Patent Description:
Near infrared (NIR) spectroscopy is known to be used for commercial grading of internal quality attributes of fruits such as taste and the presence of rots. However, detection of small and/or localised internal defects is often very difficult.

United Kingdom patent <CIT> to MAF Agrobotic (MAF) discloses a device and method for non-destructive defects in fruits and vegetables. The method uses two sources of electromagnetic radiation, one emitting in a low band and the other in a high band. The mean wavelength of the high band and the mean wavelength of the low band are separated, for example, by at least <NUM> nanometres (nm).

A control device is adapted so as to be able to switch on one then the other of the two sources of electromagnetic radiation in alternation. The two sources of radiation are never switched on simultaneously. The beams are substantially identical in direction and in shape and would coincide if they were switched on simultaneously.

MAF discloses calculation of a simple index of defectiveness. One example of an index is a ratio of the powers transmitted in the low band and high band. The index of defectiveness of an object is compared with at least one predetermined value, so as to be able to sort the object according to its index of defectiveness.

<NPL> (Upchurch) discloses using interactance measurements to detect internal breakdown in apples. An apple is placed on a light box so that light enters the calyx or lower end. A fibre optic probe is placed in contact with a cheek of the apple midway between the stem (upper) end and the calyx end. Only one site was selected for each apple.

Upchurch notes that transmittance is a non-destructive technique for identifying apples with internal breakdown. The technique is however said to be difficult to implement into an online inspection system.

In the case of apples, an internal defect known as vascular browning is very difficult to detect from a single ratio of two signals. Vascular browning is characterised by small open cavities near an apple core. The core itself is an open cavity. Vascular browning cavities discolour only mildly, turning light brown with oxidation. The combination of small size, proximity to the core, and a lack of strong absorbance changes makes detection challenging.

<NPL> (Clark) discloses techniques for the detection of an internal browning disorder in apples. Clark discloses placing fruit centrally on a fruit holder by hand. Four different orientations of light source, fruit orientation and transmission detector were investigated. Orientation of the fruit with respect to a lamp and detector geometry was found to have a pronounced effect on the amount of light transmitted by the fruit.

Clark notes that sample averaging from up to four different locations around an apple could lead to improved precision. However, at grading speeds this may be impractical. Multiple measurements are said to be acceptable for manual experiments with limited numbers of fruit where careful control of the light source, fruit orientation and detector geometry can be maintained for successive readings at different sites.

In the case of onions, traditional NIR technology suffers a high false positive rate. The misclassification of good onions as defective is estimated to be as high as <NUM>% in some cases. This problem represents a significant barrier to the effective use of NIR technology for defect sorting in the onion industry.

<CIT> and Japanese patent specification <CIT> both disclose techniques for determining characteristics of articles such as fruits and vegetables, based on profiles of the ratio of spectroscopic values at different wavelengths.

It is an object of at least preferred embodiments of the present invention to address some of the aforementioned disadvantages. An additional or alternative object is to at least provide the public with a useful choice.

In accordance with an aspect of the invention, there is provided a method for determining at least one internal quality attribute of an article of agricultural produce according to claim <NUM>.

The term 'comprising' as used in this specification means 'consisting at least in part of'. When interpreting each statement in this specification that includes the term 'comprising', features other than that or those prefaced by the term may also be present. Related terms such as 'comprise' and 'comprises' are to be interpreted in the same manner.

In an embodiment the article has an axis between a first pole and a second pole, a plurality of latitudes along the axis, and a plurality of longitudes around a circumference of the article; the first spectroscopic values are associated to respective longitudes representing respective longitudes of the article to which low band light is directed from the at least one low band light source; and the second spectroscopic values are associated to respective longitudes representing respective longitudes of the article to which high band light is directed from the at least one high band light source.

In an embodiment the at least one measured spatial profile includes a first measured spatial profile, the first measured spatial profile including at least a first ratio and a second ratio, the longitude associated to the first ratio not equal to the longitude associated to the second ratio.

In an embodiment the at least one measured spatial profile includes a plurality of at least <NUM> ratios each associated to different longitudes.

In an embodiment the article has an axis between a first pole and a second pole, a plurality of latitudes along the axis, and a plurality of longitudes around a circumference of the article; the first spectroscopic values are associated to respective latitudes representing respective latitudes along the axis of the article to which low band light is directed from the at least one low band light source; and the second spectroscopic values are associated to respective latitudes representing respective latitudes of the article to which high band light is directed from the at least one high band light source.

In an embodiment a latitude associated to the first ratio is equal to a latitude associated to the second ratio.

In an embodiment the at least one measured spatial profile includes a second measured spatial profile, the second measured spatial profile including at least a first ratio and a second ratio each associated to the same latitude not equal to the latitude associated to the first ratio and the second ratio of the first measured spatial profile.

In an embodiment the at least one measured spatial profile includes at least <NUM> measured spatial profiles, the measured profiles each associated to different latitudes.

