WO2019197952A1

WO2019197952A1 - Apparatus and method for determining physical and chemical parameters of an unhomogeneous sample through acquisition and processing of colour images of the sample

Info

Publication number: WO2019197952A1
Application number: PCT/IB2019/052810
Authority: WO
Inventors: Alessandro ULRICI; Rosalba CALVINI; Giorgia FOCA; Giorgia ORLANDI; Andrea Antonelli
Original assignee: Universita' Degli Studi Di Modena E Reggio Emilia
Priority date: 2018-04-13
Filing date: 2019-04-05
Publication date: 2019-10-17
Also published as: IT201800004498A1

Abstract

An apparatus (1) for determining at least one physical parameter and/or at least one chemical parameter of a sample of a chromatically unhomogeneous material or product comprises a controlled lighting image acquisition chamber (2), said controlled lighting image acquisition chamber (2) comprising a sample insertion and removal portion (2a) and an image acquisition portion (2b). A method for determining at least one physical parameter and/or at least one chemical parameter of a sample of a chromatically unhomogeneous material or product comprises the following steps: positioning said sample inside an apparatus (1) comprising a controlled lighting image acquisition chamber (2), in said controlled lighting image acquisition chamber (2) an operating chamber (11) being comprised that can be separated from the external environment and the ambient luminosity and is arranged for receiving said sample; acquiring an RGB digital image of said sample through an image acquisition device; processing said acquired RGB digital image, said processing comprising: correcting said acquired RGB digital image, converting said acquired and corrected RGB digital image into a corresponding one-dimensional signal describing the colour contents of said image, applying a multivariate calibration model to said one-dimensional signal, said multivariate calibration model being specific for said at least one physical parameter and/or said at least one chemical parameter, said applying comprising comparing said one-dimensional signal with said multivariate calibration model, and obtaining estimated values of said at least one physical parameter and/or said at least one chemical parameter through said comparing.

Description

Apparatus and method for determining physical and chemical parameters of an unhomogeneous sample through acquisition and processing of colour images of the sample

[0001] The invention relates to an apparatus and a method for determining physical and chemical parameters of an unhomogeneous sample, in particular of a sample of chromatically unhomogeneous product or material, through acquisition and processing of colour images of the sample.

[0002] It is known that the chromatic appearance of a material or product, such as for example a food material or product, depends on the chemical and physical properties exhibited by the latter and can thus vary, even significantly, as a result of variations in the aforesaid properties. Therefore, a chromatic variation in comparison with a reference colour can indicate, for example, the nonconformity of an industrial product (for example, a ceramic tile) with a preset standard or the reaching of a desired degree of ripeness of a natural product (for example a food product of vegetable origin).

[0003] It is possible to analyze colour images of a product (for example, a food product) by using colorimetric apparatuses and methods for the purpose of collecting useful information on the state of the product (for example, variations of organoleptic properties, state of ripeness and/or conservation). In particular, the known colorimetric apparatuses and methods enable the reflectance, transmittance or absorbance properties of samples of the product to be quantified.

[0004] A drawback of the known apparatuses and methods is that the latter are able to analyze only substantially restricted surface areas of the sample (spot colorimeters). Another drawback of the known apparatuses and methods is that the latter can perform an overall evaluation of the colour for every single analyzed surface portion of the sample (integrating spheres), but are not able to provide useful information on the local chromatic variability. As a consequence of the aforesaid drawbacks, the known apparatuses and methods are not suitable for use for the analysis of unhomogeneous samples, in particular samples of chromatically unhomogeneous materials or products, both of food and non-food origin.

[0005] Grapes are an example of a chromatically unhomogeneous product, the colours of which cannot be analyzed effectively by using the aforementioned known colorimetric apparatuses and methods. As it is known, the degree of ripeness of grapes at the time of the vintage is the first factor that influences the quality of the resulting wine. Although the levels of sugars, pH and acidity are the parameters most frequently used to monitor the degree of ripeness of grapes, also the phenolic composition of the latter plays an important role in the development of several sensory properties of the wine, such as colour, body, structure, bitterness and astringency.

[0006] An expert vine-grower could carry out a first, rough evaluation of the degree of ripeness of the grapes in the field through a visual evaluation. In fact, the anthocyans (or anthocyanins) are the vegetable pigments responsible for the (purplish red) colouring of ripe red grapes and the content of the anthocyans increases as the grapes ripen. However, an evident drawback connected with the visual evaluation is that the latter is intrinsically subjective and thus hardly reliable and reproducible. Moreover, the reliability and reproducibility of the visual evaluation are further limited by the fact that berries (grapes) having different colouring are generally present on the same plant or on the same bunch.

[0007] As a result, the determination of the phenolic parameters in the grape is carried out by using known analytical methods, in particular spectrophotometric and chromatographic analyses. The carrying out of the latter always requires that the sample to be analyzed (grape berries) is first homogenized mechanically and then destroyed.

[0008] A drawback of the known analytical methods is that they require the use of costly devices and apparatuses (UV-VIS spectrophotometers; HPLC systems), which have to be run by suitably qualified personnel and inside specialized laboratories, as well as the use of chemical reagents, which have to be subsequently disposed of suitably to avoid significant qualitative and quantitative alterations to the environment.

[0009] Another drawback is that the aforesaid laboratory analyses represent an additional cost for vine-growing and wine-making businesses and require a not negligible execution time, which is comprised between dozens of minutes and some hours. Moreover, the need to determine analytically the phenolic parameters in the grape inside specialized laboratories inevitably limits the possibility of evaluating the phenolic ripeness in the field, namely directly in the vineyard.

[0010] An object of the invention is to improve the apparatuses and methods that are usable for analyzing the colour of a material or product.

[0011] Another object is to make available an apparatus and a method that enable a colour image of a sample of unhomogeneous material or product, in particular a colour image of a sample of material or product that is chromatically unhomogeneous, to be analyzed reliably and efficiently. [0012] A further object is to make available an apparatus and a method that enable physical and chemical parameters to be determined of a chromatically unhomogeneous sample through the analysis of colour images of the aforesaid sample.

[0013] A still further object is to make available an apparatus and a method that enable physical and chemical parameters to be determined that define the degree of phenolic ripeness of a grape sample directly in the field, namely in the vineyard, in a substantially rapid manner, without the need to use qualified personnel, costly instruments and chemical reagents to be disposed of suitably after use.

[0014] In a first aspect of the invention, an apparatus is provided for determining at least one physical parameter and/or at least one chemical parameter of a chromatically unhomogeneous sample, as defined in claim 1.

[0015] In a second aspect of the invention, a method is provided for determining at least one physical parameter and/or at least one chemical parameter of a chromatically unhomogeneous sample, as defined in claim 19.

[0016] Owing to these aspects, an apparatus and a method are made available that enable colour images to be acquired, in particular RGB digital images, of a sample of chromatically unhomogeneous material or product, the aforesaid images to be processed by a computerized mathematical procedure and physical and chemical parameters to be consequently determined that are linked to specific properties of the material or product.

[0017] Processing of the acquired images is the step of the method according to the invention that enables the information of interest correlated with the chromatic appearance (colour) of the sample to be extracted. More exactly, this processing step consists of the construction of a mathematical model, in particular a multivariate calibration model, that compares the values (measured in laboratory through known analytical methods) of physical and chemical parameters linked to the colour with the instrumentally acquired image of the sample. For example, in the case of the determination of the degree of phenolic ripeness of the grapes, the parameters of interest comprise the content of the various types of anthocyanins.

[0018] Following the same procedure that is commonly adopted, for example, in the NIR spectrophotometric analysis, the calibration models are then processed and validated by using a series of samples for which the values of the parameters of interest have been previously determined. The same calibration models are used to predict the values of the parameters of interest on new samples: for each new sample it is possible to acquire a corresponding colour image and, by applying the calibration model, obtain in real time an estimate of the (physical and chemical) properties of interest.

[0019] The method according to the invention can be implemented by using a smartphone of known type as an image acquisition device, in combination with the apparatus according to the invention. In fact, smartphones of known type are equipped with digital cameras that enable the examined sample to be evaluated with a spatial resolution equal to several million pixels. Consequently, it is possible to evaluate in a detailed manner chromatically unhomogeneous samples, since each of the different colours contained in the image of the sample is reproduced by one or more pixels.

[0020] As it will appear immediately understandable to a person skilled in the art, the method according to the invention can be suitably implemented also by using an image acquisition device other than the smartphones of known type, such as for example a digital camera that is not incorporated into a smartphone or a digital camera that is incorporated into a tablet of known type. Therefore, the image acquisition device that is usable in combination with the apparatus according to the invention for carrying out the method according to the invention is substantially a digital camera of known type, which may or may not be incorporated into devices of known type such as smartphones and tablets. The method according to the invention can be implemented in a code of a program that is runnable by a computer. The program can be stored in a support that is readable by a computer. Moreover, the program can be loaded or stored in the computer. The computer can be provided with, or be connected to, a digital camera. As it will be clear to a person skilled in the art, a computer provided with a digital camera corresponds, for example, to a smartphone or tablet of known type, whilst a computer connectable to a digital camera corresponds, for example, to a portable computer of known type.

