Image analysis process and system
阅读说明：本技术 图像分析工艺和系统 (Image analysis process and system ) 是由 郑家荣 黄健荣 陈江 程娟 邓咏芝 许冠中 于 2019-01-17 设计创作，主要内容包括：一种用于获取物品的图像的图像获取系统,所述系统包括用于获取物品的图像的光学图像获取设备,其中所述物品至少是部分透明的；第一光源,用于使光透射通过所述物品；第一线性偏振器和第二线性偏振器,其中所述第一线性偏振器和所述第二线性偏振器被设置在光学图像获取设备和第一光源之间,第一线性偏振器被设置在第一光源的近端且第二线性偏振器被设置在第一光源的远端并邻近光学图像获取设备；以及物品支撑构件,该物品支撑构件被设置在第一线性偏振器和第二线性偏振器之间以支撑物品,其中物品支撑构件是光学透明的；其中所述第一线性偏振器和所述第二线性偏振器以彼此交叉的定向可操作地被定向,使得从第一光源发射的光基本上被防止由光学图像获取设备接收；以及其中在物品由物品支撑构件支撑以后,物品更改由第一线性偏振器偏振的光的偏振,使得物品可由图像获取设备光学地检测,并且使得图像可由包括与获取物品的图像所针对的背景形成对比的物品的图像获取设备获取。(An image acquisition system for acquiring an image of an article, the system comprising an optical image acquisition device for acquiring an image of an article, wherein the article is at least partially transparent; a first light source for transmitting light through the article; a first linear polarizer and a second linear polarizer, wherein the first linear polarizer and the second linear polarizer are disposed between the optical image acquisition device and the first light source, the first linear polarizer is disposed proximal to the first light source and the second linear polarizer is disposed distal to the first light source and adjacent to the optical image acquisition device; and an article support member disposed between the first linear polarizer and the second linear polarizer to support the article, wherein the article support member is optically transparent; wherein the first and second linear polarizers are operably oriented in a crossed orientation with respect to each other such that light emitted from the first light source is substantially prevented from being received by the optical image acquisition device; and wherein after the item is supported by the item support member, the item alters the polarization of the light polarized by the first linear polarizer such that the item is optically detectable by the image acquisition device and such that an image is acquirable by the image acquisition device comprising the item in contrast to a background against which the image of the item was acquired.)
1. An image acquisition system for acquiring an image of an article, the system comprising:
an optical image acquisition device for acquiring an image of an article, wherein the article is at least partially transparent;
a first light source for transmitting light through the article;
a first linear polarizer and a second linear polarizer, wherein the first linear polarizer and the second linear polarizer are disposed between the optical image acquisition device and the first light source, the first linear polarizer is disposed proximal to the first light source, and the second linear polarizer is disposed distal to the first light source and adjacent to the optical image acquisition device; and
an article support member disposed between the first and second linear polarizers to support the article, wherein the article support member is optically transparent;
wherein the first and second linear polarizers are operably oriented in a crossed orientation with respect to each other such that light emitted from the first light source is substantially prevented from being received by the optical image acquisition device; and
wherein, after the item is supported by the item support member, the item alters the polarization of light polarized by the first linear polarizer such that the item is optically detectable by the image acquisition device and such that an image including the item contrasted with a background against which the image of the item was acquired is acquirable by the image acquisition device.
2. The system of claim 1, wherein,
the system further includes a second light source disposed between the first and second linear polarizers to illuminate the item such that, upon removal of the polarizers, and by the optical acquisition device, an optical image of the item indicative of the color of the item can be acquired.
3. The system of claim 2, wherein,
the first and second light sources provide light of constant color and intensity to provide uniform lighting conditions.
4. The system of claim 2 or claim 3, wherein the first and second light sources are selected from the group comprising:
LED light sources, xenon light sources, halogen light sources, deuterium light sources, incandescent light bulb light sources, fluorescent light sources, solar simulator light sources, and the like.
5. The system of any one of claims 2 to 4, wherein the system comprises an integrating sphere system comprising two spheres interconnected at an aperture to provide communication therebetween,
wherein the first light source is in communication with a first sphere and the second light source is in communication with a second sphere, and,
wherein the optical image acquisition device is directed towards the aperture from an edge of the second sphere,
wherein the first linear polarizer blocks the aperture between the two spheres and the second linear polarizer blocks the optical image acquisition device, and,
wherein the article support member is disposed adjacent to the first linear polarizer.
6. The system of any one of the preceding claims, wherein,
the first and second linear polarizers are movable to allow an image of the item to be acquired in the absence of polarized light.
7. The system of any one of the preceding claims, wherein,
the article support member is formed of glass, quartz, or a polymer material.