In an embodiment the method further comprises determining the at least one internal quality attribute at least partly from a comparison of a signature value associated to the at least one measured spatial profile with a reference value associated to the at least one reference spatial profile.

In an embodiment the signature value is determined from a subset of the ratios of the at least one measured spatial profile.

In an embodiment the at least one low band light source and the at least one high band light source are configured to direct light at least partly through the article simultaneously. In an embodiment an extractor is configured to extract, from the light transmitted through the article, at least one of the light transmitted from the at least one low band light source and the light transmitted from the at least one high band light source.

In an embodiment the article is at least partly spherical.

In an embodiment the lengths of at least some of the wavelengths associated to the low band of wavelengths are in the range <NUM> to <NUM>.

In an embodiment the first wavelength is of length <NUM>.

In an embodiment the lengths of at least some of the wavelengths associated to the high band of wavelengths are in the range <NUM> to <NUM>.

In an embodiment the second wavelength is of length <NUM>.

In accordance with a further aspect of the invention, there is provided an assessment system is configured to determine at least one internal quality attribute of an article of agricultural produce according to claim <NUM>.

In accordance with a further aspect of the invention, there is provided a computer program according to claim <NUM>.

The invention in one aspect comprises several steps. The relation of one or more of such steps with respect to each of the others, the apparatus embodying features of construction, and combinations of elements and arrangement of parts that are adapted to affect such steps, are all exemplified in the following detailed disclosure.

To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting. Where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

As used herein, '(s)' following a noun means the plural and/or singular forms of the noun. As used herein, the term 'and/or' means 'and' or 'or' or both.

The terms 'component', 'module', 'system', 'interface', and/or the like as used in this specification in relation to a processor are generally intended to refer to a computer-related entity, either hardware, a combination of hardware and software, software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a controller and the controller can be a component. One or more components may reside within a process and/or thread of execution and a component may be localized on one computer and/or distributed between two or more computers.

The term 'computer-readable medium' should be taken to include a single medium or multiple media. Examples of multiple media include a centralised or distributed database and/or associated caches. These multiple media store the one or more sets of computer executable instructions. The term 'computer readable medium' should also be taken to include any medium that is capable of storing, encoding or carrying a set of instructions for execution by a processor and that cause the processor to perform any one or more of the methods described above. The computer-readable medium is also capable of storing, encoding or carrying data structures used by or associated with these sets of instructions. The term 'computer-readable medium' includes solid-state memories, optical media and magnetic media.

The term 'connected to' as used in this specification in relation to data or signal transfer includes all direct or indirect types of communication, including wired and wireless, via a cellular network, via a data bus, or any other computer structure. It is envisaged that they may be intervening elements between the connected integers. Variants such as 'in communication with', 'joined to', and 'attached to' are to be interpreted in a similar manner. Related terms such as 'connecting' and 'in connection with' are to be interpreted in the same manner.

Preferred forms of the method for determining at least one internal quality attribute of an article of agricultural produce will now be described by way of example only with reference to the accompanying figures in which:.

<FIG> shows an example of a system <NUM> configured to determine at least one internal quality attribute of an article of agricultural produce <NUM>. In an embodiment the article of agricultural produce comprises an onion. The system is configured to detect the presence of botrytis fungus and/or pseudomonas bacteria as an example of an internal quality attribute of the onion.

In an example outside the scope of the invention, the system <NUM> is configured to detect the presence of vascular browning in at least one apple. The presence of vascular browning is an example of an internal quality attribute of the apple.

In an embodiment the article of agricultural produce is selected from a group of fruits and vegetables, for example onions, apples, potatoes, avocados, oranges, peaches, apricots, berries.

The system includes at least one laser diode positioned so as to direct a beam of light through the article <NUM>. The system <NUM> shows two laser diodes indicated at <NUM> and <NUM> respectively. The lasers <NUM> and <NUM> are configured to provide intense light within a small illumination area on the article <NUM>.

In an embodiment laser <NUM> is modulated with a square wave of frequency <NUM> and laser <NUM> is modulated with a square wave of frequency <NUM>. A pulser <NUM> controls the operation of the lasers <NUM> and <NUM>. In an embodiment the pulser <NUM> is configured to cause the lasers <NUM> and <NUM> to direct light at least partly through the article <NUM> simultaneously.

A detector <NUM> is positioned so as to measure the light transmitted through the article <NUM> from at least one of the lasers <NUM> and <NUM>. In an embodiment the detector <NUM> comprises a photodiode for example a silicon photodiode. The detector <NUM> determines at least one spectroscopic value associated to respective lasers. In an embodiment the detector <NUM> collects the light from laser <NUM> and/or laser <NUM>.

In the invention the lasers <NUM> and <NUM> operate at different wavelengths to each other.

