Diamond cleanliness measurement method and system
阅读说明：本技术 钻石净度测量方法和系统 (Diamond cleanliness measurement method and system ) 是由 郑家荣 黄健荣 陈江 程娟 邓咏芝 许冠中 于 2018-12-28 设计创作，主要内容包括：一种能使用计算机化系统(300)操作的方法,所述计算机化系统(300)用于根据钻石(315、400)的本体内的内部缺陷来对钻石(315、400)的净度分级,所述计算机化系统(300)包括能操作地互连在一起的光学图像获取装置(310)、处理器模块(320)以及输出模块(340),所述方法包括以下步骤：(i)经由光学图像获取装置(310)获取具有用所述钻石(315、400)的折射率校正的不同聚焦深度的钻石(315、400)的多个俯视图图像,其中,焦点深度由所述钻石(315、400)的高度确定,并且在具有预定的恒定光水平的环境中获取所述多个俯视图图像,并且其中,将所述俯视图定义为垂直于所述钻石(315、400)的台面(410)的视图,并且将所述钻石(315、400)的所述高度定义为垂直于所述钻石(315、400)的所述台面(410)并且穿过所述钻石(315、400)的亭部的顶点的中心轴的长度；(ii)在处理器模块(320)中,检测所述钻石(315、400)的本体内的缺陷,其中,从与所述多个俯视图图像中的每个获取到的图像中的相邻像素相比的像素亮度水平的对比变化中检测所述缺陷；根据所述钻石(315、400)的本体内的所述缺陷的几何形状、大小以及位置向每个检测到的缺陷施加惩罚分数；并且基于所述惩罚分数的函数来分配净度分级；以及(iii)从输出模块(340)提供指示在(ii)中分配的所述净度分级的信号。(A method operable using a computerized system (300), the computerized system (300) for grading the clarity of a diamond (315, 400) according to internal imperfections within the body of the diamond (315, 400), the computerized system (300) comprising an optical image acquisition device (310), a processor module (320) and an output module (340) operatively interconnected together, the method comprising the steps of: (i) acquiring, via an optical image acquisition device (310), a plurality of top view images of a diamond (315, 400) having different depths of focus corrected by the refractive index of the diamond (315, 400), wherein the depth of focus is determined by the height of the diamond (315, 400) and the plurality of top view images are acquired in an environment having a predetermined constant light level, and wherein the top view is defined as a view perpendicular to a table (410) of the diamond (315, 400) and the height of the diamond (315, 400) is defined as a length perpendicular to the table (410) of the diamond (315, 400) and passing through a central axis of a vertex of a pavilion of the diamond (315, 400); (ii) detecting, in a processor module (320), a defect within the body of the diamond (315, 400), wherein the defect is detected from a contrast change in pixel brightness levels compared to adjacent pixels in images acquired for each of the plurality of top view images; applying a penalty score to each detected defect according to the geometry, size and location of said defect within the body of said diamond (315, 400); and assigning a net rating based on a function of the penalty score; and (iii) providing a signal from an output module (340) indicative of the clarity grade assigned in (ii).)
1. A method operable using a computerized system for grading the clarity of a diamond according to internal imperfections within the body of the diamond, the computerized system comprising an optical image acquisition device, a processor module and an output module operatively interconnected together, the method comprising the steps of:
(i) acquiring, via an optical image acquisition device, a plurality of top view images of the diamond having different depths of focus corrected by the refractive index of the diamond, wherein the depth of focus is determined by the height of the diamond and the plurality of top view images are acquired in an environment having a predetermined constant light level, and wherein the top view is defined as a view perpendicular to a table of the diamond and the height of the diamond is defined as a length perpendicular to the table of the diamond and passing through a central axis of a vertex of a pavilion of the diamond;
(ii) detecting, in a processor module, a defect within the body of the diamond, wherein the defect is detected from a contrast change in pixel brightness levels compared to adjacent pixels in images acquired from each of the plurality of top view images; applying a penalty score to each detected defect based on the geometry, size and location of said defect within the body of said diamond; and assigning a net rating based on a function of the penalty score; and
(iii) (iii) providing a signal from an output module indicative of the clarity grade assigned in (ii).