[0021] The apparatus according to the invention has been designed for the purpose of controlling and making reproducible lighting conditions that are suitable for acquiring digital images (RGB) by the aforementioned digital camera. As it will be disclosed in detail below, the apparatus according to the invention is made in the form of an image acquisition chamber, in particular a controlled lighting image acquisition chamber, having a shape and dimensions such as to enable easy in situ conveying and use (portable image acquisition chamber).

[0022] After positioning the samples inside the image acquisition chamber according to the invention, it is possible to photograph the samples (for example, through the digital camera of a smartphone or tablet) and send the acquired digital images (for example, through a mobile application or app) to a remote server, in which the images are processed and the (previously constructed) calibration models are applied through the use of an algorithm (developed by the Inventors).

[0023] The algorithm exploits calibration models that are capable of comparing the chromatic appearance of the sample with physical and chemical parameters of the latter. For example, in case that the apparatus and the method according to the invention are used to determine the degree of phenolic ripeness of the grapes, the colour of the samples is analyzed to determine the amounts of different types of anthocyans and other chemical- physical parameters linked to ripening, of interest in the vine-growing / wine-making field.

[0024] The results of the processing of the acquired images (namely, the values of the colour parameters calculated on the acquired images) are sent directly from the server to the smartphone (or tablet) and are displayed on the screen of the latter in real time.

[0025] The apparatus and the method according to the invention can be used effectively for chromatically unhomogeneous products, namely for products the colour images of which cannot be suitably analyzed by using known colorimetric apparatuses and methods.

[0026] For example, the apparatus and the method according to the invention can be used for determining physical and chemical parameters defining the degree of phenolic ripeness of a grape sample directly in the field, namely in the vineyard, avoiding resorting to significantly costly and long laboratory analyses, as well as the consumption of chemical reagents that are substantially harmful and are thus to be suitably disposed of after use.

[0027] In fact, the apparatus and the method according to the invention enable the vine- grower to monitor autonomously the ripening curves of the grape, namely to determine the trend over time of different chemical parameters relating to the phenolic ripeness of the grape, without resorting to laboratory analyses. This in turn enables the costs required for the execution of chemical analyses at specialized laboratories, as well as the waiting times necessary for obtaining the analytical results, to be reduced. In particular, by using the apparatus and the method according to the invention, it is possible to quantify from 10 to 15 different analytical parameters (among which: total anthocyans content, total polyphenols content, intensity, tone and content of the main anthocyanidins) in an extremely short time, in particular a time of a few dozen seconds, and directly in the field.

[0028] In this manner, it is possible to increase the frequency and the number of the controls, even without the use of specialized personnel, so as to increase the production efficiency. Moreover, through the method and the apparatus according to the invention it is possible to identify areas of the vineyard in which the grapes have different degrees of phenolic ripeness, this permitting harvesting at different times in the different areas of the vineyard or separating the grapes suitably at the time of harvesting. This is particularly useful in the case of vineyards that are positioned in such a manner that different plants can benefit from a different exposure to the sun (for example, hillside vineyards) and thus a different ripening evolution.

[0029] It should be noted that all this can be obtained by the users (operators in the vine- wine sector such as vine-growers, oenologists, winery technicians) simply and rapidly, by using, for example, their own smartphone in combination with the image acquisition chamber according to the invention. In fact, once the grape samples have been photographed, the acquired data can be sent (for example, through app for smartphone) to the remote server, in which the images are processed and the calibration models are applied and from which the results of the processing of the acquired images are sent directly to the smartphone in an extremely short time (few dozen seconds). This procedure can be repeated several times, performing multiple determinations in different zones of a vineyard and in different ripening times, which enables a historical archive to be created of data that are easily consultable by the users.

[0030] It should further be noted that, although in many parts of the present description reference is made to a specific use of the apparatus and the method according to the invention (determination of the degree of phenolic ripeness in grapes), it is possible to use the apparatus and the method according to the invention in different fields and for different purposes, namely on materials or food products other than grapes (for example: determination of the degree of ripeness of other vegetable products; determination of the degree of roasting in coffee; determination of the degree of baking in baked products) or on non-food materials or products (for example, ceramic specimens).

[0031] The invention can be better understood and implemented with reference to the attached drawings that illustrate an embodiment thereof by way of non-limiting example, in which:

[0032] Figure 1 is a perspective schematic view of an apparatus according to the invention;

[0033] Figure 2 is a further perspective schematic view of the apparatus of Figure 1; [0034] Figure 3 is a perspective and partially sectioned schematic view of the apparatus of Figure 1;

[0035] Figure 4 is a perspective schematic view of a mobile element, which is comprised in the apparatus of Figure 1 and not shown in Figures 1-3;

[0036] Figure 5 is a perspective schematic view of a further movable element, which is comprised in the apparatus of Figure 1 and not shown in Figures 1-3;

[0037] Figure 6 is a plan schematic view of a colour reference panel, which is comprised in the apparatus of Figure 1 and not shown in Figures 1-3;

[0038] Figure 7 is a graph showing an example of a colourgram, namely a one dimensional signal describing the colour contents of an RGB digital image, which is usable in the method according to the invention.

[0039] In the present description, as well as in the attached claims, the definitions listed below apply.

The terms“sample” and“samples” refer to samples of products and materials and the latter can be food products and materials or non-food products and materials.

The terms“chromatically unhomogeneous sample” and“chromatically unhomogeneous samples” refer to samples of chromatically unhomogeneous products or materials.

The terms“chromatically unhomogeneous” and“chromatically unhomogeneous” refer both to samples of materials and products having a surface colouring that is unhomogeneous as a result of an unhomogeneous physical structure (for example, a material consisting of particles) and to samples of materials and products having a substantially homogeneous physical structure but exhibiting an unhomogeneous surface colouring (for example, a product that is made in the form of a compact slab, but is coloured irregularly).

The term“controlled lighting image acquisition chamber” defines an image acquisition chamber provided with fixed and/or movable walls and equipped internally with lighting means, in which the fixed and/or movable walls separate substantially the inside of the chamber from the external environment and from the ambient luminosity and the lighting means provides an inner lighting that is controlled, namely is not influenced by the external ambient luminosity.

The term“image acquisition device” refers to a known digital camera, which can be separate from, or incorporated into, a mobile electronic device, such as a smartphone or a tablet. The term “desktop-type application” defines a computer program or a plurality of computer programs that are installed or installable in a data management and processing electronic device, such as a server or a computer.

The term“mobile application” or“app” defines a computer program or a plurality of computer programs that are installed or installable in a mobile electronic device, such as a smartphone or a tablet.

The term“server” defines a data managing and processing electronic device, which performs service functions for other computers or mobile electronic devices, such as smartphone and tablets, which are connected or connectable thereto.

The terms“colourgram” and“colourgrams” define one-dimensional signals describing the colour contents of RGB digital images, obtained through a known algorithm.

[0040] Figures 1 to 5 show an apparatus 1 according to the invention, which is usable for acquiring a colour image (RGB digital image) of a sample of a chromatically unhomogeneous material or product. Through the analysis of the aforesaid image it is possible to determine at least one physical parameter and/or at least one chemical parameter of interest of the aforesaid chromatically unhomogeneous sample.

[0041] The apparatus 1 comprises a controlled lighting image acquisition chamber 2, in turn comprising a body 3, which is substantially parallelepipedon- shaped and internally hollow, a lid element 10 and a sample holder element 12. Both the lid element 10 and the sample holder element 12 are movable, in particular movable in a slidable manner, according to two reciprocally opposite and parallel directions Fl and F2 (indicated by corresponding arrows in Figure 3). The body 3, the lid element 10 and the sample holder element 12 are made of a suitable stiff, opaque and shock resistant material, for example a thermoplastic polymer material such as acrylonitrile -butadiene- styrene (ABS).

[0042] The body 3 is defined overall by a plurality of walls, comprising a base wall 4, a first end wall 5, a second end wall 6 (which, in the following of the description and in the attached claims, are also called“pair of end walls 5, 6” or“end walls 5, 6”), a first side wall 7 and a second side wall 8 (which, in the following of the description and in the attached claims, are also called“pair of side walls 7, 8” or“end walls 7, 8”). The base wall 4, the end walls 5, 6 and the side walls 7, 8 are rectangle-shaped. In one embodiment that is not shown, the body can be substantially cube-shaped and, in this case, the various walls are square-shaped. [0043] The first end wall 5 and the second end wall 6 are reciprocally opposite and parallel to one another, just like the first side wall 7 and the second side wall 8 are reciprocally opposite and parallel to one another. The end walls 5, 6 are arranged transversely to the side walls 7, 8. The end walls 5, 6 and the side walls 7, 8 are arranged transversely to the base wall 4. The plurality of walls of the body 3 (namely, the base wall 4, the end walls 5, 6 and the side walls 7, 8) overall defines an operating chamber 11, comprised in the controlled lighting image acquisition chamber 2.

[0044] The sides of the end walls 5, 6 and of the side walls 7, 8 that are opposite, namely non adjacent, to the base wall 4 comprise corresponding free edges 5a, 6a, 7a and 8a. The free edges 5a-8a are substantially rectilinear and overall define an opening 9, which is opposite the base wall 4 and has a substantially rectangular shape. The opening 9 is arranged for receiving the lid element 10 (that will be disclosed in detail below). After partially or totally removing the lid element 10, an operator can access the operating chamber 11 through the opening 9 and carry out, or example, maintenance and/or cleaning interventions.