In an embodiment laser <NUM> for example is configured to operate at a first wavelength in the range <NUM> to <NUM>. In an embodiment laser <NUM> for example is configured to operate at a first wavelength in the range <NUM> to <NUM>. In an embodiment laser <NUM> for example is configured to operate at a first wavelength in the range <NUM> to <NUM>. In an embodiment laser <NUM> is configured to operate at a wavelength of length <NUM>. In an embodiment laser <NUM> is configured to operate at a wavelength of length <NUM>. In an embodiment laser <NUM> is configured to operate at a wavelength of length <NUM>.

In an embodiment laser <NUM> for example is configured to operate at a second wavelength in the range <NUM> to <NUM>. In an embodiment laser <NUM> for example is configured to operate at a second wavelength in the range <NUM> to <NUM>. In an embodiment laser <NUM> for example is configured to operate at a second wavelength in the range <NUM> to <NUM>. In an embodiment laser <NUM> is configured to operate at a wavelength the range <NUM> to <NUM>. In an embodiment laser <NUM> is configured to operate at a wavelength of length <NUM>. In an embodiment the laser <NUM> is configured to operate at a wavelength of length <NUM>.

In an embodiment the lasers <NUM> and <NUM> are mounted in respective laser diode mounts (not shown) driven by respective laser diode drivers and controllers (not shown).

In an embodiment two lenses (not shown) are used to focus the light from the respective lasers to a target area on the surface of the article <NUM>. In an embodiment the target area has a <NUM> radius. In an embodiment an adjustable pinhole is used to remove the elliptical shape of the beam and any stray light.

In an embodiment the detector <NUM> is connected to an amplifier <NUM> to convert the current from the photodiode <NUM> to a voltage. In an embodiment the amplifier <NUM> comprises a trans-impedance amplifier. The amplifier <NUM> is connected to a lock-in amplifier <NUM>. In an embodiment the amplifier <NUM> is a multi-channel digital lock-in amplifier.

The lock-in amplifier <NUM> is configured to extract, from the light transmitted through the article <NUM>, the light signals from laser <NUM> and/or the light signals from laser <NUM> at least partly from the frequencies <NUM> generated by the pulser <NUM>. In an embodiment the lock-in amplifier is configured to extract the signals concurrently using modulation frequency. The amplifier <NUM> outputs two different light signals associated to the light received from laser <NUM> and laser <NUM> respectively.

In an embodiment the lasers <NUM> and <NUM> are modulated with square waveform shown at <NUM> and <NUM> respectively. Square wave modulation allows for a simplified driver circuit, as it requires a digital switch rather than analogue current control. In an embodiment the modulation frequency is selected so as to achieve an optimal trans-impedance gain and simplify the electronics design. Example modulation frequencies for the lasers include <NUM>, <NUM>, <NUM>, <NUM> respectively.

In an embodiment the lock-in amplifier <NUM> demodulates each of the signals associated to the respective lasers according to their frequencies. In an embodiment a low pass filter (not shown) is applied to the output of the lock-in amplifier <NUM>.

In an embodiment the detector <NUM> generates a plurality of absorption coefficient data values or spectroscopic values, referred to as absorption values. As the light from each of the lasers <NUM> and <NUM>, <NUM> passes through the article <NUM>, the light is subject to absorption. The detector <NUM> measures the extent of absorption by the article <NUM> of the light from the respective lasers.

A computing device <NUM> receives the light signals output by the lock-in amplifier <NUM>. In an embodiment the computing device <NUM> receives a plurality of spectroscopic values obtained from directing low band light from laser <NUM> at least partly through the article <NUM> toward the detector <NUM>. In an embodiment the computing device <NUM> also receives a plurality of spectroscopic values obtained from directing high band light from laser <NUM> at least partly through the article <NUM> toward the detector <NUM>.

In an embodiment the computing device <NUM> is connected to the lock-in amplifier <NUM>. In an embodiment the spectroscopic values obtained from the amplifier <NUM> and stored for example on a computer readable medium before being input to the computing device <NUM>.

A data store <NUM>, for example, maintains the absorption values obtained from the detector <NUM> and amplifiers <NUM> and <NUM>. These absorption values are used to determine at least one measured spatial profile associated to the article. The measured spatial profiles and determination of these measured spatial profiles are further described below. In an embodiment the measured spatial profile(s) is/are maintained in data store <NUM>.

Data store <NUM>, for example, maintains a spatial profile database of reference spatial profiles representing absorption coefficient data values for desirable and undesirable values for articles, for example healthy onions and rotten onions.

A comparator <NUM> compares at least one measured spatial profile from data store <NUM> with reference spatial profiles from spatial profile database <NUM> in order to assess at least one internal quality attribute for an article for example an onion. In an embodiment this internal quality attribute includes whether the onion is healthy or rotten.

In an embodiment the comparator <NUM> determines an assessment of at least one article. In an embodiment the comparator <NUM> determines at least one internal quality of the article <NUM> at least partly from a comparison of at least one measured spatial profile from the data store <NUM> with at least one reference spatial profile from the spatial profile database <NUM>.

