SYSTEM FOR QUANTIFYING A COLOUR CHANGE

Abstract

A system (5) for quantifying a colour change in a colorimetric indicator (15), the system (5) comprises an image capture device (22) configured to acquire an image of an object (10) comprising the colorimetric indicator (15); and a processing device (20) configured to compare the acquired image to reference data (30) associated with the colourimetric indicator (15), and generate a quantitative output (28) associated with the acquired image.

Claims

1. A system for quantifying a colour change in a colorimetric indicator, the system comprising: an image capture device configured to acquire an image of an object comprising the colorimetric indicator; and a processing device configured to compare the acquired image to reference data associated with the colourimetric indicator, and generate a quantitative output associated with the acquired image.

2. A system according to claim 1, wherein the output is representative of a colour change in the colourimetric indicator.

3. A system according to claim 1, wherein processing device is capable of accessing a plurality of reference data sets, each data set being associated with a respective colourimetric indicator.

4. A system according to claim 1, wherein the system comprises a portable user device or a mobile monitoring apparatus, the portable user device or the mobile monitoring apparatus comprising the image capture device and/or processing device.

5. A system according to claim 4, wherein the image capture device comprises a camera of the portable user device or of the mobile monitoring apparatus.

6. A system according to claim 1, wherein the processing device is configured to perform image analysis of the acquired image.

7. A system according to claim 1, wherein the processing device is configured to compare the colour of the acquired image with colours of the reference data associated with the colourimetric indicator.

8. A system according to claim 7, wherein the colours of the reference data are stored, expressed and/or converted in a standard colour scale.

9. A system according to claim 7, wherein the colour of the acquired image is converted, expressed and/or stored in a standard colour scale.

10. A system according to claim 1, wherein the quantitative output is associated with the colour of the captured image and/or is representative of the colour change in the colourimetric indicator.

11. A system according to claim 1, wherein the object further comprises at least one reference colour region, the at least one reference colour region corresponding a colour of the indicator in a predetermined state, and wherein the system is configured to capture an image of the at least one reference colour region.

12. A system according to claim 1, wherein the system is configured to illuminate the object during image capture at a predetermined light intensity.

13. A system according to claim 1, wherein the system is configured to normalise the captured image, wherein normalisation is performed by capturing an image of a normalisation region on the object.

14. (canceled)

15. A system for quantifying a colour change in a colorimetric indicator, the system comprising: an object comprising a colorimetric indicator; an image capture device configured to acquire an image of the object and/or of the colorimetric indicator; and a processing device configured to compare the acquired image to reference data associated with the colourimetric indicator, and generate a quantitative output associated with the acquired image.

16. A method for quantifying a colour change in a colorimetric indicator, wherein the method comprises: acquiring an image of an object comprising a colorimetric indicator; comparing the acquired image to reference data associated with the colourimetric indicator; and generating a quantitative output associated with the acquired image.

17. The method of claim 16, comprising acquiring the image using an image capture device, processing the image using a processing device, and comparing the acquired image to reference data using the processing device.

18.-19. (canceled)

20. The method of claim 16, comprising the preliminary step of selecting the type of object or indicator to be captured by the image capture device.

21. The method of claim 16, comprising using a template on the image capture device in order to locate the image capture device relative to the object prior to acquiring the image.

22. The method of claim 16, comprising normalising the acquired image.

23. A computer program comprising instructions which, when the program is executed by a processing device, causes the processing device to: acquire an image of an object comprising a colorimetric indicator; compare the acquired image to reference data associated with the colourimetric indicator; and generate a quantitative output associated with the acquired image.

24. (canceled)

25. A computer-readable storage medium comprising the computer program of claim 23.

26. (canceled)

Description

BRIEF DESCRIPTION OF DRAWINGS

[0088] Embodiments of the present disclosure will now be given by way of example only, and with reference to the accompanying drawings, which are:

[0089] FIG. 1 a schematic view of a system according to an embodiment;

[0090] FIG. 2 a screenshot of an output using the system of FIG. 1 on a first indicator, before exposure of the indicator to UV radiation;

[0091] FIG. 3 a screenshot of an output on the indicator of FIG. 2, after exposure of the indicator to a dose of UV radiation;

[0092] FIG. 4 a screenshot of an output using the system of FIG. 1 on a second indicator, before exposure of the indicator to UV radiation;

[0093] FIG. 5 a screenshot of an output on the indicator of FIG. 4 after exposure of the indicator to a dose of UV radiation;

[0094] FIG. 6 a screenshot of an output using the system of FIG. 1 on a third indicator, after exposure of the indicator to a dose of UVC radiation;

