual gloss value;

wherein G is_c、G_sThe actual glossiness of the tested fruit and the actual glossiness of the standard glossiness plate are respectively.

Compared with the prior art, the invention has the following beneficial effects:

1. the box body can reduce the influence of ambient light, so that the ambient parameters measured each time are close to each other, and the obtained results are more uniform;

2. the industrial camera is a monocular vision system, and the image processing speed is high;

3. the actual glossiness of the fruits is determined by comparing the actual glossiness with the glossiness standard plate, and the glossiness result is more accurate;

4. the invention belongs to non-contact measurement, and has high efficiency, high precision and wide application prospect.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a schematic view showing the structure of a device for measuring the gloss of the outer surface of a fruit according to the present invention;

FIG. 2 is a flow chart of the method for measuring the gloss of the outer skin of a fruit according to the present invention;

FIG. 3 is a graph of the I component of a fruit image collected in the present invention;

FIG. 4 is a graph of the fruit profile obtained by the H component of the present invention;

FIG. 5 is a graph of the I fraction of fruit after background removal in accordance with the present invention;

fig. 6 shows the light reflection region found by threshold value division in the present invention.

In the figure: 1 is the box, 2 is the industrial camera, 3 is power module, 4 is the industrial computer, and 5 is white LED fluorescent tube.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.

In this embodiment, the device for measuring the glossiness of the outer surface of the fruit, provided by the invention, comprises a box body, an industrial camera, a light source, a power module and an industrial personal computer;

the industrial camera is arranged on the upper side face in the box body and is used for collecting fruit color images;

the light source is arranged at the inner corner end of the box body and used for providing a uniform light source for the box body, so that the overall brightness of the fruit is uniform;

the power supply module is electrically connected with the light source and is used for providing power for the light source;

the industrial personal computer and the industrial camera; the industrial personal computer is used for controlling the industrial camera to acquire images and analyze the glossiness.

The camera and the lens of the industrial camera need to be calibrated before the image is acquired; according to the Zhangyingyou calibration method, images of the camera calibration plate at different angles are shot, and the internal parameters of the camera, the distortion of a lens, the magnification and the focal length are calculated.

The invention provides a method for measuring the glossiness of the outer surface of a fruit, which comprises the following steps:

step S1: measuring and recording the glossiness value of the glossiness standard plate by using a glossiness meter;

step S2: putting the detected fruit and the glossiness standard plate into a box body, and adjusting the aperture and the focal length of an industrial camera to enable the image of the detected fruit to be clear;

step S3: collecting the image of the detected fruit and storing the image of the detected fruit to an industrial personal computer for image processing;

step S4: segmenting a fruit light reflecting area in the image based on the HIS model and calculating a light reflecting intensity value;

step S5: finding out the image of the gloss standard plate from the cucumber image, calculating the light reflection intensity value of the standard plate according to the step S3, obtaining a gloss calibration matrix, and calibrating the gloss of the fruit.

The glossiness standard plate is divided into three types which are respectively H-type high glossiness plates; a M-type medium gloss plate; l-type low gloss board.

The gloss value calculation step is as follows:

step S41: and taking the H component of the HIS model of the image of the detected fruit, and extracting the cross section outline of the fruit through threshold segmentation.

Step S42: the obtained fruit cross section outline is corroded to reduce the area of the fruit cross section outline so as to reduce the fruit

Influence of the brightness of the boundary of the real section outline on the glossiness, and the foreground and the back of the matrix after the binarization of the fruit section outline

Turning the scene to enable the gray value of the background to be 1 and the gray value of the foreground to be 0;

step S43: extracting a fruit image HIS model I component diagram, and performing matrix subtraction with the contour diagram obtained in the step S42 to obtain a fruit image I component with the background removed;

step S44: performing threshold segmentation on the extracted fruit image I component to segment a fruit light reflecting area, and finding the original gray value of the fruit light reflecting area in the original image of the I component;

step S45: and calculating the light reflection intensity value of the fruit in unit area.