In an embodiment the comparator <NUM> determines or receives at least one measured spatial profile associated to the article <NUM>. In an embodiment the measured spatial profile(s) each include a plurality of ratios of respective spectroscopic values associated to the low band laser <NUM> to respective spectroscopic values associated to the high band laser <NUM>. In an embodiment the measured spatial profile(s) each include a plurality of ratios of respective spectroscopic values associated to the high band laser <NUM> to respective spectroscopic values associated to the low band laser <NUM>.

In an embodiment at least one of the reference spatial profiles are associated to a class of articles of agricultural produce. For example, at least some of the spatial profiles may be associated to respective degrees of defects in onions, apples and other items of agricultural produce.

An output module <NUM>, for example, presents an output from the comparator <NUM>. In an embodiment the output module <NUM> presents an assessment of the onion to a user. In an embodiment the output module <NUM> transmits an assessment of the onion to a processor, for example to remove a rotten onion from a conveyor belt.

In an embodiment, the ratio of first wavelength light to second wavelength light is selected from the following:.

<FIG> shows an example of the system <NUM> of <FIG> adapted for use in a quality assurance application. In this example an article of agricultural produce is removed from a batch of similar articles. The selected article is assessed for quality. An assessment of the batch of articles is based at least partly on articles randomly selected from the batch and subjected to quality assessment.

As shown in <FIG> an article of agricultural produce, in this case an onion <NUM>, is seated on a cup mount <NUM>. In an embodiment the onion is shown with a stem end seated within the mount <NUM>.

A plurality of lasers direct light toward the onion. <FIG> shows lasers <NUM> and <NUM> by way of example. A photodiode <NUM> obtains absorption values representing the extent of absorption of light from lasers <NUM> and <NUM> by the onion <NUM>.

In an embodiment the cup mount <NUM> is adapted to rotate the onion <NUM> about an axis <NUM> extending between a first pole <NUM> and a second pole <NUM> of the onion <NUM>. As the onion <NUM> rotates about the axis <NUM>, different points on the surface of the onion <NUM> are exposed to the lasers <NUM> and <NUM>. In an embodiment, a point on the surface of the onion <NUM> is represented by a latitude along the axis <NUM> and a longitude around a circumference of the onion <NUM>.

In an embodiment the article is at least partly spherical. Apples and onions for example have a generally spherical shape. Points on the surface of a spherical article are therefore associated to respective latitudes and longitudes. In an embodiment, articles that are not spherical are associated to respective latitudes and longitudes.

In this embodiment the photodiode <NUM> obtains a plurality of absorption values at different orientations of the onion <NUM> with respect to the lasers <NUM> and <NUM>. The spectroscopic values associated to laser <NUM> and/or the spectroscopic values associated to laser <NUM> represent respective longitudes around the circumference of the onion <NUM>. The values represent respective longitudes to which low band light or high band light is directed from laser <NUM> or laser <NUM>.

In an embodiment the lasers <NUM> and <NUM> are adapted to move relative to the onion so as to obtain spectroscopic values at different latitudes of the onion <NUM>. In an embodiment there are positioned lasers additional to lasers <NUM> and <NUM> so as to obtain spectroscopic values at different latitudes of the onion <NUM>. The values represent respective latitudes to which low band light or high band light is directed from laser <NUM> or laser <NUM>.

<FIG> shows an example of the system <NUM> of <FIG> adapted for use in a high speed grading application, in the scope of the present invention. In this example an article of agricultural produce is assessed while being conveyed in a grading system.

As shown in <FIG> an article of agricultural produce, in this case an article <NUM> such as an onion, is supported on a roller <NUM> forming part of a high speed grading application. In an embodiment the onion is rotated about an axis <NUM> extending through the stem end of the onion while travelling along a conveyor.

A plurality of lasers direct light toward the onion. <FIG> shows <NUM> lasers, which include lasers <NUM>, <NUM>, <NUM>, and <NUM> for example. It will be appreciated that the number of lasers can be varied. In an embodiment the lasers are grouped into pairs of lasers. The pairs of lasers are positioned so as to direct light toward different parts of the onion at different incident angles. The lasers within each pair of lasers are positioned so as to direct light toward similar parts of the onion at similar incident angles.

In an embodiment the pairs of lasers are configured to direct, toward the onion, light associated to a first wavelength and light associated to a second wavelength. The first wavelength is different to the second wavelength. Within the respective pairs of lasers a first laser is configured to direct light of a first wavelength toward the onion and a second laser is configured to direct light of a second wavelength.

A photodiode <NUM> is positioned so as to obtain absorption values representing the extent of absorption of light from lasers <NUM>, <NUM>, <NUM>, and <NUM> directed to different points of the onion <NUM> representing different longitudes and latitudes. In an embodiment the photodiode is positioned between the roller <NUM> and the onion <NUM> and shaped so as to measure light absorption from at least one of the lasers.

In an embodiment laser <NUM> and laser <NUM> are configured to direct low band light at least partly through the article <NUM>, while laser <NUM> and laser <NUM> are configured to direct high band light at least partly through the article <NUM>.