[0095] FIG. 7 a graph showing colour difference ΔE* during generation of reference data for two different irradiation levels;

[0096] FIGS. 8 and 9 images of the exposed samples corresponding to the data points shown in FIG. 7;

[0097] FIG. 10 a method of quantifying a colour change according to an embodiment;

[0098] FIG. 11 a method of quantifying a colour change according to another embodiment

[0099] FIG. 12 an alternative embodiment of a card configured to be used in the system of FIG. 1;

[0100] FIG. 13 an illustration of an optional step of a method of quantifying a colour change according to another embodiment;

[0101] FIG. 14 an illustration of a template for use in the system of FIG. 1;

[0102] FIGS. 15 to 17 schematic views of a system according to another embodiment; and

[0103] FIGS. 18 and 19 alternative embodiments of the card of FIG. 12.

DETAILED DESCRIPTION

[0104] Referring to FIG. 1 there is shown a system for quantifying a colour change, generally designated 5, according to a first embodiment.

[0105] The system 5 includes an image-capturing device 22, which in this embodiment is a camera.

[0106] The system 5 also includes a processing device 20, which in this embodiment is supported by a smartphone.

[0107] The image-capturing device 22 is configured to acquire an image of an object 10, which in this embodiment is a patch or a card having on its surface a region having a colourimetric indicator 15. In FIG. 1, the step of acquiring the image is represented by arrow 110. There is also provided an illumination means 23, e.g. a flash 23, to illuminate the object at the time of image capture, which may improve the reliability of the image capture.

[0108] In use, the colourimetric indicator 15 is configured to change colour upon exposure to UV radiation 19. It will be understood that, in other embodiments, the indicator may be chosen to change colour upon exposure to another type of stimulus, such as in response to exposure to a different type of radiation or to a chemical compound or substance.

[0109] The processing device is configured to compare the captured image to reference data 30 associated with the colourimetric indicator 15. The reference data is in digital/electronic form.

[0110] As shown in FIG. 1, the reference data 30 can be stored on the processing device 20 or connected directly to hardware comprising or being provided with the reference data 30. In such instance, the step of acquiring the image is represented by arrow 121.

[0111] As shown also in FIG. 1, the reference data 30 can be stored remotely from the processing device 20 such as in internet cloud 40, and can be accessed by any suitable wired or wireless connection such as Bluetooth or Wi-Fi. In such instance, the step of acquiring the image is represented by arrow 122.

[0112] In use, subsequent to acquisition of the image, the system 5 compares the acquired image of the indicator 15 to the reference data 30. Advantageously, in order to improve consistency and reliability, the processing device 20 converts or expresses the colour of the captured image into a standard and/or uniform colour scale, which in his embodiment is the ‘L*a*b*’ or ‘CIELAB’ colour scale. The processing device 20 then compares the colour of the acquired image to the reference data 30, which is also expressed in the same standard and/or uniform colour scale, e.g. ‘L*a*b*’ or ‘CIELAB’ colour scale. Comparison of the acquired image with the reference data 30 is explained in more details below.

[0113] Subsequent to the comparison step, the system 5, e.g. processing device 20, generates a quantitative output 28 associated with the colour of the acquired image and/or associated with the colour change of the indicator 15. In this embodiment, the quantitative output 28 is a numerical value (‘3’) that represents the level of colour change of the indicator 15 from an initial state (e.g., ‘1’) to a final (full colour change, e.g., ‘5’) state. The quantitative output 28 is displayed on a screen 25 of the processing device 20. The quantitative output 28 can be stored locally, e.g. on the processing device 20, or can be uploaded or stored remotely, for example on cloud 40, as shown by arrow 123.

[0114] A method for quantifying a colour change is illustrated in FIG. 10. The method comprises step 410 which comprises acquiring an image of an object comprising a colorimetric indicator. In step 420, the acquired image is compared to reference data associated with the colourimetric indicator. In step 430, a quantitative output associated with the acquired image is generated as a result of the comparison of step 420, which for example represents the colour change between the colour of the indicator in its initial or “unchanged” state, and the colour of the indicator in the acquired image.

[0115] The method of FIG. 10 may also include the preliminary (optional) step 405 of selecting the type of indicator to be captured by the device 20,720,820. This may be particularly useful when the processing device 20,720,820 is capable of capturing an image of different types of supports 10,110,210,310,610 having different features, shapes and/or indicators 15,155,215,315,615. Thus, in the example illustrating this step as shown in FIG. 13, step 405 includes selecting between two different types of indicators 701,702. Each type of indicator 701,702 will be associated with a respective set of reference data 30 which the processing device 20,720,820 will use to generate a quantitative output for the selected indicator 701,702.