[0045] In the first end wall 5, near the adjacent base wall 4, an inlet and outlet opening 14 is made, which is substantially rectangle- shaped and is arranged transversely. In particular, the inlet and outlet opening 14 extends parallel to the free edge 5 a and parallel to an adjacent side of the base wall 4. The dimensions of the inlet and outlet opening 14 are selected in such a manner as to enable the sample holder element 12 (that will be disclosed in detail below) to be easily and rapidly inserted into, and extracted from, the body 3 of the controlled lighting image acquisition chamber 2. In an inner face of the first end wall 5, near the free edge 5a, a groove 5d (Figure 2; Figure 3) is obtained that extends parallel to the free edge 5 a.

[0046] In the second end wall 6, which is parallel to and opposite the first end wall 5, a rectilinear inlet and outlet cut 15, most of which corresponds to the free edge 6a, and a transit opening 16, arranged for enabling the passage of electric power cables (not shown), are obtained.

[0047] The inlet and outlet cut 15 extends substantially parallel to the base wall 4 of the body 3 and is made in such a manner as to define (in the second end wall 6) two end portions 6b, 6c (Figure 2), positioned at opposite ends of the inlet and outlet cut 15 (and of the free edge 6a). Each of the two end portions 6b, 6c is approximately L-shaped (Figure 2). [0048] The transit opening 16 is made near the inlet and outlet cut 15, in a zone of the second end wall 6 comprised between the inlet and outlet cut 15 and the second side wall 8. The transit opening 16 is made in the form of a through hole, for example a through hole having a substantially rectangular cross section. In embodiments that are not shown, the through hole can have a non-rectangular cross section, for example a square, round, elliptic or rhomboidal cross section.

[0049] The second end wall 6 further comprises, near the base wall 4, an electric supply zone 6d, to which a battery 17 of known type (shown schematically with a dashed line in Figure 2) is fixed. The battery 17 is fixed removably through mechanical fixing means of known type (not shown), for example snap fit elements or screws. The battery 17 can be a rechargeable battery, for example a“power-bank” battery with lithium ions with polymeric electrolyte, having a 5,000 mAh (milliamp/hour) or higher capacity. As shown in Figure 2, the electric supply zone 6d is comprised in an external face of the second end wall 6 and the battery 17 is thus installed outside the body 3. From the battery 17 the electric power cables lead away that enter the operating chamber 11 through the transit opening 16.

[0050] In embodiments that are not shown, the battery can be installed in different zones of the body, for example on the first end wall or on one of the two side walls. In other embodiments that are not shown, the battery may not be installed on the outer surface of the body and may thus be connected to the latter only through the electric power cables.

[0051] In inner faces of the first side wall 7 and of the second side wall 8, near respectively the free edge 7a and the free edge 8a, grooves 7d and 8d are obtained that extend parallel to the respective free edges 7a and 8a. Overall, the groove 5d (of the first end wall 5) and the two grooves 7d and 8d define a grooved seat 18 (Figure 2) of the body 3, which seat has an approximately U-shaped plan form (with concavity facing the second end wall 6) and is arranged for receiving slidingly - alternatively according to the direction Fl or F2 - the lid element 10. Moreover, still in the inner faces of the first side wall 7 and of the second side wall 8, near the base wall 4, two longitudinal guides 7e (Figure 3) and 8e (Figure 1) are comprised, each of which is made in the form of an elongated element protruding from the corresponding side wall 7, 8 and extending parallel to the base wall 4. As shown in Figure 3 (in which the body 3 devoid of the second side wall 8 is visible) relatively to the longitudinal guide 7e, each of the longitudinal guides 7e, 8e extends between the inlet and outlet opening 14 and an abutment element 20. More exactly, each of the longitudinal guides 7e, 8e starts near the inlet and outlet opening 14 and ends near an abutment wall 22 of the abutment element 20.

[0052] In embodiments that are not shown, only one of the two longitudinal guides is present or each of the side walls is provided with more than one longitudinal guide. In other embodiments that are not shown, the side walls are devoid of longitudinal guides. In further embodiments that are not shown, the outer faces of the side walls are provided with grips (for example, handles or knobs) to facilitate the manual handling of the apparatus.

[0053] The abutment element 20 protrudes from the base wall 4 and comprises a supporting wall 21 and the abutment wall 22, arranged transversely to one another and connected reciprocally. The abutment wall 22 is arranged parallel to the first end wall 5 and has dimensions that are almost the same as those of the inlet and outlet opening 14, whilst the supporting wall 21 is arranged parallel to the base wall 4. The abutment element 20 bounds a housing 13 of the sample holder element 12 and supports a colour reference panel 40, shown in Figure 6. The housing 13 is arranged for receiving slidingly the sample holder element 12.

[0054] The colour reference panel 40 is made, for example, of a paper and/or plasticized material, is rectangle-shaped and has dimensions substantially corresponding to those of the supporting wall 21. As it will be explained in greater detail below, the colour reference panel 40 is used in the apparatus and in the method according to the invention for correcting the acquired images in the controlled lighting image acquisition chamber 2.

[0055] The colour reference panel 40 comprises a plurality of colour references 40a, made in the shape of coloured quadrilaterals having the same dimensions and arranged in adjacent rows. In particular, in the colour reference panel 40 the plurality of colour references 40a comprises six colour references (coloured quadrilaterals) 41 - 46, the positions of which in the panel, the tones of which and the colour formulas of which according to the RGB system are shown (with reference to Figure 6) in the following Table 1:

[0056] Table 1

[0057] The colour reference panel 40 of Figure 6 is usable in the apparatus 1, for example, to determine the degree of phenolic ripeness of the grapes through the method according to the invention. However, as it will appear clear to a person skilled in the art, it is possible to modify suitably the number, the position and/or the colour tones of the colour references on the basis of the type of colour image to be acquired, corrected and processed, namely on the basis of the scope of the apparatus and of the method according to the invention.

[0058] The operating chamber 11 comprises the housing 13 (Figure 3), which is substantially shapingly coupled with the sample holder element 12 and is arranged for receiving the latter slidingly. The housing 13 is defined overall by: an inner face 4a of the base wall 4, comprised between the inlet and outlet opening 14 and the abutment wall 22 of the abutment element 20; the abutment wall 22; portions of inner faces of the first side wall 7 and of the second side wall 8, adjacent to the inner face 4a and comprising the longitudinal guides 7e, 8e. The housing 13 communicates with the outside, through the inlet and outlet opening 14 (that is parallel to and opposite the abutment wall 22), and with the remaining portion of the operating chamber 11.

[0059] The controlled lighting image acquisition chamber 2 is equipped with, namely comprises, lighting means 19 (shown in Figure 3 and represented schematically with a dashed line). The lighting means 19 is installed in the inner faces of the end walls 5, 6 and of the side walls 7, 8 near the grooved seat 18 and the inlet and outlet cut 15. The lighting means 19 is of known type and can comprise, for example, a LED (SMD 3528 LED 5V USB, 6500 K colour temperature) strip, namely a flexible strip comprising a plurality of LED-type lighting elements. The lighting means 19 is inserted into housing grooves (not shown) obtained in the inner faces of the end walls 5, 6 and of the side walls 7, 8, or are fixed removably to the aforesaid inner faces through mechanical fixing means of known type (not shown), for example snap fit elements or screws. The lighting means 19 is supplied electrically by the battery 17 through the electric power cables, which come from the electric supply zone 6d (and thus from the battery 17) and enter the operating chamber 11 through the transit opening 16.

[0060] In one embodiment that is not shown, the apparatus according to the invention can be connected (by cable) to a power supply of known type and the latter can be used alternatively to the battery. In other embodiments that are not shown, the lighting means can be installed in the inner faces of the side walls in positions spaced away from the grooved seat and/or from the inlet and outlet cut. In further embodiments that are not shown, the lighting means can be installed alone or on some of the inner faces of the side walls or of the end walls.

[0061] The sample holder element 12 (Figure 4) is made substantially in the shape of a drawer, having a substantially rectangular plan shape and comprising a containing portion l2a and a gripping portion l2b, defining overall a sample holder cavity l2c. In one embodiment that is not shown, in which the body of the apparatus according to the invention is substantially cubical, the sample holder element is made in the form of a drawer having a square plane shape.

[0062] The containing portion l2a comprises a pair of side walls 23, 24, a bottom wall 25 and an end wall 26. The two side walls 23, 24 are reciprocally parallel and opposite and are arranged transversely to the bottom wall 25 and to the end wall 26. In each of the two side walls 23, 24 a guiding groove 23a, 24a is obtained (only the guiding groove 24a of which is shown in Figure 4), arranged for being received slidingly - alternatively according to the direction Fl or F2 - with the corresponding longitudinal guide 7e, 8e of the first side wall 7 and of the second side wall 8.

[0063] In embodiments that are not shown, only one of the two guide grooves is present or each of the side walls is provided with more than one guide groove. In other embodiments that are not shown, the side walls are devoid of guide grooves.