The spectroscopic values associated to lasers <NUM>, <NUM>, <NUM> and <NUM> represent respective longitudes around the circumference of the onion <NUM>. The values represent respective longitudes to which low band light or high band light is directed from the lasers.

In embodiment laser <NUM> and laser <NUM> are configured to direct low band light and high band light respectively toward the same latitude of the article <NUM>. Laser <NUM> and laser <NUM> are configured to direct low band light and high band light respectively toward the same latitude of the article <NUM>. The latitude associated to laser <NUM> and <NUM> is different to the latitude associated to laser <NUM> and laser <NUM>.

<FIG> shows an example of multiple laser and detector positions adapted for use in either a quality assurance application or a high speed grading application.

A representation of an article <NUM> is shown having an axis <NUM> extending between a first pole <NUM> and a second pole <NUM>. The spectroscopic values are obtained from three detectors indicated at <NUM>, <NUM>, and <NUM> respectively. It will be appreciated that various embodiments include fewer than three or more than three detectors.

In an embodiment the detectors are positioned at different latitudes along the axis <NUM>. In an embodiment a single detector is configured to move along the axis <NUM> so as to obtain spectroscopic values representing different latitudes along the axis <NUM>.

The representation of the article <NUM> includes points on the surface of the article having different longitudes around the circumference of the article. Examples of points having different longitudes are indicated at <NUM>, <NUM> and <NUM> respectively.

In an embodiment the longitude of the detectors <NUM>, <NUM>, and <NUM> is assumed to be zero degrees. Point <NUM> is located at a longitude of <NUM> degrees, point <NUM> is located at a longitude of <NUM> degrees, and point <NUM> is located at a longitude of <NUM> degrees with respect to the detectors. In an embodiment there are <NUM> points evenly located around the surface of the article from <NUM> degrees to <NUM> degrees with respect to the detectors <NUM>, <NUM>, <NUM>.

There are <NUM> points shown in <FIG> around the circumference of the article that share the same latitude. In an embodiment having a points with three different latitudes and <NUM> different longitudes there would be a total of <NUM> different points on the surface of the article to which light from the lasers is directed. It will be appreciated that the number of latitudes of the points can be less than three or more than three. It will also be appreciated that the number of longitudes of the points can be less than or more than <NUM>.

Also shown in <FIG> is a spherical region <NUM> representing rotten tissue within the article <NUM>. It will be apparent that the presence of the spherical region <NUM> would be detected by examining the spectroscopic values obtained from detector <NUM>. However, examination of the spectroscopic values obtained from detector <NUM> or detector <NUM> would not detect the presence of the spherical region <NUM>.

<FIG> shows an example of spectroscopic values obtained from a healthy onion using light transport simulation software. Transmittance ratios at various longitudes (source locations) around the surface of the article are shown for different wavelengths of low band and high band light. Examples of wavelengths include <NUM>:<NUM> at <NUM>, <NUM>:<NUM> at <NUM>, and <NUM>:<NUM> at <NUM>. Transmittance ratios are shown on the y axis of the graph. Various longitudes around the circumference of the article are shown on the x axis of the graph.

It has been found that a ratio of light transmittance at two different wavelengths can be used to identify rots. However, this ratio is dependent on source-detector separation.

This effect can be explained by the diffusion approximation of the radiative transfer equation used to calculate the light transport in diffusive medium. The fluence (light energy per unit area), Φ, is calculated as: <MAT> where <MAT> is the attenuation coefficient, r is the source-detector separation distance, µa and µs' are the absorption and reduced scattering coefficients, respectively.

For two wavelengths, λ<NUM> and λ<NUM>, the corresponding fluences are ϕ<NUM> and ϕ<NUM>. Using equation (<NUM>) the ratio can be expressed as: <MAT>.

This ratio is not only dependent on the optical properties at these two wavelengths but also on the separation distance, r.

As shown in <FIG>, the measured transmittance ratio values shown at <NUM> increase with increased source-detector distance to a maximum at <NUM> degrees. The measured transmittance ratio values shown at <NUM> decrease to a minimum at <NUM> degrees. Therefore a change in transmittance ratio depends on the source-detector distance as well as the level of rot.

Measuring the source-detector separation distance is a possible solution but is not practical for online applications. According to equation <NUM>, the transmittance ratio changes depending on the difference of µeff at the two wavelengths.

If the two attenuation coefficients are equal, µeff<NUM> = µeff<NUM>, the ratio becomes: <MAT>.

This is now a ratio of the reduced scattering coefficients, independent of the source-detector separation distance. The <NUM> and <NUM> wavelength ratio shown at <NUM> has been found to have good classification performance. Furthermore, the attenuation coefficients are similar at these wavelengths, resulting in a transmittance ratio that is almost constant with distance.

Compared to healthy tissue, rotten tissue has higher absorption and lower scattering coefficients from <NUM> to <NUM>, resulting in different µeff. Therefore, the target ideal of µeff<NUM> = µeff<NUM>, for separation distance independence, will likely not hold if there is rotten tissue intersecting the light path.