[0116] Another embodiment of a method for quantifying a colour change is illustrated in FIG. 11. The method of FIG. 11 is similar to the method of FIG. 10, like parts denoted by like numerals, incremented by ‘100’. However, in FIG. 11, the method, subsequent to acquiring image in step 510, comprises converting the colour of the acquired image and in particular of the colourimetric indicator thereof, into a standard and/or uniform colour scale such as L*a*b* scale, as represented by step 515. In step 520, the acquired image is compared to reference data associated with the colourimetric indicator, which reference data are also expressed in the same standard and/or uniform colour scale such as L*a*b* scale. In step 530, a quantitative output associated with the acquired image is generated, similarly to step 430 of FIG. 10. Finally, and optionally, in step 540, information, data or file(s) associated with one or more the acquired image, colour values (e.g., in L*a*b* scale) derived from the acquired image, and/or quantitative output associated with the colour of the acquired image, is/are stored either locally (.e.g. on a hard drive) or remotely (e.g. on a remote server, cloud, network attached storage (NAS), data store or the like).

[0117] Methodology for Generation of Reference Data

[0118] Measurement Methods and Procedures

[0119] In the following examples, a UV colourimetric indicator was used.

[0120] The samples were exposed by UV-radiation at 254 nm wavelength using a UVP Trans-illuminator equipped with fluorescent UVC-tubes using two different irradiation levels (90 and 760 μW/cm.sup.2 respectively). The irradiation level at the sample plane was determined by a calibrated silicon detector with a precision aperture in front of the detector's photosensitive surface. An aperture was used to limit the exposure to a well-defined spot of about ø20 mm on the samples.

[0121] At certain times corresponding to exposures of 10000, 25000, 50000, 75000 and 100000 μJ/cm.sup.2, the exposure was briefly paused and the colour of the exposed area was measured using a PR-735 spectrophotometer. Also, a picture of the sample was taken. The measurements and pictures were taken with the sample placed in a light both using D65 illumination with high colour rendering index (>95).

[0122] Based on the colour coordinates in CIE 1976 L* a* b* colour space, the total colour difference ΔE* relative to a non-exposed sample was determined as:

ΔE*=√{square root over ((ΔL*).sup.2+(Δa*).sup.2+(Δb*).sup.2)}

[0123] where ΔL*, Δa* and Δb* are the differences between the individual coordinates. Typically the human eye is capable of detecting a colour change when ΔE* is 1-2 or higher.

[0124] Measurement Conditions

[0125] Ambient temperature 23±2° C. Sample temperature (during exposure) 30±5° C. Exposure wavelength 254±2 nm

[0126] Equipment:

TABLE-US-00001 Reference silicon detector 10 × 10 mm, inv. no. 500963 UVP Transilluminator 254 nm, no. 95-0153-02 Current amplifier Keithley 427, inv. no. 603159 Precision aperture Ø 8 mm, inv. no. 502607 Spectrophotometer PR-735, inv. no. 901491 Light booth True Color TC-60 Nikon D7000 digital camera

[0127] Results

[0128] The values resulting from the above measurements are shown in Table 1 and Table 2 below.

TABLE-US-00002 TABLE 1 Exposure with low irradiance (90 μW/cm.sup.2). Colour Exposure CIE 1976 L*a*b* colour coordinates difference μJ/cm.sup.2 L* a* b* ΔE* 0 82.2 −4.0 52.4 0.0 10000 77.8 6.3 40.9 16.0 25000 73.2 14.2 30.0 30.2 50000 69.4 21.3 18.4 44.3 75000 67.8 25.4 10.7 53.0 100000 66.4 27.8 5.4 58.9

TABLE-US-00003 TABLE 2 Exposure with high irradiance (760 μW/cm.sup.2) Colour Exposure CIE 1976 L*a*b* colour coordinates difference μJ/cm.sup.2 L* a* b* ΔE* 0 83.0 −4.8 52.5 0.0 10000 77.9 7.1 39.8 18.1 25000 73.5 16.0 28.0 33.5 50000 69.6 23.5 16.0 48.1 75000 66.3 28.0 8.0 57.7 100000 65.1 31.0 2.0 64.4

[0129] The results for ΔE* for the two irradiation levels are shown in FIG. 7. The results show that the change in colour after exposure to a certain dose of UV irradiation was very similar for the irradiation intensities of 90 and 760 μW/cm.sup.2.

[0130] Corresponding images of the exposed samples are shown in FIGS. 8 and 9, clearly showing an increase in colour change of the indicator upon increased exposure to UV radiation.