8. The system of any one of the preceding claims, wherein,
the item support member comprises an optical filter including a neutral density filter, an anti-reflection filter, a UV reflection filter, or the like.
9. The system of any one of the preceding claims, further comprising:
a further support member for supporting the item support member.
10. The system of claim 9, wherein,
the further support member is formed from glass, quartz or a polymer material.
11. The system of claim 9 or claim 10,
the further support member comprises a filter comprising a neutral density filter, an anti-reflection filter, a UV-reflection filter or the like.
12. The system of any one of the preceding claims, wherein,
the optical image acquisition device is in communication with a processor to analyze the color of the item.
13. The system as set forth in claim 12, wherein,
wherein the processor is in communication with a data store, and,
wherein the data store comprises standardized reference data indicative of a range of colors, and
wherein the processor quantitatively associates pixel color values of the image of the item acquired by the optical image acquisition device with the standardized reference data.
14. A process operable with a computerized system to grade a color of an article, wherein the article is at least partially transparent, and wherein the color of the article is associated with a color from a set of standardized reference color data, the computerized system comprising an optical image acquisition device, a processor module, and an output module operatively interconnected together, the process comprising the steps of:
(i) acquiring, via an optical image acquisition device, a background image of an environment in which an image of the item is to be acquired, and acquiring an item image of the item in the environment, wherein the environment has a predetermined constant light level;
(ii) acquiring a mask image via the optical image acquisition device,
wherein the mask image is an optical image of the article containing a background against which the image of the article was taken,
wherein the mask image is acquired with the article disposed between a first linear polarizer and a second linear polarizer,
wherein the first and second linear polarizers are disposed between the optical image acquisition device and a first light source, the first linear polarizer is disposed proximal to the first light source, and the second linear polarizer is disposed distal to the first light source and adjacent to the optical image acquisition device,
wherein the first and second linear polarizers are operably oriented in a crossed orientation with respect to each other such that light emitted from the first light source is substantially prevented from being received by the optical image acquisition device; and is
Wherein the article alters the polarization of light polarized by the first linear polarizer such that the article is optically detectable by the image acquisition device and such that the mask image comprising the article against which the image of the article was acquired is acquirable by the image acquisition device;
(iii) in the context of the processor module,
(a) removing the background from the item image using the acquired mask image and correcting the item image by flat field correction using the background image, an
(b) Comparing data derived from the acquisition of the image of the article that has been corrected with data from it with the set of standardized reference color data;
(iv) providing an output signal from an output module indicative of a color of a region of the item in response to a predetermined threshold of correlation between the pixel color values of the region of the item and data derived from the input of the first optical image and assigning a color to the region of the item.
15. The process of claim 14, wherein,
acquiring the background image, the item image and the mask image via a system according to any one of claims 1 to 13.
16. The process of claim 14 or claim 15,
the pixel color values of the item are reference color definitions including those of the groups RGB, HSL, HSV, CIE, CMYK, YIQ, and the like.
17. The process of any one of claims 14 to 16,
the articles are gemstones, including precious gemstones, semi-precious gemstones, and ornamental stones.
Technical Field
The present invention relates to a system and process for analysing the visual properties of a gemstone. More particularly, the present invention provides a system and process for analyzing the color characteristics of a gemstone article formed of precious stones (precious stones), semi-precious stones (semi-precious stones), or ornamental stones.
Background
Color judgment of the color of an object or article is a very important process in the evaluation of persons of the object or article, and the optical parameter used for the evaluation and grading of gemstones is color, in particular for luxury items such as gemstones and articles formed from gemstones.
The assessment and grading of optical parameters of gemstones, particularly color, is used in the gemstone industry to represent a grade that contributes to the value of the gemstone or an article formed from the gemstone material, and which is highly dependent on color. Thus, for consistency of color grading, repeatable and reliable color judgment is required.
However, color recognition is a complex parameter for people, and wrong judgments with color are common between different people and when the same person performs evaluation, and such inconsistencies may lead to conflicts and may lead to misclassification.
For certain types of gemstones, particularly diamonds, there are color grading scales established and accepted in the industry. It is referred to as colorless. The more colorless the diamond, the higher the grade. For example, the american society for Gem (GIA) color grading has a D to Z color grading, and a master (master set) of stones is used for visual comparison in order to grade diamonds by their color.
In other color grading systems, a standard data set in the form of a color chart or chart is employed for visual comparison again with the gemstone or item.
In such cases, repeated training of the color grader is required so that different graders can reproduce the same evaluation in an effort to provide uniformity and consistency among the color grader.