2. The method of claim 1, wherein the height of said diamond is determined by an optical image, said optical image being acquired via another optical image acquisition device positioned perpendicular to said central axis of said diamond.
3. The method of claim 1 or claim 2, wherein the apparent depth of focus D for focusing is corrected according to the following formulaapparent：
Wherein n isdiamond≈2.42。
4. The method according to any of the preceding claims, wherein the predetermined constant light level is a color temperature of 6500K.
5. A method according to any one of the preceding claims wherein the plurality of top view images of a diamond are acquired within a system of integrating spheres.
6. The method according to any of the preceding claims, wherein the light source providing the predetermined light level is selected from the group comprising LED (light emitting diode) light sources, xenon and incandescent light sources as well as fluorescent light sources, solar simulators, etc.
7. The method according to any one of the preceding claims, wherein the optical image acquisition device is a digital camera.
8. The method according to any of the preceding claims, wherein the optical image acquisition device is monochromatic or polychromatic.
9. A computerized system for grading the clarity of a diamond according to internal imperfections within the body of the diamond, the computerized system comprising:
optical image acquisition means for acquiring a plurality of top view images of the diamond with different focus depths corrected by the refractive index of the diamond, wherein the focus depth is determined by the height of the diamond and the plurality of top view images are acquired in an environment with a predetermined constant light level, and wherein the top view is defined as a view perpendicular to the table of the diamond and the height of the diamond is defined as a length perpendicular to the table of the diamond and passing through the central axis of the apex of the pavilion of the diamond;
a processor module for detecting a defect within the body of the diamond, wherein the defect is detected from a contrast change in pixel brightness levels compared to adjacent pixels in images acquired from each of the plurality of top view images; and for applying a penalty score to each detected defect based on the geometry, size and location of said defect within the body of said diamond; and for assigning a net rating based on a function of the penalty score; and
an output module that provides a signal indicative of the clarity grade assigned to the diamond.
10. The computerized system of claim 9, wherein said processor module comprises a data repository comprising a plurality of data sets indicating dates related to known defect types of diamonds.
11. The computerized system according to claim 9 or claim 10, wherein said processor module is located at a location remote from said optical image acquisition device and said output module and communicates with said optical image acquisition device and said output module by means of a telecommunications network.
12. The computerized system according to any of claims 9 to 11, further comprising a light source for providing said predetermined constant light level, said predetermined constant light level being a color temperature of 6500K.
13. The computerized system according to claim 12, wherein said light source is selected from the group comprising LED (light emitting diode) light sources, xenon and incandescent light sources, and fluorescent light sources, solar simulators, etc.
14. The computerized system according to any of claims 9 to 13, further comprising a system of integrating spheres in which the diamond is positioned when at least the first optical image is acquired.
15. The computerized system according to any of claims 9 to 14, further comprising a rotation platform rotatable around said central axis and within the system of integrating spheres, wherein said rotation platform provides rotation of said diamond around said central axis such that a plurality of optical images of said diamond can be acquired by said optical image acquisition device.
16. The computerized system according to any of claims 9 to 15, wherein said optical image acquisition device is a digital camera.
17. The computerized system according to any of claims 9 to 16, wherein said optical image acquisition device is monochromatic or polychromatic.
18. A computerised system according to any of claims 9 to 17, further comprising a further optical acquisition device for acquiring an optical image of a side view of the diamond so as to allow the height of the diamond to be determined.
Technical Field
The present invention relates to a system and method for determining the cleanliness of a gemstone. More specifically, the present invention provides a system and method for determining the clarity of a diamond.
Background
Diamonds are a key ingredient utilized in luxury goods, especially jewelry and jewelry, and can be of great value. The value of a diamond depends on several physical properties of the diamond.
There are four globally accepted standards for assessing the quality of diamonds (commonly referred to as 4C) which are clarity, color, cut and carat weight.
As an example, the american gem association (GIA) has a clarity rating as shown below:
in order to assess the clarity of a diamond, the number, size and location of defects within the stone material need to be determined.
Different defects can be formed from the conditions under which the diamond is formed in the soil to the human application method performed on the diamond.