[0131] The uncertainty is estimated to ±8% of the reported exposure levels. The relative uncertainty for L*, a* and b* is ±2.

[0132] It will be noted that no absolute uncertainty is given for L*, a* and b* as the measurement geometry is not well defined (detection about 15° normal to the sample surface, illumination close to diffuse).

Examples

[0133] Referring now to FIGS. 2 and 3, there is shown a screenshot 150a of a smartphone screen using an app according to an embodiment. In this embodiment, the colourimetric indicator is provided on a support in the form a wristband 110. An image 126a of the wristband 110 is acquired and is displayed in the screenshot 150a. Following conversion of the colour of the indicator on the wristband 110 into L*a*b* scale, the resulting colour value was compared to a reference data corresponding to this particular indicator, and a quantitative output 128a was generated. In this case, as no colour change occurred in the indicator, the output was “1”, signifying that no colour change had occurred.

[0134] In FIG. 3, after exposure of the indicator 115 on the wristband 110 to a dose of UV radiation, another image 126b was acquired and displayed on screenshot 150b. Following conversion of the colour of the indicator 115 on the wristband 110 into L*a*b* scale, the resulting colour value was compared to the same reference data used in FIG. 2, and a quantitative output 128b was generated. In this case, as exposure to UV radiation caused a visible colour change, the output was “5”, signifying that a significant colour change had occurred.

[0135] FIGS. 4 and 5 are similar to FIGS. 2 and 3, but using a different colourimetric indicator, show as 215a,215b, which in this embodiment is supported on a circular patch 210. In FIG. 4, the image 226a was acquired before exposure to UV radiation, and no colour change had occurred, thus leading to the generation of a quantitative output 228a (“1”) corresponding to a lack of colour change. However, in FIG. 5, following exposure to a certain level of UV radiation, a small colour change in the indicator 215b was observed, leading to the generation of a quantitative output 228b (“2”) corresponding to a relatively small colour change.

[0136] Referring now to FIG. 6, yet another indicator 315 was used. In this embodiment, the support 310 carrying the indicator 315 further has reference regions 316 and 317 which provide a user with additional visual aid to assess a potential change in colour. In this embodiment, region 316, shown in orange, is a reference region provided in a colour which matches the colour that the indicator is expected to reach after exposure to a predetermined level of UV irradiation, here corresponding to a level sufficient to kill all “MRSA” bacteria. The support also has another region 317, shown in pink, which is a reference region provided in a colour which matches the colour that the indicator is expected to reach after exposure to a predetermined (but different to region 316) level of UV irradiation, here corresponding to a level sufficient to kill all “C-Diff” bacteria. In this embodiment, following exposure to a low level of UV radiation, the indicator 315 displayed (in image 326) a small colour change compared to its initial state, leading to the generation of a quantitative output 328 (“2”) corresponding to a relatively small colour change. Although the quantitative output expresses a reliable means of assessing the colour change to a user, the additional reference regions 316 and 317 provide an additional and convenient means of cross-checking the analytical and quantitative output 328, thus further improving reliability. For example, although the user would know that the value “2” in the output 328 corresponds to a corresponding level of UV exposure which in this case would not be sufficient to kill MRSA of C-Diff, the additional reference regions 316 and 317 provide an additional and convenient means of cross-checking this result.

[0137] Referring now to FIG. 12, there is shown another embodiment of a support 610 for use in the system 5 of FIG. 1. In this embodiment, the support 610 carrying the indicator 615 is a card 610 which is similar to the support 310 of FIG. 6, like parts denoted by like numerals, incremented by ‘300’. However, in this embodiment, the card 610 also has a normalisation region 670.

[0138] The purpose of the normalisation region 670 is to adjust measurement of the colour of indicator region 615 based on ambient light conditions, such as brightness. The normalisation region 670 contains three separate portions, each corresponding to a specific colour. In this embodiment, the normalisation region 670 is a grey-scale region and consists of a white portion 671, a 50% grey portion 672 and a black portion 673. Without wishing to be bound by theory, it is believed that the apparent brightness to an observer of a matt grey surface is independent from the observer's viewing angle. Thus, the provision of a grey-scale reference region provides a standard portion for normalisation during image capture. In addition to providing a means for measuring exposure, a grey scale reference region 670 provides a convenient reference for white balance, or colour balance, allowing the camera to compensate system 5 for varying illumination sources at the time of image capture.