The presence of rotten tissue will more likely cause a peak or trough on the scanned spatial profile. It is anticipated that such pattern differences in the spatial profiles could be the basis of a detection method, possibly with higher sensitivity because the method would be using additional spatial information with the ratio.

<FIG> shows the effect on the transmittance ratio profile for rots of different sizes and at different positions around an article using light transport simulation software.

Shown at <NUM>, <NUM> and <NUM> respectively are three different positions <NUM>, <NUM>, and <NUM> for the location of rot within an article. In each case the position of the rot is located near a stem end at a top latitude along an axis through the article, and horizontally moved to three different positions.

In each case, the rot produced a distinctive trough in the profile of the top latitude. The respective troughs are indicated at <NUM>, <NUM> and <NUM> respectively. The trough positions <NUM>, <NUM> and <NUM> correspond to the respective positions of the rot.

Shown at <NUM> is a position <NUM> of rot located close to the basal plate of the onion. The resulting spatial profile displays a trough <NUM> at the centre.

Shown at <NUM> is a bigger rot at a position <NUM> at a top latitude, causing a wider trough <NUM> in the top profile and a shallower trough <NUM> in the middle profile.

The results shown in <FIG> indicate that the ratio profiles at three different latitudes is sufficient to indicate the position and size of rot in an article. It will be appreciated that more than three latitudes can be used.

<FIG> shows an example of an assessment of internal quality attributes of three different onions. Light of a first wavelength of <NUM> and light of a second wavelength of <NUM> is directed toward the onions at a range of laser incident angles. For each of onions <NUM>, <NUM> and <NUM>, three measured spatial profiles are determined. It will be appreciated that in an embodiment the number of different measured spatial profiles determined includes at least three different measured spatial profiles.

Shown at <NUM> is a range of absorption values for a healthy onion. The values are shown as three different measured spatial profiles <NUM>, <NUM> and <NUM> each comprising ratios of the absorption values from the first wavelength to the absorption values from the second wavelength.

The ratios in spatial profile <NUM> for example share a common lower latitude value. The ratios in spatial profile <NUM> share a common middle or intermediate latitude value. The ratios in spatial profile <NUM> share a common upper latitude value. In an embodiment the latitudes associated to each of spatial profiles <NUM>, <NUM> and <NUM> are different to each other.

Each of the spatial profiles is shown associated to a spatial range of different laser incident angles, or longitudes around the article. The range is shown in <FIG> as <NUM>° to <NUM>°. It will be appreciated that this range can be varied. In an embodiment the spatial profiles <NUM>, <NUM> and/or <NUM> include at least a first ratio and a second ratio, the longitude associated to the first ratio not equal to the longitude associated to the second ratio. In an embodiment the spatial profiles <NUM>, <NUM> and/or <NUM> include at least <NUM> ratios associated to a plurality of respective different longitudes.

Shown at <NUM> is a range of absorption ratio values for an onion infected with Botrytis. The ratios of absorption values for each of the lower latitude <NUM>, middle latitude <NUM> and upper latitude <NUM> show a wide 'v' shape profile with a nadir at approximately <NUM>°.

It is to be expected that the central portion of the onions in this group have more rotten tissue being traversed by the light. Therefore the absorption values are lower. The drop in the ratio is indicative of a location of the rot within the onions, in this case localised to the centres of the onions.

Shown at <NUM> is a range of absorption ratio values for an onion infected with Pseudomonas. The ratios of absorption values for each of the lower latitude <NUM>, middle latitude <NUM> and upper latitude <NUM> show a wide 'v' shape profile with a nadir at approximately <NUM>°. The spatial profiles <NUM> when plotted show a similar pattern to the spatial profiles <NUM>.

The spatial profiles <NUM>, <NUM>, <NUM> of the healthy onion show a relatively flat ratio response across the spatial range of incident angles. The spatial profiles <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> on the other hand show a distinctive 'v' shape. Spatial profiles <NUM> show a response ratio with a relatively small standard deviation. Spatial profiles <NUM> and <NUM> show a response ratio with a larger standard deviation than spatial profiles <NUM>.

In an embodiment the comparator <NUM> from <FIG> compares the standard deviation of at least one ratio of respective first spectroscopic values to second spectroscopic values with the spatial profiles shown in <FIG>. The standard deviation of the ratios of absorption values are compared to the standard deviations of the stored spatial profiles. Based at least partly on this comparison of standard deviations, the onion under evaluation is assessed as being either healthy or rotten.

<FIG> shows examples of measured spatial profiles. A healthy onion <NUM> shows a largely flat line with some minor fluctuations, possibly caused by the variegated light absorbing character of the onion skin.

Rotten onions <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> showed a trough on the spatial profile. Both pseudomonas and botrytis caused the rot to develop first in the top middle core of the onion, so the troughs appeared in the centre of the profiles.

It was found that the larger the rot, the deeper the trough. The clear presence of the trough for onion <NUM> indicates that the system is sensitive to a very small rot.