Inside the diamond body, there may be impurities, voids and cracks that are considered internal defects. On the surface of the diamond, there may be under-polished irregularities and scratches that are considered as external defects.
These internal and external features are also important for the diamond as it can be one of the unique identification marks or "birthmarks" that can be used to identify the diamond.
Currently, the most accepted practice for determining the clarity of a diamond is through a trained human eye under a 10-fold microscope. Gemstone appraisers have been trained for several months using standard samples with different types of defects, in the hope that the stone should reproduce the same evaluation results when evaluated by different persons.
However, even under standardized training and evaluation procedures, repeatability cannot be guaranteed due to inevitable subjective human judgment.
The same individual evaluating the same diamond at different times may also result in different clarity grades being applied to the same diamond. Due to the visual fatigue of people, the same diamond can also be judged differently before and after the evaluation of many different stones.
Thus, even for trained and experienced professional gemstone appraisers, these gemstone appraisers still experience the challenge of providing repeatability in the cleanliness assessment.
Object of the Invention
It is an object of the present invention to provide a system and method for determining the clarity of a gemstone, particularly a diamond, which overcomes or at least ameliorates at least some of the disadvantages as associated with the prior art.
Disclosure of Invention
In a first aspect, the present invention provides a method operable using a computerised system for grading the clarity of a diamond according to internal imperfections within the body of the diamond, the computerised system comprising an optical image acquisition device, a processor module and an output module operatively interconnected together, the method comprising the steps of:
(i) acquiring, via an optical image acquisition device, a plurality of top view images of the diamond having different depths of focus corrected with the refractive index of the diamond, wherein the depth of focus is determined by the height of the diamond, and the plurality of top view images are acquired in an environment having a predetermined constant light level, and wherein the top view is defined as a view perpendicular to the table of the diamond, and the height of the diamond is defined as a length perpendicular to the table of the diamond and passing through a central axis of a vertex of a pavilion of the diamond;
(ii) detecting, in a processor module, a defect within the body of the diamond, wherein the defect is detected from a contrast change in pixel brightness levels compared to adjacent pixels in images acquired from each of the plurality of top view images; applying a penalty score to each detected defect based on the geometry, size and location of the defect within the body of the diamond; and assigning a net rating based on a function of the penalty score; and
(iii) (iii) providing a signal from the output module indicative of the clarity grade assigned in (ii).
Preferably, the height of the diamond is determined by an optical image acquired via another optical image acquisition device positioned perpendicular to the central axis of the diamond. Preferably, the apparent depth of focus D for focusing is corrected according to the following formulaapparent：
Wherein n isdiamond≈2.42。
Preferably, the predetermined constant light level is a color temperature of 6500K.
Preferably, multiple top view images of the diamond are acquired within the system of integrating spheres.
Preferably, the light source providing the predetermined light level is selected from the group comprising: LED (light emitting diode) light sources, xenon light sources, incandescent light sources, fluorescent light sources, solar simulators, and the like.
Preferably, the optical image capturing device is a digital camera.
The optical image acquisition device may be monochromatic or polychromatic.
In a second aspect, the present invention provides a computerised system for grading the clarity of a diamond according to internal imperfections within the body of the diamond, the computerised system comprising:
an optical image acquisition device for acquiring a plurality of top view images of the diamond having different depths of focus corrected by the refractive index of the diamond, wherein the depth of focus is determined by the height of the diamond and the plurality of top view images are acquired in an environment having a predetermined constant light level, and wherein the top view is defined as a view perpendicular to the table of the diamond and the height of the diamond is defined as a length perpendicular to the table of the diamond and passing through a central axis of a vertex of a pavilion of the diamond;
a processor module for detecting defects within the body of the diamond, wherein defects are detected from contrast changes in pixel brightness levels compared to adjacent pixels in images acquired from each of the plurality of top view images; and the processor module is for applying a penalty score to each detected defect according to the geometry, size and location of the defect within the body of the diamond; and the processor module for assigning a cleanliness ranking based on a function of the penalty scores; and
an output module that provides a signal indicative of the clarity grade assigned to the diamond.
The processor module may comprise a data repository comprising a plurality of data sets indicating dates relating to known defect types of diamonds.