[0064] The gripping portion l2b is parallel to and opposite the end wall 26 and is made in the form of a rectangular plate, comprising a front face l2d. The gripping portion l2b has a greater transverse dimension (width) and a lesser transverse dimension (height) that are respectively greater than the greater transverse dimension (height) and the lesser transverse dimension (height) of the inlet and outlet opening 14. Consequently, when the sample holder element 12 is completely inserted into the housing 13 of the operating chamber 11, a peripheral abutment portion l2e of the gripping portion l2b is juxtaposed on the first end wall 5 and is graspable by an operator to extract the sample holder element 12 from the housing 13. Moreover, when the sample holder element 12 is completely inserted into the housing 13 of the operating chamber 11, the end wall 26 of the containing portion l2a is juxtaposed on the abutment wall 22 of the abutment element 20. [0065] From what has been disclosed above, it is clear that the sample holder cavity l2c is defined overall by: the bottom wall 25, the two side walls 23 and 24, the end wall 26 and a face (not shown) of the gripping portion l2b opposite the front face l2d and facing the end wall 26.

[0066] In one embodiment that is not shown, the gripping portion has the same dimensions as those of the inlet and outlet opening, thus not comprising the peripheral abutment portion, and the front face of the gripping portion is provided with a grip, for example a handle or a knob, to enable the sample holder element to be extracted from the housing. In another embodiment that is not shown, the gripping portion is provided with both the peripheral abutment portion and the grip.

[0067] The lid element 10 (Figure 5) acts substantially as a movable lid of the controlled lighting image acquisition chamber 2 and is shaped in the form of a rectangular plate, having a greater transverse dimension (length) that is longer than the corresponding greater transverse dimension (length) of the body 3. In one embodiment that is not shown, the greater transverse dimensions (lengths) of the lid element and of the body are the same. The lid element 10 comprises an abutment end lOa and a housing portion lOb, extending over most of the greater transverse dimension of the lid element 10. The housing portion lOb (substantially suitable for receiving a smartphone) is defined by a frame element lOc, approximately U-shaped (with concavity opposite the abutment end lOa). The frame element lOc comprises an intermediate segment lOe and two lateral segments lOf, lOg, the intermediate segment lOe of which is interposed transversely to the two lateral segments lOf, lOg, which are reciprocally parallel. Each segment lOe-lOg has an approximately L- shaped cross section (Figure 5), so as to enable an image acquisition device having a substantially flat shape, such as for example a smartphone, to be inserted and positioned suitably in the housing portion lOb. A quadrilateral- shaped window lOi is comprised in the housing portion lOb. The window lOi is made as a through hole, near the intermediate segment lOe of the frame element lOc. Through the window lOi, the housing portion lOb is put in communication with the operating chamber 11 when the lid element 10 closes superiorly the controlled lighting image acquisition chamber 2.

[0068] As it will appear clear to a person skilled in the art, the shape and the dimensions of the window lOi, as well as the zone of the housing portion lOb in which the window lOi is obtained, can be modified and suitably selected on the basis of the type of image acquisition device to be used in combination with the apparatus 1. Consequently, in embodiments that are not shown of the apparatus according to the invention, the window can be made in a central zone of the housing portion or at an end of the housing portion that is opposite the intermediate segment of the frame element. Further, the window can have a different shape from the shape disclosed above and can be, for example, oval or round.

[0069] The abutment end lOa and the housing portion lOb are surrounded by an edge portion lOd, shapingly coupled with the grooved seat 18 and with the inlet and outlet cut 15. In this manner, an operator can insert manually the lid element 10 through the inlet and outlet cut 15 and slide the edge portion lOd in the grooved seat 18, alternatively according to the direction Fl or F2, so as to close or open the operating chamber 11. In particular, by moving the lid element 10 according to the direction Fl until the abutment end lOa is brought into contact with the first end wall 5, it is possible to close the operating chamber 11 and achieve inside the latter, through the lighting means 19, optimum conditions of controlled lighting.

[0070] The housing portion lOb is arranged for receiving and maintaining suitably in position an image acquisition device (not shown) of known type, for example a smartphone. The latter can be inserted into the housing portion lOb, in such a manner that the digital camera of the smartphone faces the window lOi, and slid into the frame element lOc until an end thereof is made to abut on the intermediate segment lOe. When the lid element 10 has been inserted into the operating chamber 11, through the inlet and outlet cut 15, and slid completely into the grooved seat 18 so as to close the operating chamber 11, the smartphone can be used to acquire colour images of a desired sample inserted inside the operating chamber 11 through the sample holder element 12.

[0071] On the basis of what has been disclosed, in the apparatus 1, and thus in the controlled lighting image acquisition chamber 2, it is possible to identify: a sample insertion and removal portion 2a, substantially corresponding to, and thus comprising, the sample holder element 12 and the housing 13 of the operating chamber 11; an image acquisition portion 2b, substantially corresponding to, and thus comprising, the lid element 10 and the operating chamber portion 11 comprised between the housing 13 and the lid element 10.

[0072] In use, the apparatus 1 is so positioned that the base wall 4 is in contact with a resting surface (not shown), that can be, for example, a portion of table, floor or ground. For example, when the apparatus 1 is used to determine the degree of phenolic ripeness of the grapes, the resting surface can comprise a portion of the ground of a vineyard. In this position, the base wall 4, the lid element 10 and the containing portion l2a of the sample holder element 12 are parallel to the resting surface, namely are substantially horizontal if the resting surface is horizontal, whilst the end walls 5, 6 and the side walls 5-8 are arranged transversely to the resting surface, namely are substantially vertical if the resting surface is horizontal.

[0073] In the position of the apparatus 1 disclosed above, to use the apparatus 1 the operator positions himself or herself opposite, or to the side of, the first end face 5, so as to be able to move manually the sample holder element 12 and the lid element 10. The operator slides the lid element 10 into the grooved seat 18 according to the direction Fl to close the opening 9, namely to close (superiorly) the operating chamber 11 and slides the lid element 10 into the grooved seat 18 according to the direction F2 to make the operating chamber 11 accessible, namely to open the operating chamber 11. The operator slides the sample holder element 12 in the housing 13 according to the direction F2 (namely towards the inside of the body 3) to insert a sample (previously positioned in the sample holder cavity l2c) into the operating chamber 11 and slides the sample holder element 12 in the housing 13 according to the direction Fl (namely towards the outside of the body 3) to remove the sample from the operating chamber 11.

[0074] Although the configuration of the housing portion lOb shown in Figure 5 is particularly suitable for housing a smartphone, a person skilled in the art is easily able to modify the aforesaid configuration to enable other known types of image acquisition devices to be housed, such as for example a tablet or a digital camera. For example, it is possible to modify the dimensions of the frame element lOc and/or vary the shape or the dimensions of the segments lOe-lOg so as to enable an image acquisition device, other than a smartphone, to be received in the housing portion lOb.

[0075] The body 3 is shaped and sized in such a manner that the distance between the lens of the image acquisition device (smartphone, tablet or digital camera) and the bottom wall 25 of the sample holder element 12 (and thus between the sample and the lens) enables the images of the sample to be suitably focused. The body 3 is furthermore shaped and sized in such a manner that, when the operating chamber 11 is closed completely (from above) by the lid element 10, the sample holder element 12 is completely inserted into the housing 13 and the image acquisition device is suitably positioned in the housing portion lOb, the field of the image that is acquirable by the device includes only the sample contained in the sample holder element 12 and the colour reference panel 40.

[0076] In order to exemplify the dimensions that the apparatus according to the invention may have and with reference to the embodiment of the apparatus 1 shown in Figures 1-5, in the following Table 2 some dimensions are shown relating to the body 3, the lid element 10 and the sample holder element 12:

[0077] Table 2

[0078] It should be noted that the dimensions shown in Table 2 relate to an embodiment of the apparatus 1 that is usable in combination with a specific image acquisition device, namely an LG G4 (Processor 1.8 GHZ 6 Core, Ram 3 GB, 16 Megapixels) smartphone. However, a person skilled in the art is clearly and easily able to modify the dimensions in Table 2 above, in function of the type of image acquisition device to be used in combination with the apparatus 1.

[0079] For example, Table 2 shows that the greater transverse dimension (length) of the body is less than the corresponding greater transverse dimension (length) of the lid element (160 mm versus 206.7 mm). This is necessary in order to position correctly the lens of the digital camera of the LG G4 smartphone with respect to the window lOi and thus with respect to the sample insertion and removal portion 2a of the controlled lighting image acquisition chamber 2. It is however clear that, by using an image acquisition device that is different (for example, dimensionally different) from the aforesaid smartphone model, the lens of the image acquisition device can be correctly positioned even in an embodiment of the apparatus 1 in which the body and the lid element have the same greater transverse dimension (length). [0080] It should be noted that, in order to implement the method according to the invention effectively, it is necessary to be able to make use of a controlled and constant lighting. This implies that, in images acquired from different samples, possible colour differences must be due only to different physical and chemical properties of the samples, and not to different conditions of luminosity in the step of acquisition of the images. The apparatus 1 according to the invention meets this requirement effectively, inasmuch as it enables lighting of the sample to be controlled completely, excluding the variability connected to the natural ambient light. Moreover, owing to the colour reference panel 40, incorporated in the apparatus 1 and used in the method according to the invention to correct the acquired RGB images (as it will be explained in greater detail below), it is possible to compensate effectively possible variations in the artificial lighting conditions inside the apparatus 1. These possible variations can be caused, for example, by anomalous operation and/or aging phenomena of the lighting means 19.