The onion <NUM> had rotten tissue occupying almost the entire volume at the neck end. The profile level in that case was dramatically reduced compared to the other profiles but there was still a clear trough in the middle of the profile.

Hence the profile level in addition to profile pattern has the potential to be useful in the discrimination of severity of rot.

<FIG> shows an example of a technique used by the comparator <NUM> from <FIG> to compare measured spatial profiles from the data store <NUM> with reference spatial profiles from the spatial profile database <NUM>.

In an embodiment a single signature or discriminator value is used as a metric for comparison. In an embodiment a signature value associated to a measured spatial profile is compared with a reference value associated to a reference spatial profile. An internal quality attribute is determined at least partly from a comparison of a signature value and a reference value.

An example of a signature value is set out below: <MAT>.

In an embodiment the signature value is determined from a subset of the ratios of a measured spatial profile. For example, the variable meanSidePoints is the average of the first four points shown at <NUM> and the last four points shown at <NUM>. The variable meanCentrePoints is the average of the five points in the centre shown at <NUM>. The variable meanProfile is the average of all the points. In an embodiment.

A deeper trough on a profile will be associated with a higher discriminator value, therefore a threshold can be set to segregate the onions. Indicated at <NUM> are the ROC curves for the above comparison technique. The technique is found to provide higher AUC values and better performance than previous techniques.

<FIG> shows examples of raw spectra <NUM> and normalised spectra <NUM> recorded on healthy and rotten onions. Within the range <NUM>-<NUM>, the spectra have good signal to noise ratio due to the lower absorbance from water and pigments.

Normalisation cannot fully eliminate path length variations and could mask some spectral characteristics, but the general spectral features should be preserved. The average SNV normalised spectra for each severity score are shown at <NUM>, with the score <NUM> spectra being appreciably different.

Rotten onions were found to have lower transmittance in the wavelength range <NUM> to <NUM> and higher transmittance in the <NUM> to <NUM> range. Wavelengths chosen from these two ranges have the potential to be useful for detecting the presence of rotten tissue.

The middle region, from <NUM> to <NUM>, might then be used as a reference with which to normalise light intensity variations and/or spectral drift as the spectra are all closer to each other in that region as shown at <NUM>, even overlapping in the normalised view as shown at <NUM>. A transmittance ratio at two wavelengths has the potential to be an effective classification methodology.

<FIG> shows results of another set of measurements using three different onions, for example a healthy onion <NUM>, an onion infected with botrytis <NUM>, and an onion infected with pseudomonas <NUM>.

A healthy onion known to have given a false positive result using a <NUM>/<NUM> ratio classification method was used. The onions were measured on the middle position, and then measurements were repeated after carefully peeling away <NUM> to <NUM> dry skin layers.

The ratio profile was consistent with either the skin on or off for each of the onions and the healthy onion was detected correctly in both cases. Therefore the multi-laser system appeared to be successful in removing the skin interference problem.

A further experiment with apples, outside the scope of the present invention, showed that intensity ratios at <NUM>/<NUM> and <NUM>/<NUM> were useful for detecting vascular browning defects in apples. An experimental trial comprised <NUM> healthy and <NUM> defective Braeburn apples.

For clarity of results, a small number of results were selected for illustrative discussion. In this example the results were from <NUM> healthy and <NUM> defective apples.

<FIG> shows that the apple core of a healthy apple, which contains open seed cavities, produced a distinctive trough in the spatial profile for the intensity ratios. The trough was centred at <NUM>° and was much deeper and smoother with the <NUM>/<NUM> ratio.

<FIG> shows an example using defective apples. The vascular browning defects in the apples were generally scattered around the core. This effectively broadened the trough in the spatial profiles.

<FIG> shows that asymmetry in the spatial profile was observed when the defect was small and localised to one side of the core.

<FIG> shows an embodiment of a suitable computing environment to implement embodiments of one or more of the systems and methods disclosed above. The computing environment for example may implement one or more of the components of <FIG>. These components include the data store <NUM>, the spatial profile database <NUM>, the comparator <NUM>, and the output module <NUM>.

The operating environment of <FIG> is an example of a suitable operating environment. It is not intended to suggest any limitation as to the scope of use or functionality of the operating environment. Example computing devices include, but are not limited to, personal computers, server computers, hand-held or laptop devices, mobile devices, multiprocessor systems, consumer electronics, mini computers, mainframe computers, and distributed computing environments that include any of the above systems or devices. Examples of mobile devices include mobile phones, tablets, and Personal Digital Assistants (PDAs).

Although not required, embodiments are described in the general context of 'computer readable instructions' being executed by one or more computing devices. In an embodiment, computer readable instructions are distributed via tangible computer readable media.

In an embodiment, computer readable instructions are implemented as program modules. Examples of program modules include functions, objects, Application Programming Interfaces (APIs), and data structures that perform particular tasks or implement particular abstract data types. Typically, the functionality of the computer readable instructions is combined or distributed as desired in various environments.