The processor module may be located remotely from the optical image acquisition device and the output module and communicate with the optical image acquisition device and the output module by way of a telecommunications network.
Preferably, the computerized system further comprises a light source for providing said predetermined constant light level, which is a color temperature of 6500K. The light source may be selected from the group comprising: LED (light emitting diode) light sources, xenon light sources, incandescent light sources, fluorescent light sources, solar simulators, and the like.
Preferably, the computerized system further comprises a system of integrating spheres in which the diamond is located when the at least first optical image is acquired.
The computerized system may further comprise a rotation platform rotatable about said central axis and within the system of integrating spheres, wherein the rotation platform provides rotation of the diamond about the central axis such that a plurality of optical images of the diamond may be acquired by the optical image acquisition device.
The optical image capturing device may be a digital camera.
The optical image acquisition device may be monochromatic or polychromatic.
Preferably, the computerized system further comprises a further optical acquisition device for acquiring an optical image of a side view of the diamond in order to allow the height of the diamond to be determined.
Drawings
In order that a more particular understanding of the invention described above may be obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings. The figures presented herein may not be drawn to scale and any reference to dimensions in the figures or the following description is specific to the disclosed embodiments.
Fig. 1 shows a schematic representation of an embodiment of a system according to the invention;
FIG. 2a shows a flow chart of a method according to the invention;
FIG. 2b shows a representation of a flow chart of an embodiment of a method according to the invention; and
fig. 3a, 3b and 3c schematically depict embodiments of the method according to the invention.
Detailed Description
The present inventors have identified shortcomings in the manner in which clarity grading of diamonds is performed, and having identified problems of the prior art, have provided a system and method that overcomes the problems of the prior art, and provides a more consistent and reliable system and method.
Referring to fig. 1, there is shown a schematic representation of a system 300 according to the present invention. The system 300 includes an optical image acquisition device 310, the optical image acquisition device 310 in communication 312 with a processor module including a processor 320, the processor module in communication 322, 332 with a data repository 330, the data repository 330 storing a plurality of data sets relating to defects. An output device 340 is provided, the output device 340 in communication 324 with the processor 320.
The system 300 includes a system integrating sphere 350 in which the diamond 315 is located when multiple optical images are acquired.
The optical image acquisition device 310 is a digital camera device or other device (such as a CCD camera, etc.) that allows for the acquisition of an optical image of the diamond 315.
The system 300 comprises a light source 318 for providing said predetermined constant light level, which is a color temperature of 6500K. The light source is selected from the group comprising: LED (light emitting diode) light sources, xenon light sources, incandescent light sources, fluorescent light sources, solar simulators, and the like.
The system 300 further comprises a rotation platform 317 rotatable around said central axis of the diamond 315 and within the system of integrating spheres 350, wherein the rotation platform 317 provides rotation of the diamond around the central axis such that a plurality of optical images of the diamond may be acquired by the optical image acquisition device 310.
Referring now to fig. 2a, in fig. 2a flow chart of an embodiment of the
The
The
a first step 210 a-acquiring, via an optical image acquisition device, a plurality of top view images of the diamond with different depths of focus corrected by the refractive index of the diamond, wherein the depth of focus is determined by the height of the diamond, and acquiring the plurality of top view images in an environment with a predetermined constant light level.
The top view is defined as the view perpendicular to the table of the diamond and the height of the diamond is defined as the length of the central axis perpendicular to the table of the diamond and passing through the apex of the pavilion of the diamond.
Second step 220 a-in the processor module,
(i) detecting a defect within the body of the diamond, wherein a defect is detected from a contrast change in pixel brightness levels compared to adjacent pixels in each acquired image of the plurality of top view images; and
(ii) applying a penalty score to each detected defect based on the geometry, size and location of the defect within the body of the diamond; and assigning a net rating based on a function of the penalty score.
A
The height of the diamond may be determined by an optical image acquired via another optical image acquisition device positioned perpendicular to the central axis of the diamond.