[0081] The method according to the invention is a method for determining at least one physical parameter and/or at least one chemical parameter of interest in a sample of chromatically unhomogeneous material or product through acquisition and processing of colour images of the sample. In the method according to the invention it is possible to identify the following main steps:

a) Acquiring through an image acquisition device an RGB digital image of the sample, placed inside a controlled lighting image acquisition chamber (namely placed inside the apparatus 1 according to the invention);

b) Processing the acquired RGB digital image, namely correcting the acquired image, converting through algorithm the acquired and corrected image into a corresponding one dimensional signal (colourgram) describing the colour contents of the image (namely encoding the information relating to the colour of the image), applying a multivariate calibration model, namely comparing the one-dimensional signal with a specific multivariate calibration model for the at least one physical parameter and/or the at least one chemical parameter of interest, and obtaining through this comparison estimated values of these parameters.

[0082] The multivariate calibration model to be used varies according to the physical or chemical parameter of interest and can be generated through a procedure comprising the following steps: - Acquiring (through the use of the apparatus 1) a plurality of RGB digital images from a corresponding plurality of samples of a (chromatically unhomogeneous) product or material of interest;

- Analyzing the samples, the images of which have been acquired, by using known analytic methods and apparatuses, so as to determine the values of the at least one physical parameter and/or of the at least one chemical parameter of interest;

- Processing the plurality of acquired RGB digital images, namely correcting the acquired images, and converting through algorithm the corrected images into a corresponding plurality of one-dimensional signals (colourgrams) describing the colour contents of the plurality of images;

- Correlating mathematically the plurality of one-dimensional signals with the values of the at least one physical parameter and/or of the at least one chemical parameter of interest that have been determined analytically, so as to obtain the multivariate calibration model.

[0083] The various steps of the method according to the invention are disclosed below, with particular reference to the manner in which the apparatus 1 according to the invention is used in combination with an image acquisition device of known type, namely a smartphone.

[0084] It should be noted that, although the use of a smartphone has been disclosed by way of example, the person skilled in the art can use another suitable image acquisition device, for example digital camera or tablet, by adapting or modifying appropriately the previously disclosed apparatus 1.

[0085] The smartphone is switched on and inserted (by the operator) into the housing portion lOb of the lid element 10, in such a manner that the digital camera of the smartphone faces the window lOi. The lid element 10 is then moved (in particular, moved slidingly) manually into the grooved seat 18 of the body 3 according to the direction Fl, so as to close the operating chamber 11 above.

[0086] Alternatively, the operator can first insert the lid element 10 into the body 3 and subsequently insert the smartphone into the housing portion lOb.

[0087] The sample holder element 12 is opened, namely moved (in particular, moved slidingly) manually into the housing 13 according to the direction Fl, and a sample of chromatically unhomogeneous material or product to be analyzed (for example, a sample consisting of grape berries whose degree of phenolic ripeness it is desired to determine) is placed in the sample holder cavity l2c. The sample holder element 12 is then closed, namely moved (in particular, moved slidingly) into the housing 13 according to the direction F2.

[0088] Alternatively, the operator can extract completely the sample holder element 12 from the body 3, insert the sample into the sample holder cavity l2c and then insert again the sample holder element 12 into the body 3.

[0089] By inserting completely the lid element 10 and the sample holder element 12 into the body 3 of the controlled luminosity image acquisition chamber 2, the operating chamber 11 is separated from the external environment and thus from the ambient luminosity. It is thus possible to switch on the lighting means 19 and make inside the operating chamber 11 luminosity conditions that are suitable for acquiring images of the sample by the smartphone.

[0090] The operator starts a mobile application (or app), which was previously installed on the smartphone and enables an RGB digital image (colour photograph) to be acquired of the sample and the data relating to the acquired image, or input data, to be sent to a remote server, at which the data are processed. In the remote server a program is installed that enables the data relating to the acquired image to be received and processed, namely: correcting the image, converting through algorithm the image into a colourgram, applying the multivariate calibration model that is adapted for the type of sample and specific for the physical and chemical parameters of interest, obtaining through this comparison estimated values of the aforesaid parameters. The dispatch of the data can take place by using known procedures, namely by a connection to a mobile data network or a connection to a wireless data network. The input data sent to the server can also comprise the time and date of the sampling, namely time and date in which the images were acquired, as well as data for geolocalizing the sampling site (GPS coordinates).

[0091] In one embodiment of the method, the apparatus 1 is used in combination with an image acquisition device other than the smartphone, in particular a tablet, the mobile application can be installed in the tablet and the digital camera of the latter can be used to acquire images of the sample. The data can be sent to the server by connecting the tablet to a mobile data network or a wireless data network.

[0092] In another embodiment of the method, the apparatus 1 is used in combination with a digital camera that is not incorporated into a mobile electronic device (smartphone or tablet). The digital camera can be connected through cabled connection to a computer, in particular a portable computer, which can in turn send the data to be processed to the server, for example by using a connection to a wireless network of known type. In this embodiment of the method, in the portable computer a desktop-type application is installed that is equivalent to the mobile application for smartphones or tablets and is usable for managing operation of the digital camera through the portable computer.

[0093] In a further embodiment of the method, the data relating to the acquired image are processed directly in the image acquisition device. This can be obtained by using a smartphone or a tablet, in which both the mobile application for acquiring the images and the program for processing the data relating to the acquired image are installed. Similarly, if the digital camera is used that is not incorporated into a mobile electronic device and is connected to a computer, the desktop-type application for acquiring the images and the program for processing the data on the acquired image are installed in the computer.

[0094] In this manner, it is possible to acquire the RGB images of the samples and process the images directly on the image acquisition device, eliminating or minimizing the wait time between the dispatch of the input data to the server and the receipt of the output data from the server. Moreover, processing the images directly on the image acquisition device is useful if the operator is using the apparatus and the method according to the invention in the field (for example, to determine the degree of phenolic ripeness of the grapes) and the wireless network is not suitably accessible (intermittent, slow, limited or absent wireless connection) in the zone in which the operator is located (for example, a vineyard). The so acquired and processed images and the obtained results (values of the physical and/or chemical parameters of interest) can be downloaded at a later time onto a storage server, to which the image acquisition device can be connected through a cabled or wireless connection.

[0095] In the remote server (or on the smartphone or tablet), the RGB digital image of the sample is processed. The first processing step consists of the correction of the image, which is substantially a calibration procedure required for the purpose of minimizing possible variations, due for example to variations of the image acquisition device, and is performed on the basis of the plurality of colour references comprised in the colour reference panel that is positioned in the operating chamber of the apparatus according to the invention. In particular, if the colour reference panel 40 of Figure 6 is used, the plurality of colour references 40a will comprise six colour references 41 - 46.

[0096] A first step of the correction procedure consists of selecting the m colour references (coloured quadrilaterals) included in the colour reference panel. After which, each selected colour reference is subdivided into n groups of pixels, so as to take into account a possible spatial variability included in the coloured quadrilaterals. For each group of pixels, the median values of the RGB (Red, Green and Blue) colour channels are calculated and the median values are stored in a matrix. The latter has dimensions equal to {(m x n), 3}, where m is the number of selected areas, n is the number of groups of pixels and 3 is the number of RGB colour channels.

[0097] For each colour channel (c), a regression model is calculated between the median vector (namely the numeric vector having dimensions equal to {(m x n), 1 }, which corresponds to the column of the aforesaid matrix of the median values relating to the colour channel c) extracted from a standard image of the colour reference panel taken as a master (M) and the corresponding median vector (namely the median vector relating to the colour channel c) of the colour reference panel of the acquired image (A) in the apparatus 1, according to the following equation (1):

M (c) = bo (c) + bi (c) x A (c) + b₂ (c) x A² (c) ... + b_x (c) x A^x(c) (1) in which bo, bi, b_{2. . .}b_x are the regression coefficients of the polynomial of degree x calculated for the colour channel c.

[0098] The regression coefficients calculated from the colour references are used to standardize each pixel of the acquired image, according to the following equation (2): imgco _r (i, c) = b₀ (c) + bi (c) x imgo_rig (i, c) + b₂ (c) x [imgo_rig (i, c)]²...+ b_x (c) x [img_0rig (i, c)]^x (2) wherein:

img_corr (i, c) is the i-th pixel of the colour channel c of the corrected image,

img_orig (i, c) is the corresponding i-th pixel of the colour channel c of the original image, bo, bi, b_{2. .} b_x are the regression coefficients calculated by the equation (1).

The degree x of the polynomial is defined on the basis of the statistical significance of the coefficients b.

[0099] The corrected image is then converted into a one-dimensional signal describing the colour contents of the image (colourgram) through an algorithm (disclosed in detail in Example 1). The algorithm for creating the colourgrams essentially consists of the calculation of the frequency distribution curves of a series of parameters relating to the colour, extracted from each RGB image. The frequency distribution curves are then joined in sequence and to them further statistical parameters are added, which derived from models based on the principal component analysis (PCA), calculated on the RGB image. In this manner, the three-dimensional data matrix corresponding to the RGB image, having dimensions {r, c, 3} (where r is the number of pixel rows, c is the number of pixel columns and 3 is the number of channels, namely the R, G and B values of each pixel) is reduced to a one-dimensional signal (colourgram) with dimensions { l x 4900}. Therefore, given a series of n images, a corresponding matrix of colourgrams is obtained with dimensions {n x 4900}, which can be then analyzed by appropriate multivariate analysis techniques.