Shown in <FIG> is a system <NUM> comprising a computing device <NUM> configured to implement one or more embodiments described above. In an embodiment, computing device <NUM> includes at least one processing unit <NUM> and memory <NUM>. Depending on the exact configuration and type of computing device, memory <NUM> is volatile (such as RAM, for example), non-volatile (such as ROM, flash memory, etc., for example) or some combination of the two.

A server <NUM> is shown by a dashed line notionally grouping processing unit <NUM> and memory <NUM> together.

In an embodiment, computing device <NUM> includes additional features and/or functionality. One example is removable and/or non-removable additional storage including, but not limited to, magnetic storage and optical storage. Such additional storage is illustrated in <FIG> as storage <NUM>. In an embodiment, computer readable instructions to implement one or more embodiments provided herein are maintained in storage <NUM>. In an embodiment, storage <NUM> stores other computer readable instructions to implement an operating system and/or an application program. Computer readable instructions are loaded into memory <NUM> for execution by processing unit <NUM>, for example.

Memory <NUM> and storage <NUM> are examples of computer storage media. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, Digital Versatile Disks (DVDs) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by computing device <NUM>. Any such computer storage media may be part of device <NUM>.

In an embodiment, computing device <NUM> includes at least one communication connection <NUM> that allows device <NUM> to communicate with other devices. The at least one communication connection <NUM> includes one or more of a modem, a Network Interface Card (NIC), an integrated network interface, a radio frequency transmitter/receiver, an infrared port, a USB connection, or other interfaces for connecting computing device <NUM> to other computing devices. In an embodiment, communication connection(s) <NUM> facilitate a wired connection, a wireless connection, or a combination of wired and wireless connections. Communication connection(s) <NUM> transmit and/or receive communication media.

Communication media typically embodies computer readable instructions or other data in a "modulated data signal" such as a carrier wave or other transport mechanism and includes any information delivery media. The term "modulated data signal" includes a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal.

In an embodiment, device <NUM> includes at least one input device <NUM> such as keyboard, mouse, pen, voice input device, touch input device, infrared cameras, video input devices, and/or any other input device.

Device <NUM> also includes at least one output device <NUM> such as one or more displays, speakers, printers, and/or any other output device. In an embodiment the output module <NUM> from <FIG> is implemented at least partially on the output device <NUM>.

Input device(s) <NUM> and output device(s) <NUM> are connected to device <NUM> via a wired connection, wireless connection, or any combination thereof. In an embodiment, an input device or an output device from another computing device is/are used as input device(s) <NUM> or output device(s) <NUM> for computing device <NUM>.

In an embodiment, components of computing device <NUM> are connected by various interconnects, such as a bus. Such interconnects include one or more of a Peripheral Component Interconnect (PCI), such as PCI Express, a Universal Serial Bus (USB), firewire (IEEE <NUM>), and an optical bus structure. In an embodiment, components of computing device <NUM> are interconnected by a network. For example, memory <NUM> in an embodiment comprises multiple physical memory units located in different physical locations interconnected by a network.

It will be appreciated that storage devices used to store computer readable instructions may be distributed across a network. For example, in an embodiment, a computing device <NUM> accessible via a network <NUM> stores computer readable instructions to implement one or more embodiments provided herein. Computing device <NUM> accesses computing device <NUM> in an embodiment and downloads a part or all of the computer readable instructions for execution. Alternatively, computing device <NUM> downloads portions of the computer readable instructions, as needed. In an embodiment, some instructions are executed at computing device <NUM> and some at computing device <NUM>.

A client application <NUM> enables a user experience and user interface. In an embodiment, the client application <NUM> is provided as a thin client application configured to run within a web browser. The client application <NUM> is shown in <FIG> associated to computing device <NUM>. It will be appreciated that application <NUM> in an embodiment is associated to computing device <NUM> or another computing device.

Claim 1:
A method for determining at least one internal quality attribute of an article (<NUM>) of agricultural produce, comprising:
receiving a plurality of first spectroscopic values obtained from directing low band light in a first wavelength associated to a low band of wavelengths from at least one low band light source (<NUM>) for respective distances r through the article (<NUM>) toward at least one detector (<NUM>);
receiving a plurality of second spectroscopic values obtained from directing high band light in a second wavelength associated to a high band of wavelengths from at least one high band light source (<NUM>) for the same respective distances r through the article (<NUM>) toward the at least one detector (<NUM>),
wherein the first wavelength is lower than the second wavelength;
determining at least one measured spatial profile associated to the article comprising a plurality of transmittance ratios of respective first spectroscopic values to respective second spectroscopic values; and
determining the at least one internal quality attribute at least partly from a comparison of the at least one measured spatial profile with at least one reference spatial profile associated to a class of healthy articles of agricultural produce, characterized in that:
the first and second wavelengths have been selected so that the attenuation coefficient of the first and second wavelengths are the same or similar for a healthy article such that the transmittance ratio would be almost constant with distance for a healthy article.