Correcting the apparent depth of focus D for focusing according to the following formulaapparent：
Wherein n isdiamond≈2.42。
With the stone height deduced from the side view image, multiple images of the diamond at different depths of focus can be captured perpendicular to the table to detect defects. This can be done by dividing the height of the diamond into corresponding depth of focus. However, since the side view image is captured in air, while the image perpendicular to the table will be captured in a diamond, air (n)air1) and diamond (n)diamond2.42) may affect the depth of focus determination. Taking the approximation of the angle of incidence of the light rays small relative to the image captured perpendicular to the mesa, the apparent depth D for focusing can be madeapparentThe correction is as follows:
not the true depth Dreal.
The predetermined constant light level is a range of color temperatures of 6500K.
Acquiring a plurality of top view images of the diamond within a system of integrating spheres and providing the predetermined light level to a light source selected from the group consisting of: LED (light emitting diode) light sources, xenon light sources, incandescent light sources, fluorescent light sources, solar simulators, and the like.
Referring now to fig. 2b, in the illustrated embodiment, the following steps are utilized:
step (i)210b — acquiring a side view of the diamond;
step (ii)220b — obtaining a plurality of mesa view images at different focus depths;
step (iii)230b — determining sharp changes in pixel brightness, which do not include those changes caused by diamond cuts;
step (iv)240b — assigning a penalty score to each defect; and
step (v)250 b-the sum of the penalty scores is used to determine the clarity grade of the diamond.
As shown in fig. 3a, from a side view of the height of diamond 400, a plurality of images of table 410 at different depths of focus 1 to 5 corresponding to the first step of the method are shown. The height h of the diamond is determined by a side view, which may be acquired by an image acquisition device, such as a digital camera or a CCD camera.
Subsequently, as shown in fig. 3b, defects are detected within the bulk of diamond 400, wherein according to the method of the present invention, defects are detected from the contrast change in pixel brightness levels compared to adjacent pixels in each acquired image of the plurality of top view images.
However, the abrupt change in brightness caused by cutting the stone material, such as at region 420, is not included and is not considered a defect, while the abrupt change in brightness, such as in the middle of the facet (such as region 430), is considered a defect.
Subsequently and as further shown in figure 3c, a penalty score is applied to each detected defect according to the geometry, size and location of the defect within the body of diamond 400; such as scores represented by the numbers 2, 3, 4, and 5 as depicted in fig. 3c, and a net rating is assigned based on a function of the penalty scores.
A clarity grade may then be assigned to diamond 400.
As shown, to overcome the repeatability and reliability difficulties of the prior art, an embodiment of the method of the present invention using a system of integrating spheres was used to analyze the clarity of the diamond.
Such a method implemented in a machine system (without the problem of human visual fatigue and with an algorithm for analyzing defects) provides an improved and advantageous alternative with high repeatability compared to the prior art.
The system and method of the present invention also reduces the cost and time of producing a collection of primary stones and training a professional gemstone appraiser. This may also reduce the time for training professional gemstone appraisers for purity grading.
Due to the clarity and the inherent differential visual properties, assessment of the clarity of a diamond needs to be done in a controlled environment. This ensures that the lighting conditions and background are the same for each diamond, as provided by the present invention.
Furthermore, the controlled environment must be repeatable at different locations so that people at different locations can still have the same assessment of the clarity of the diamonds provided by the present invention.
The system of integrating spheres helps to do this as the light intensity, spectrum and uniformity can be well controlled and repeated as utilized in the preferred embodiment of the invention, and therefore, the system of the invention can be used and allows for cleanliness assessment.
In summary, a preferred embodiment of the method of the invention is as follows:
1. from the side view camera (camera 3 or 6 as shown in fig. 1) a photographic representation of the height of the stone is deduced.
2. Using this height information, a table view camera (such as camera 1 shown in fig. 1) would be useful to obtain multiple (e.g. 5) pictures of different depths of focus (from the table top to the pavilion tip, as described above) corrected for the refractive index of the diamond.
3. The above 2 nd point photographed image is analyzed, and a defect in the stone located in the photographed image as an abnormal pixel is determined. Anomalies refer to sharp changes in the brightness level of the pixels compared to the surrounding pixels, but excluding those changes caused by stone cuts.
4. Then, a penalty score is assigned to each defect found, depending on its location and size. The sum of the penalties determines the final grading of the stone.
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