The HIS model reconversion formula is as follows:

$H=\left\{\begin{array}{cc}\mathrm{\θ},& B\≤G\\ 360-\mathrm{\θ},& B>G\end{array}\right.$

$S=1-\frac{3}{(R+G+B)}\[\min (R,G,B)\]$

$I=\frac{1}{3}(R+G+B)$

wherein,

wherein R, G, B represents the red, green and blue values of the RGB color space, respectively; s is the saturation, theta is the angle of the color in the HIS model,

the S and I components have been normalized to 0 to 1, and the H component divided by 2 π can be normalized to 0 to 1.

The fruit light reflection intensity value in the unit area is calculated according to the following formula:

$I_c=\frac{S_m}{S_m+S_d}\underset{i=0}{\overset{m}{\Σ}}{I}_m\left(i\right)$

in the formula, S_mThe area of a light reflecting area in the fruit image is shown; s_dThe area of a non-light-reflecting area in the fruit image; i is_m(i) -the I-component gray value at the pixel point of the retroreflective area; i is_cObtaining a fruit reflection strength value for a computer; m represents a certain pixel point in the region.

Will I_cReflection strength value I of standard gloss board_sComparison according to the formulaObtaining an actual gloss value;

wherein G is_c、G_sThe actual glossiness of the tested fruit and the actual glossiness of the standard glossiness plate are respectively.

The device and the method for measuring the gloss of the outer surface of the fruit provided by the embodiment aim to realize the non-contact measurement of the gloss of the outer surface of the fruit by a monocular vision technology so as to obtain a standardized and uniform gloss value. The fruit to be measured is placed in the experiment box and covered with the curtain, so that the influence of ambient light on measurement can be effectively removed, the measurement error between each measurement is reduced, and the white background is convenient for distinguishing the target object from the background. And analyzing based on an image HIS model in the image processing process, extracting a fruit contour binary matrix by using the H component image, and finding out pixel points belonging to the fruit from the I component image by using the contour binary matrix. And then according to the property that the I component represents the image brightness, finding out the area of the fruit reflecting light by a threshold segmentation method, correspondingly calculating the gray value of the pixel point belonging to the light reflecting area, calculating to obtain the glossiness value, and comparing the glossiness value with a glossiness standard plate. The device and the method for measuring the glossiness of the outer surface of the fruit can collect fruit images, obtain the glossiness value and record and store the glossiness value.

The light source arrangement of the invention adopts a uniform illumination mode, four white LED lamp tubes are respectively arranged on the upper left corner, the upper right corner, the lower left corner and the lower right corner of the box body in parallel, and the angles between the four white LED lamp tubes and the measured object are respectively 45 degrees and 0 degree. The fruits are parallel to the lamp tube as much as possible when the strip-shaped fruits are collected, and the influence of a light source on the light received by the fruits is reduced. The arrangement mode of the light source can ensure that the fruits uniformly receive light and the light reflecting area is uniform.

According to the invention, an HIS color model is selected, and the I component of the HIS color model accords with the perception of human eyes on brightness, so that the HIS color model can be used for analyzing glossiness; when the I component background is removed, the I component image cannot be directly subjected to threshold segmentation due to the influence of shadows. Therefore, the contour of the fruit is extracted by using the H component image which is less affected by the shadow, and the area of the contour is slightly reduced by using the corrosion operation to remove the influence of the boundary halo. After the contour binary matrix is subtracted from the I component image, the point with the pixel value larger than 0 can be regarded as the pixel point belongs to the fruit, and then the glossiness measurement is carried out on the basis of the point.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.