[0100] After converting the acquired image into the corresponding one-dimensional signal describing the colour contents of the image, a multivariate calibration model (processed according to the procedure disclosed previously) is applied that is able to provide the value of the chemical or physical parameter of interest of the sample under examination.

[0101] For example, if the apparatus and the method according to the invention are used to determine the degree of phenolic ripeness of grapes belonging to a specific variety (vine), the multivariate calibration model will be used that is obtained from grape samples of the aforesaid variety. The physical parameters of the grape that are measurable by the apparatus and the method according to the invention comprise: intensity and tone (of the colour), optical densities at 420 nm, 520 nm and 620 nm, red purity. The chemical parameters of the grape that are measurable by the apparatus and the method according to the invention comprise: anthocyanidins (delphinidin-3-glucoside, cyanidin-3-glucoside, petunidin-3-glucoside, peonidin-3-glucoside, malvidin-3-glucoside, malvidin-3-acetyl glucoside, malvidin-3-cumaroilglucoside), total flavonoids and total anthocyans.

[0102] The data produced in the server and relating to the chemical or physical parameter of interest, or output data, are sent (through mobile network or wireless network) to the mobile image acquisition device or to the portable computer connected to the digital camera and displayed on the screen through the mobile application (on the screen of the smartphone or tablet) or the desktop application (on the screen of the portable computer connected to the digital camera). The processing of the data relating to the images (input data) and the production and dispatch of the results (output data) to the operator take place in an extremely short time. As disclosed previously, in one embodiment of the method according to the invention it is possible to process the data on the acquired image directly in the image acquisition device (in case of use of a smartphone or tablet) or in the portable computer connected to the image acquisition device (digital camera).

[0103] The output data (physical and chemical parameters of interest) can be displayed on the screen both in table format and map format. The displayed map shows the sampling sites and the spatial distribution of the measured values, namely the measured values for the physical and chemical parameters of interest in the different sampling sites. In the spatial distribution the values of the parameters can be indicated by numbers or chromatic scales. The data of the acquired physical and chemical parameters of interest, in addition to being displayed in almost real time by the operator, can be stored in the server, so as to create an archive of data that are consultable remotely even after time has elapsed and are usable for further investigations or controls.

[0104] For example, if the apparatus and the method according to the invention are used to determine the degree of phenolic ripeness of the grapes, operators of the vine-growing and wine-making sector, by entering the server remotely, can display and compare the results of samplings conducted on different vineyards, vintages and varieties of grape.

[0105] By way of exemplifying the invention, but without thereby limiting the scope of application and implementation of the invention, the following are disclosed: an algorithm that is usable in the method according to the invention to generate colourgrams from RGB digital images acquired from samples (Example 1); results of calibration models usable to determine the degree of phenolic ripeness of the grapes through the apparatus and the method according to the invention (Example 2); application of the method and of the apparatus according to the invention to evaluate the degree of roasting in samples of roasted coffee (Example 3).

[0106] Example 1 - Algorithm usable for generating colourgrams from RGB digital images acquired from samples

[0107] The algorithm used in the method according to the invention for processing the RGB digital images acquired through the apparatus according to the invention was developed by the Inventors and published for the first time in: A. Antonelli, M. Cocchi, P. Fava, G. Foca, G.C. Franchini, D. Manzini, A. Ulrici, Automated Evaluation of Food Colour by Means of Multivariate Image Analysis Coupled to a Wavelet-Based Classification Algorithm , Anal. Chim. Acta, 2004, 515, 3-13. Accordingly, in addition to the following description, and which is sufficiently clear and complete to enable a person skilled in the art to understand the use of the algorithm in the method according to the invention, possible further details on the algorithm are made available in the aforesaid publication.

[0108] The algorithm has been designed to extract from the RGB image information on physical and chemical parameters, expressing specific properties of the sample and which can be correlated with the chromatic appearance of the latter. For example, if the method according to the invention is used to determine the degree of phenolic ripeness of the grapes, the parameters of interest comprise, in particular, the contents in total anthocyans and polyphenols, the contents of the main anthocyanidins, intensity and tone of the colour. However, it should be pointed out that the use of the algorithm in the method according to the invention is independent of the analyzed material or product, as the most significant variables for obtaining information on the analyzed samples are selected automatically, without a priori hypotheses based on the nature of the sample under examination.

[0109] The algorithm converts an image (acquired, for example, trough the apparatus according to the invention) in a one-dimensional signal, named colourgram by the inventors. The colourgram can be considered as a“fingerprint” of the colour of the acquired image and thus of the considered sample. The colourgram enables the chromatic appearance (colour) of the sample to be quantified objectively, codifying all the aspects thereof that are visible in the image.

[0110] It should be noted that it is possible to apply to the colourgrams other known algorithms that perform a selection of variables, such as for example: iPLS (L. Nprgaard, A. Saudland, J. Wagner, I.P. Nielsen, L. Munck, S.B. Engelsen, Interval partial least- squares regression (iPLS): a comparative chemometric study with an example from near- infrared spectroscopy, Appl. Spectrosc., 2000, 54, 413-419), GA-PLS (R. Leardi, Application of genetic algorithm PLS for feature selection in spectral data sets, J. Chemom., 2000, 14, 643-655), WPTER (M. Cocchi, R. Seeber, A. Ulrici, WPTER: wavelet packet transform for efficient pattern recognition of signals, Chemom. Intell. Lab. Syst., 2001, 57, 97-119), WILMA (M. Cocchi, R. Seeber, A. Ulrici, Multivariate calibration of analytical signals by WILMA (Wavelet Interface to Linear Modelling Analysis), J. Chemom., 2003, 17, 512-527), sPLS-DA (K.A. Le Cao, S. Boitard, P. Besse, Sparse PLS discriminant analysis: biologically relevant feature selection and graphical displays for multiclass problems, BMC bioinformatics, 2011, 12, 253-269).

[0111] Through the selection of variables made by the aforesaid algorithms (or by other algorithms with similar functions), it is possible to extract a limited number of significant variables for each parameter (physical or chemical) under examination, enabling one or more parameters of interest to be evaluated in an extremely rapid and accurate manner. This enables the apparatus and the method according to the invention to be used in situ and results to be obtained substantially in real time. [0112] In the RGB digital images, each pixel is defined by the intensity values of three colour channels: red (R, a l ~ 630 nm), green (G, a l ~ 545 nm) and blue (B, a l ~ 435 nm). The wavelengths l indicated above correspond approximately to the spectral response of the human eye. It should be pointed out that when reference is made to an RGB image also all the colour spaces are implicitly understood that may derive from the RGB space, like the HSI system (Hue, Saturation and Intensity). Whilst the RGB code is generally used to acquire and display the images, the HSI system is more representative of the manner in which human beings perceive colours and is sometimes suitably used also for processing images.

[0113] The algorithm that enables RGB digital images to be converted into the corresponding colourgrams was written in an environment for the numeric calculation and statistical analysis of known type, namely MATLAB, and comprises the steps disclosed below.

[0114] The RGB image (acquired by using the apparatus 1 according to the invention and corrected according to the procedure disclosed previously) can be considered as a three- dimensional data matrix having dimensions {r, c, 3], where r is the number of pixel rows, c is the number of pixel columns and 3 is the number of channels, namely the R, G and B values of each pixel.

[0115] The three-dimensional matrix is converted into a two-dimensional matrix of dimensions {(r x c), 3], which shows the pixels in the rows and the R, G and B channels in the columns.

[0116] The two-dimensional matrix is extended by adding a series of columns, corresponding to the parameters calculated for each pixel from the R, G and B values. In particular:

- column 4 shows the Luminosity (L) values, namely the sum of the R + G + B values of each pixel;

- columns 5-7 show the ratios between each channel (R, G, B) and L (luminosity), which are defined as“relative colours”: relative red (rR), relative green (rG) and relative blue (rB);

- columns 8-10 show the hue (H), saturation (S) and intensity (I) values obtained by converting the RGB data into the HSI colour space by a suitable conversion function (of known type). [0117] After the aforesaid steps, the two-dimensional matrix reaches dimensions equal to {(r x c), 10} and is further extended by exploiting an alternative representation of the acquired image, which is obtained by projecting the RGB values of the original image into the space of the principal components. This procedure represents a transformation into an alternative chromatic space.

[0118] In particular, a statistical technique of known type is used, namely the Principal Components Analysis (PCA), which is applied to the two-dimensional RGB matrix so as to obtain three models: a first model (PCA_RAW) is calculated on raw (namely non pre treated) data, a second model (PCA_MNCN) is calculated on the data that are centred with respect to the mean and a third model (PCA_AUTO) is calculated on the self-scaled data. As the number of variables of the matrix is equal to 3, each PCA model will have 3 main components.