However, in any event, different graders may provide different or varying color assessments as a person grades a gemstone or item. Moreover, the same grader may also provide inconsistent results for the same gemstone or item, and such inconsistencies may result in incorrect grading, which may adversely affect the value of the gemstone or item, as well as other commercially unacceptable consequences.
Disclosure of Invention
OBJECT OF THE INVENTION
It is an object of the present invention to provide a system and process for analysing a visual characteristic, in particular colour, of a gemstone that overcomes or at least partially ameliorates at least some of the disadvantages associated with the prior art.
Drawings
In order that the manner in which the above recited invention is attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the specific embodiments thereof which are illustrated in the appended drawings. The drawings presented herein may not be to scale and any reference to dimensions in the drawings or the following description is specific to the disclosed embodiments.
FIG. 1 shows a schematic diagram of a system and process according to the present invention;
FIG. 2 shows an embodiment of a system according to the invention; and
figures 3a, 3b and 3c show representations of quantitative exams showing the correlation between H, S, L values and standard Pantone color values between acquired images using the system of the present invention.
Detailed Description
Background on color
For colored objects or items, human judgment and interpretation of color can be severely affected by the lighting conditions under which the object or item is viewed. One important condition is the color of the ambient light. The color of the light can be accurately described by a spectrum. In practice, for simplicity, the color of light can be described by its color temperature, which shows the spectrum emitted by an ideal black-body radiator at a particular temperature.
For white light, the spectrum is similar to the solar spectrum, with a spectrum temperature of 6500K. Under lighting conditions with different colors, such as yellow light (e.g., an incandescent lamp with a light temperature of 3000K) and white light (e.g., sunlight with a light temperature of 6500K), the colors of objects observed by the human eye may be quite different.
Another important light condition is light intensity. Even under light of the same color (e.g., white light), the light intensity variations can significantly affect a person's judgment of the color or colors of an object or item. If the lighting conditions are not uniform, testing or viewing the environment can be much more complex. Thus, for human evaluation of color, a standard environment is required to obtain repeatable and reliable results.
Problem of color judgment or evaluation
In addition, in the color judgment and interpretation of a person, misunderstanding or misinterpretation may occur between different persons. For example, some people may classify them as "blue" and some people may classify them or consider them as "green" for the same cloth, meaning that the "reference table" of two people may be different for one color or multiple colors.
Therefore, human judgment of color must be done with the same basis and terminology. Reference masters with different colors can be used for this purpose. The reference masters each require a high degree of accuracy and repeatability from master to master. Each reference master must be uniformly saturated with a particular standard color so that an optimal comparison can be made between the object or item to be graded and the reference master.
For the color grading assessment of gemstones, the accuracy and availability of the colorimetric stones as reference sets applies not only to different sets of reference masters, but also to the same set of reference masters at different points in time when the assessment was made, since it has been found that the color of the reference stones in the masters may vary over time.
Thus, the color of the reference master must be permanent and not change over time, otherwise the reference master must be provided with a usable or serviceable life span.
After the availability or useful life of the reference master has expired, there is no guarantee that the color will remain stable and therefore the accuracy and repeatability of the color grading assessment is not guaranteed.
Furthermore, even under well-controlled conditions, such as constant light color, intensity, uniform illumination and a good reference master, determining color using the human eye may still be a problem for correct color judgment of an object or item.
Different color judgments of the same object or item at different times may have different results due to the fatigue of the person's vision. A person viewing an object after viewing many other different colored objects or items may give a different color assessment than if viewing a different history.
For color perception, it is a common psychological effect to increase the variation of human judgment on color. The change in color perception is particularly severe if the object or article has a matrix of various colors or is multi-colored. In the case where the background color exists, a person can easily misjudge the color.
Thus, during the color determination process, the object or item being evaluated should be placed on a background having a uniform color (such as white) to minimize the variation in color perception.
However, for objects or articles with different color matrices, the color perception cannot be eliminated. These psychophysiological problems make it impossible for the human eye to make a repeatable and reliable color judgment.
Therefore, for a system capable of converting light into "color" information, which includes an image acquisition device such as a camera, some special processing of the image needs to be taken, and some processing such as not directly outputting the wavelength of light for that reason is also needed.
Recognized disadvantages of the prior art
The present inventors have recognized the shortcomings of the manner in which the color of gemstones is evaluated, and having recognized the problems of the prior art, have provided systems and processes that overcome the problems of the prior art, and provide more consistent and reliable systems and processes.