Claims (7)

1. A fruit exocuticle glossiness measuring device is characterized by comprising a box body, an industrial camera, a light source, a power supply module and an industrial personal computer;

the industrial camera is arranged on the upper side face in the box body and is used for collecting fruit color images;

the light source is arranged at the inner corner end of the box body and used for providing a uniform light source for the box body, so that the overall brightness of the fruit is uniform;

the power supply module is electrically connected with the light source and is used for providing power for the light source;

the industrial personal computer and the industrial camera; the industrial personal computer is used for controlling the industrial camera to acquire images and analyze the glossiness.

2. The fruit exocuticle gloss measurement device of claim 1, wherein a curtain is provided on one side of the box;

the curtain and the box body enclose a light-tight closed space; and the inner side surface of the curtain is provided with light-tight silver tinfoil.

3. A fruit outer skin gloss measurement method characterized by using the fruit outer skin gloss measurement device according to any one of claims 1 to 3, comprising the steps of:

step S1: measuring and recording the glossiness value of the glossiness standard plate by using a glossiness meter;

step S2: putting the detected fruit and the glossiness standard plate into a box body, and adjusting the aperture and the focal length of an industrial camera to enable the image of the detected fruit to be clear;

step S3: collecting the image of the detected fruit and storing the image of the detected fruit to an industrial personal computer for image processing;

step S4: segmenting a fruit light reflecting area in the image based on the HIS model and calculating a light reflecting intensity value;

step S5: finding out the image of the gloss standard plate from the cucumber image, calculating the light reflection intensity value of the standard plate according to the step S3, obtaining a gloss calibration matrix, and calibrating the gloss of the fruit.

4. The method for measuring the gloss of the outer surface of a fruit according to claim 3, wherein the step of calculating the gloss value is:

step S41: and taking the H component of the HIS model of the image of the detected fruit, and extracting the cross section outline of the fruit through threshold segmentation.

Step S42: carrying out corrosion treatment on the obtained fruit section outline to reduce the area of the fruit section outline so as to reduce the influence of the brightness of the boundary of the fruit section outline on the glossiness, and turning over the foreground and the background of the matrix after the fruit section outline is binarized so that the gray value of the background is 1 and the gray value of the foreground is 0;

step S43: extracting a fruit image HIS model I component diagram, and performing matrix subtraction with the contour diagram obtained in the step S42 to obtain a fruit image I component with the background removed;

step S44: performing threshold segmentation on the extracted fruit image I component to segment a fruit light reflecting area, and finding the original gray value of the fruit light reflecting area in the original image of the I component;

step S45: and calculating the light reflection intensity value of the fruit in unit area.

5. The fruit exocuticle gloss value calculation step according to claim 4, characterized in that said HIS model reconversion formula is:

$H=\left\{\begin{array}{c}\mathrm{\θ},B\≤G\\ 360-\mathrm{\θ},B>G\end{array}\right.$

$S=1-\frac{3}{(R+G+B)}\[\min (R,G,B)\]$

$I=\frac{1}{3}(R+G+B)$

wherein,

wherein R, G, B represents the red, green and blue values of the RGB color space, respectively; s is saturation, theta is the angle of the color in the HIS model,

the S and I components have been normalized to 0 to 1, and the H component divided by 2 π can be normalized to 0 to 1.

6. The fruit exocuticle gloss value calculation step according to claim 4, wherein said fruit reflectance intensity value per unit area is calculated according to the following formula:

$I_c=\frac{S_m}{S_m+S_d}\underset{i=0}{\overset{m}{\Σ}}{I}_m\left(i\right)$

in the formula, S_mThe area of a light reflecting area in the fruit image is shown; s_dThe area of a non-light-reflecting area in the fruit image; i is_m(i) -I component gray at pixel point of the reflective regionA value of the metric; i is_cObtaining a fruit reflection strength value for a computer; m represents a certain pixel point in the region.

7. The method for measuring the gloss of the outer surface of fruit according to claim 4, wherein I is_cReflection strength value I of standard gloss board_sComparison according to the formulaObtaining an actual gloss value;

wherein G is_c、G_sThe actual glossiness of the tested fruit and the actual glossiness of the standard glossiness plate are respectively.