[0119] The two-dimensional matrix is then extended by adding the following columns:

- the columns 11-13 show the three vectors of the PCA_RAW scores;

- the columns 14-16 show the three vectors of the PCA_MNCN scores;

- the columns 17-19 show the three vectors of the PCA_AUTO scores.

[0120] The two-dimensional matrix thus reaches {(r x c), 19} dimensions and for each of the 19 obtained columns the corresponding distribution function is calculated that is 256 points in length.

[0121] The first part of the colourgram is obtained by joining in sequence the 19 frequency distribution curves, which lead to the construction of a vector that is (19 x 256) = 4864 points in length.

[0122] The second part of the colourgram is obtained by joining in sequence the values of the vectors of the loadings obtained from PCA (3 values for each vector of the loadings x 3 principal components = 9 points) and of the eigenvalues of the 3 principal components (3 points), for each of the 3 models PCA (PCA_RAW, PCA_MNCN and PCA_AUTO). This procedure leads to the construction of a vector that is [(9 + 3) x 3] = 36 points in length.

[0123] The complete colourgram is then generated by joining in sequence the aforementioned first part and second part, so as to obtain a vector that is (4864 + 36) = 4900 points in length, which describes the colour properties of the image.

[0124] Figure 7 shows an embodiment of a colourgram in which all the peaks have been numbered. The description of the colourgram of Figure 7 is shown in the following Table 3: [0125] Table 3

[0126] Example 2 - Results of calibration models usable to determine the degree of phenolic ripeness of the grapes through the apparatus and the method according to the invention

[0127] By using the apparatus and the method according to the invention, in combination with an image acquisition device of known type (smartphone), images of samples of grapes of the Ancellotta and Lambrusco Salamino varieties were acquired and processed so as to produce information of interest correlated with the colour of the samples. Various mathematical models were calculated, based on techniques of selection of variables and multivariate calibration, to correlate the values of the parameters linked to the colour that were measured in the laboratory with the acquired images of the samples.

[0128] For all the samples 15 (physical and chemical) parameters were analyzed, which are listed in Table 4 below:

[0129] Table 4

[0130] The 15 parameters were determined by using known methods and apparatuses, namely reference analytical methods used in the specialized laboratories, in particular UV- Vis spectroscopy and high-performance liquid chromatography (HPLC). The models were processed by using a part of the samples from which the images were acquired, which is named“calibration set” (Cal), and validated by using a“prediction set” (Pred), comprising the images of the remaining samples. By comparing the obtained predictive values with the actual values obtained in the laboratory, it was then possible to validate the models, by evaluating the efficacy and reliability thereof.

[0131] The performances of the calibration models were expressed by the determination coefficient (R²), calculated both on the calibration set (R² Cal) and on the external prediction set (R² Pred). R² is particularly useful for comparing directly the models calculated on different parameters, inasmuch as it does not depend on the scale of measurement of the considered parameter. Its value can vary between 0 and 1 in calibration and can assume negative prediction values (if the model has very poor performance).

[0132] The performances of the models have further been expressed in terms of root- mean-square error (RMSE), calculated both in calibration (RMSEC) and in prediction (RMSEP). RMSE is the mean deviation found between the values measured experimentally and the corresponding values foreseen from the model and is expressed by the same measurement units as the parameter of interest. It should be pointed out that the values of R² and RMSE are affected both by the contribution of the error of the calibration model and by the experimental error associated with the analytical determination of the experimental parameter of interest.

[0133] In the Table 4 the results are summarized of the various models obtained for the samples of the two tested varieties of grape (Ancellotta and Lambrusco Salamino; 2016 vintage). It can be observed that for the grapes of the Ancellotta variety, satisfactory models were obtained for the prediction of all the parameters, except the“Optical density at 620 nm” parameter. The reason why this parameter is not predicted satisfactorily is that the absorbance value of the samples at 620 nm, corresponding to the spectrophotometric determination carried out in laboratory for this parameter, has extremely low values, near the base line of the spectral signal.

[0134] The obtained results are satisfactory also for the grapes of the Salamino variety, except for the“Intensity” and“Total Flavonoids” parameters. It should be noted that the flavonoids are a large family of hydroxylated polyphenolic compounds: the main group consists of the anthocyans (crimson red-coloured pigments), whilst many other flavonoids are not particularly coloured, like flavonols (pale yellow-coloured pigments) and flavanols (colourless pigments, which become dark in case of oxidation). Accordingly, the RGB digital images are more suitable for foreseeing with precision the antocyan content, which increases during ripening, significantly influencing the purple red colour of the grapes.

[0135] In general, except for the three aforesaid parameters, the error associated with the prediction of physical and chemical parameters of interest through the use of the apparatus and of the method according to the invention is limited and however absolutely compatible with the needs of the operators in the vine-growing and wine-making field. As it will appear clear to a person skilled in the art, by using the apparatus and the method according to the invention it is possible to make calibration models that are also suitable for varieties of red grape that are different from the Ancellotta and Lambrusco Salamino varieties. Moreover, similarly to what is done with known apparatuses and methods, for example in NIR spectrometry, the data acquired during routine use of the method and of the apparatus according to the invention can also be used to update the calibration models, so as to make the latter less influenceable by the annual variability of the parameters of interest of the grape.

[0136] Example 3 - Application of the method and of the apparatus according to the invention for evaluating the degree of roasting in samples of roasted coffee

[0137] It is known that the colour is a fundamental property of the coffee, because it is an indicator of the roasting process. The various types of coffee are in fact identified by both the type of mixture and by the colour exhibited by the mixture after the roasting process. More in detail, different types of coffee can be differentiated from one another on the basis of the recipe, namely on the basis of the specific mixture of different varieties of coffee in variable ratios. Each recipe is subjected to a specific roasting protocol, in which the parameters relating to times and temperatures are well defined. Consequently, the various recipes have a different colour and the latter has to be checked for each production batch in order to check that the production batch complies with the production specifications.

[0138] In the coffee-roasting industry, the colour of the recipe is measured by using a dedicated colorimeter. The result of the measurement is called the“colour index” and, in brief, it is a measure of reflectance of the sample in a narrow interval of wavelengths comprised in the infrared. Each recipe has an expected colour index and is evaluated as complying with the company specifications in the case in which the colour index value measured on the sample after grinding is comprised in an interval equal to the value of the expected colour index ± 4 units.

[0139] However, the known colorimeters enable the colour index to be measured only in narrow areas of the sample, thus not allowing possible unhomogeneity on the surface of the sample to be measured, which may cause measuring errors. Moreover, the colorimeter is a bench analytical instrument, which is positioned in a dedicated laboratory inside the production plant. Therefore, for carrying out the check of the conformity of the coffee batches after roasting, the operator is forced to remove a suitable quantity of sample and take the sample to the laboratory to perform the analysis. [0140] Consequently, the possibility has been evaluated experimentally of using the apparatus and the method according to the invention to make available a reproducible and efficient system for measuring the colour of the roasted coffee, which system is based on processing RGB digital images acquired from samples of different types of ground roasted coffee.

[0141] The images were acquired from the samples (also analyzed with a colorimeter of known type) by using the apparatus according to the invention and thus processed by applying the method according to the invention. The images acquired through the apparatus 1 in combination with an image acquisition device of known type (smartphone) were corrected and then converted through algorithm into colourgrams. Mathematical calibration models were then calculated, in particular multivariate calibration models, to correlate the colour index value measured with the colorimeter with the images of the samples acquired through the apparatus according to the invention. The acquired images were subdivided into a calibration set (Cal), which was used to calculate the models, and into a validation set (Pred), which was used to validate the models themselves. Many calibration models were calculated to identify the colour properties of the acquired images that are most correlated with the colour index of the samples of coffee.

[0142] The performances of the models were expressed in terms of root-mean- square error (RMSE), as in the previous Example 2. The RMSE values were calculated both in (RMSEC) and in prediction (RMSEP). Moreover, the performances of the models were also expressed in terms of determination coefficient (R²), calculated both in calibration (R² Cal) and in prediction (R² Pred). In the following Table 5 the results are shown of the best calibration model:

[0143] Table 5

[0144] It can be noted that very satisfactory results were

inasmuch as the error of the calibration model is less than the company tolerances (expected colour index ± 4 units).

[0145] The aforesaid results make it possible to replace the colorimeter with a system based on the apparatus and method according to the invention to evaluate the colour index of the ground roasted coffee. In this manner, the operator can evaluate the colour of the different typologies of ground roasted coffee directly on the production line, without the need to take the samples to the laboratory. The acquired RGB digital images and the results obtained can be stored in a company server, so as to create an archive of data that can be consulted remotely even after time has elapsed and are usable for carrying out further investigations or controls. It should further be noted that, although the results set out above were obtained by using the apparatus 1 in combination with a smartphone, it is clearly possible to replace the smartphone with another device (a tablet or a simple digital camera).

[0146] From what has been disclosed and exemplified above, it can be stated that the method and device according to the invention enable the drawbacks of the prior art to be overcome effectively and multiple advantages to be obtained. Variations on and/or additions to what has been disclosed and/or what has been illustrated in the attached drawings are further possible.

[0147] For example, although in the embodiment of the apparatus 1 disclosed with reference to Figures 1-5 the sample holder element 12 and the lid element 10 are moved manually, it is possible to equip the apparatus 1 with driving means of known type. The driving means can comprise, for example, rack or endless screw linear actuators, suitably sized and positioned between the body 3 and the sample holder element 12 and/or the lid element 10. The actuators can be powered by the battery 17.