The problems recognized by the present inventors include:
(i) as described aboveIntrinsic factorIncluding the requirement that the colors must be precise, saturated and consistent between masters, which may be reference cards or the metamers of a chart;
(ii)extrinsic factorIncluding the environment in which the color judgment assessment is made, including lighting conditions and background; and
(iii) relating to human judgmentExtrinsic factorIncluding misjudgment due to environment, human perception, human consistency, fatigue, and distraction, as well as inherent human error.
The invention
To address the above-mentioned shortcomings, including repeatability and reliability difficulties, the present invention provides a process and system for determining and analyzing the color of an object or article, particularly a gemstone.
The system provides well-controlled lighting conditions over time and provides machine or electronic vision without vision, without the inherent drawbacks and inconsistencies of human visual fatigue. Such a process and system provide advantages over the prior art and provide high repeatability for analyzing the color of an object or article.
Referring to fig. 1, there is shown a schematic representation of an image acquisition system 100 according to the present invention, the image acquisition system 100 being used to acquire an image of an article 110, in particular a gemstone.
The system comprises:
an optical image acquisition device 104 for acquiring an image of an item 110, wherein the item 110 is at least partially transparent; and
a first light source 102 is provided for transmitting light through the article 110.
The system further comprises a first linear polarizer 106 and a second linear polarizer 108, wherein the first linear polarizer 106 and the second linear polarizer 108 are arranged between the optical image acquisition device 104 and the first light source 102. A first linear polarizer 106 is disposed proximal to the first light source 102 and a second linear polarizer 108 is disposed distal to the first light source 102 and adjacent to the optical image acquisition device 104.
An article support member (not shown) for supporting the article 106 is disposed between the first linear polarizer 106 and the second linear polarizer 108, wherein the article support member is optically transparent.
First linear polarizer 106 and second linear polarizer 108 are operably oriented in an orientation that crosses each other such that light emitted from first light source 102 is substantially prevented from being received by optical image acquisition device 104.
After article 110 is supported by the article support member, the article alters the polarization 116 of light 114 polarized by first linear polarizer 106 such that the article is optically detectable by image acquisition device 104 and such that an image including article 110 contrasted with the background against which the image of the article was acquired may be acquired by image acquisition device 104.
Referring to FIG. 2, a schematic representation of an embodiment of a
The inner coating of each integrating
For the
In communication with the
For the
A
In accordance with the process of the present invention, when an optical image of
An empty background image is first acquired via camera 220 (in this case a digital camera) and then a second optical image is acquired with
The second acquired optical image may be flat field corrected using the acquired empty background image. Flat field correction is a well known method of removing non-uniformities between different pixels of an image. This difference consists of two sources. One source is the sensitivity variation between different pixels on the camera detector, while the other source is the contribution of optical distortions, such as the optical distortion of the lens. After flat field correction of the image, the image can achieve high quality.
To contrast the
The two
In accordance with the present invention, in the presence of an
Similarly, as described with reference to fig. 1, only light passing through the
This process of the present invention physically enhances the image contrast between the
The present inventors have recognized that by using the actual physical shape and geometry of the at least partially optically
When using computational methods for background removal, complex image analysis is required and does not always provide a clear distinction between the background and the item for which subsequent image analysis is required.
The inventors have utilized the diffractive properties of the article, which correspond exactly to the edges of the article, in order to create an effective mask for background removal.
The inventors have found that a very precise edge of an article can be determined based on light and physical effects without the need for complex algorithms, and the invention has proved to be particularly useful for determining the optical properties of a gemstone, in particular the colour of a gemstone.
For gemstones that require color assessment, such as emerald, where the color of the article may change (including at the edges), and where the article may have a white color, it is often difficult to delineate between the background and the article, and when the colors are similar, image analysis software that typically determines the edges using interpolation between optical parameters cannot easily accurately distinguish between the background and the article.
In contrast, the process of the present invention is not affected by such color difference errors because even if the article has the same color at the edges as the background, the diffractive nature of the article allows the article to be viewed via the camera while blocking the background due to the implementation of two 90-degree polarizing polarizers.
To determine whether the system of the present invention can provide the correct color and provide stable performance without drift, a standard color reference is used.
Standard color references are spectrally calibrated by the issuing authority so that their color values are truly associated with the pixel color values in the images captured by the system. This is particularly important for consistent and accurate color determination as different optical acquisition devices, such as cameras, since different brands of cameras may have different imaging capabilities.
The quantitative check may be accomplished by determining a correlation between color values determined by the spectra acquired by the system of the present invention and pixel color values.
Referring to fig. 3a, 3b and 3c, an example of a quantitative check showing the correlation of H, S, L values between an image acquired using a camera of the system of the present invention and a Pantone color reference is shown.
By means of a quantitative check, the performance of different systems can be compared and calibrated, so that a repeatable and reliable classification can be performed without human judgment.
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