[0148] Although in the embodiment of the apparatus 1 disclosed with reference to Figures 1-5 the lid element 10 is moved slidingly, it is possible to make an embodiment of the apparatus 1 in which the lid element is hinged on the body 3, at an end wall 5, 6 or at one of the side walls 7, 8.

[0149] Moreover, although in the embodiment of the apparatus 1 disclosed with reference to Figures 1-5 the sample holder element 12 is opened and closed at the first end wall 5, it is possible to make an alternative embodiment of the apparatus 1 in which the sample holder element 12 can be opened ad closed at the side of the body 3, namely can be opened ad closed at one of the side walls 7, 8.

[0150] It is further possible to make an embodiment of the apparatus 1 in which the sample holder element 12 and the lid element 10 can be both opened ad closed by sliding in the same direction Fl or F2.

Claims

1. Apparatus (1) for determining at least one physical parameter and/or at least one chemical parameter of a sample of a chromatically unhomogeneous material or product, comprising a controlled lighting image acquisition chamber (2), said controlled lighting image acquisition chamber (2) comprising a sample insertion and removal portion (2a) and an image acquisition portion (2b).

2. Apparatus (1) according to claim 1, wherein said controlled lighting image acquisition chamber (2) comprises lighting means (19) arranged for providing an internal lighting that is not affected by the external ambient luminosity.

3. Apparatus (1) according to claim 1, or 2, wherein said controlled lighting image acquisition chamber (2) comprises an internally hollow body (3), said body (3) comprising a plurality of walls (4, 5, 6, 7, 8) that altogether define an operating chamber (11) provided with an opening (9).

4. Apparatus (1) according to claim 3, as appended to claim 2, wherein said lighting means (19) is comprised in said operating chamber (11).

5. Apparatus (1) according to claim 3, or 4, wherein said plurality of walls (4, 5, 6, 7, 8) comprises a base wall (4), a pair of end walls (5, 6) and a pair of side walls (7, 8).

6. Apparatus (1) according to claim 5, as appended to claim 4, wherein said lighting means (19) is installed in inner faces of said end walls (5, 6) and of said side walls (7, 8).

7. Apparatus (1) according to claim 5, or 6, wherein said plurality of walls (4, 5, 6, 7, 8) comprises a plurality of free edges (5a, 6a, 7a, 8a) that altogether define said opening (9) and wherein said opening (9) is opposite to said base wall (4).

8. Apparatus (1) according to any one of claims 3 to 7, wherein said sample insertion and removal portion (2a) comprises a sample holder element (12) arranged for receiving said sample and a housing (13), said housing (13) being obtained in said operating chamber (11) and being arranged for receiving slidably said sample holder element (12).

9. Apparatus (1) according to claim 8, wherein said image acquisition portion (2b) comprises a lid element (10) and a portion of said operating chamber (11) that is comprised between said housing (13) and said lid element (10), said lid element (10) being arranged for enabling said operating chamber (11) to be alternately opened or closed.

10. Apparatus (1) according to claim 9, wherein said lid element (10) is received slidably in a grooved seat (18) that is obtained in said body (3).

11. Apparatus (1) according to any one of claims 3 to 10, wherein said controlled lighting image acquisition chamber (2) comprises a colour reference panel (40), said colour reference panel (40) being positioned inside said operating chamber (11).

12. Apparatus (1) according to claim 11 as appended to claim 8, or to any one of claims 9 to 11 as appended to claim 8, wherein said colour reference panel (40) is positioned on an abutment element (20) delimiting said housing (13).

13. Apparatus (1) according to any one of claims 8 to 12, wherein said sample holder element (12) is made in the form of a drawer.

14. Apparatus (1) according to any one of claims 9 to 13, wherein said lid element (10) comprises a housing portion (lOb) arranged for receiving an image acquisition device.

15. Apparatus (1) according to claim 14 as appended to claim 3, or to any one of claims 4 to 13 as appended to claim 3, wherein, in said housing portion (lOb), a window (lOi) is obtained that is arranged for putting said housing portion (lOb) in communication with said operating chamber (11).

16. Apparatus (1) according to any one of claims 2 to 15, comprising a battery (17) arranged for electrically supplying said lighting means (19).

17. Use of the apparatus (1) according to any one of claims 1 to 16 for determining at least one physical parameter and/or at least one chemical parameter of a sample of a chromatically unhomogeneous material or product.

18. Use of the apparatus (1) according to claim 17, wherein said sample of a chromatically unhomogeneous material or product is a sample of grapes and wherein said at least one physical parameter and/or at least one chemical parameter are correlated to the degree of phenolic maturity of said grapes.

19. Method for determining at least one physical parameter and/or at least one chemical parameter of a sample of a chromatically unhomogeneous material or product, comprising the following steps:

- Positioning said sample inside an apparatus (1) comprising a controlled lighting image acquisition chamber (2), in said controlled lighting image acquisition chamber (2) an operating chamber (11) being comprised that can be separated from the external environment and the ambient luminosity and is arranged for receiving said sample;

- Acquiring an RGB digital image of said sample by using an image acquisition device;

- Processing said acquired RGB digital image;

said processing comprising correcting said acquired RGB digital image, converting said acquired and corrected RGB digital image into a corresponding one-dimensional signal that describes the colour contents of said image, applying a multivariate calibration model to said one-dimensional signal, said multivariate calibration model being specific for said at least one physical parameter and/or said at least one chemical parameter, said applying comprising comparing said one-dimensional signal with said multivariate calibration model, and obtaining estimated values of said at least one physical parameter and/or said at least one chemical parameter through said comparing.

20. Method according to claim 19, wherein said positioning comprises:

- Moving a sample holder element (12) of said controlled lighting image acquisition chamber (2) in a housing (13) of said operating chamber (11) according to a direction (Fl), so as to extract said sample holder element (12) from said operating chamber

(ID;

- Inserting said sample in said sample holder element (12);

- Moving again said sample holder element (12) according to a further direction (F2), said further direction (F2) being parallel and opposite to said direction (Fl), so as to transfer said sample holder element (12) and said sample inside said operating chamber (11).

21. Method according to claim 20, comprising closing an opening (9) of said controlled lighting image acquisition chamber (2) by using a lid element (10), so as to separate said operating chamber (11) from said external environment and said ambient luminosity.

22. Method according to claim 21, comprising positioning said image acquisition device in a housing portion (lOb) that is comprised in said lid element (10), said positioning being carried out before or after said closing said opening (9).

23. Method according to claim 22, comprising switching on lighting means (19) that is comprised in said operating chamber (11), so as to achieve inside said operating chamber (11) luminosity conditions that are suitable for said acquiring an RGB digital image of said sample.

24. Method according to any one of claims 19 to 23, wherein said correcting comprises using a colour reference panel (40) that is comprised in said operating chamber (11).

25. Method according to any one of claims 19 to 24, wherein said converting said acquired RGB digital image into a corresponding one-dimensional signal comprises using an algorithm.

26. Method according to any one of claims 19 to 25, wherein said processing said acquired RGB digital image is carried out inside said image acquisition device or in a computer or server connected to said image acquisition device.

27. Method according to claim 26, wherein said computer or server is connected to said image acquisition device through a connection selected from the group consisting of: wired connection, connection to mobile data network and connection to wireless data network.

28. Method according to any one of claims 19 to 27, further comprising generating said multivariate calibration model through a procedure comprising the following steps:

- Acquiring a plurality of RGB digital images from a corresponding plurality of samples of said chromatically unhomogeneous material or product;

- Analysing said plurality of samples by using known analytical methods and apparatuses, so as to determine a plurality of values of said at least one physical parameter and/or said at least one chemical parameter;

- Processing said plurality of acquired RGB digital images, said processing comprising correcting said acquired images and converting said corrected images in a corresponding plurality of one-dimensional signals, said one-dimensional signals describing the colour contents of said images;

- Correlating mathematically said plurality of one-dimensional signals with said plurality of analytically determined values of said at least one physical parameter and/or said at least one chemical parameter, so as to obtain said multivariate calibration model.

29. Method according to any one of claims 19 to 28, further comprising archiving in a server o in a computer data obtained by acquiring said RGB digital image and/or data obtained by processing said acquired RGB digital image.

30. Method according to any one of claims 19 to 29, wherein said sample of a chromatically unhomogeneous material or product is a sample of grapes and wherein said at least one physical parameter and/or at least one chemical parameter are correlated to the degree of phenolic maturity of said grapes.

31. Method according to claim 30, wherein said at least one physical parameter is selected from the group consisting of: colour intensity, colour tone, optical density at 420 nm, optical density at 520 nm, optical density at 620 nm and red purity.

32. Method according to claim 30, wherein said at least one chemical parameter is selected from the group consisting of: anthocyanidins, total flavonoids and total anthocyans.

33. Program comprising a code for implementing the method according to claims 19 to 32 when said program is run in a computer.

34. Support that is readable by a computer and contains a program according to claim 33.

35. Computer in which a program has been loaded or stored according to claim 33.

36. Computer according to claim 35, said computer being provided with, or connected to, a digital camera.