[0139] The grey scale reference region 670 may be used for in-camera white balance processing or post-processing. In use, for instant normalisation, when an image of card 610 is captured (and in particular of the indicator 615), an image of the grey scale reference region 670 is also captured and used to adjust white balance for a number of images, and in particular for the images captured as the same time as the grey scale reference region 670. In the case of post-processing normalisation, an image of the grey scale reference region 670 is taken when the image of the card 610 is taken (and in particular of the indicator 615), and an image processing software uses the data from the pixels in the grey scale reference region 670 of the captured image to adjust light balance for the whole image captured.

[0140] Alternative embodiments of the card 610 of FIG. 12 are shown in FIGS. 18 and 19, like parts denoted by like numerals, but supplemented by “b” ad “c” respectively.

[0141] In the embodiment of FIG. 18, card 610b includes a normalisation region 670b which has a single grey-scale portion 672b. In this embodiment, the grey portion 672b has a colour value (in CMYK) of C51, M43, Y30 and K59, which was found to provide optimum results in terms of quality and reliability.

[0142] In the embodiment of FIG. 19, card 610c includes a printed normalisation region 670c which has a single grey-scale portion 672c, as in FIG. 18. In this embodiment, the indicator 615c is in the form of a disc 615c which can be placed on the card 610c before an image is captured.

[0143] FIG. 14 shows an illustration of a template 880 for use in the system of FIG. 1. If different types of indicator are available, then a user choses the type of indicator being used, as explained in relation to FIG. 13. The processing device 820 then displays an electronic template 880 on its screen. The purpose of the template 880 is to help a user superimpose the template with the object 610 before an image of the object 610 is captured. Advantageously, this may improve the reliability of the image capture by ensuring the conditions under which an image is captured, e.g. angle, distance, etc, are similar.

[0144] In this embodiment, the template 880 of FIG. 14 is a template for use with the card 610 of FIG. 12. Thus, using the template 880, a user is assisted in placing the camera of the processing device 820 over the card 610. This may help ensure accurate and reliable image capture of the various parts of the card 610, including in particular indicator portion 615 (superimposed with indicator portion template 815), and optionally, if present, reference portions 616,617 (superimposed with reference portions template 816,817) and/or normalisation region 670 (superimposed with normalisation region template 870).

[0145] Referring to FIGS. 15 to 17 there is shown a system 905 for quantifying a colour change according to another embodiment. The system 905 is generally similar to the system 5 of FIG. 1, like parts being denoted by like numerals, but incremented by ‘900’.

[0146] The system 905 includes a mobile monitoring device in the form of a robot 921. The robot is mounted on wheels 981 and is battery-powered such that it is able to move within a predetermined area which in this embodiment is a hospital room. The room is exposed to continuous or intermittent exposure to UVC radiation for sterilization purposes. A UVC dosimeter card 910 (similar to the card 310 of FIG. 6 or the card 610 of FIG. 12) is located on a tray 985. As the room is exposed to continuous or intermittent exposure to UVC radiation for sterilization purposes, the UVC dosimeter card 910, and in particular indicator portion 915, reacts and changes colour in response to the exposure dose of UVC radiation.

[0147] The UVC dosimeter card 910 is shown in more detail in FIG. 16.

[0148] The UVC dosimeter card 910 also has a reference mark 919 which in this embodiment is in the form of a QR code. The QR code 919 may contain information relating to the nature of the object, the location of the object, etc.

[0149] In use, the robot 921 moves around the room searching for objects to be processed. The robot includes a camera 982 which is able to scan for objects to be processed. As shown in FIG. 15, when UVC indicator card 910 is within the field of view of camera 982, robot 921 stops and scans QR code 919 for information.

[0150] The robot 921 can then process the UVC indicator card 910 in similar fashion as described above in relation to the system of FIG. 1. In particular, as shown in FIG. 17, the robot 921 acquires an image of the card 910 (and in particular of indicator portion 915) using integrated camera 922, under illumination by integrated flash 923. The robot 921 then generates a quantitative output associated with the acquired image, using an integrated processing device.

[0151] In some embodiments, the robot 921 is configured to send a signal or command, based on the quantitative output associated with the card 910. In particular, if the quantitative output generated by the robot 921 is below a predetermined level, the robot 921 may send a command or signal that may trigger an increase in the level or dose of UVC in or near the location of the indicator card 910. If the quantitative output generated by the robot 921 is above below a predetermined level, the robot 921 may send a command or signal that may trigger a decrease in the level or dose of UVC in or near the location of the card 910. If the quantitative output generated by the mobile monitoring apparatus, e.g. robot, is at or near a predetermined level, the mobile monitoring apparatus, e.g. robot, may either not send any a command or signal or may send a command or signal that may trigger maintenance of the level or dose of UVC in or near the location of the card 910.

[0152] In some embodiments, the robot 921 may be configured to send or transmit the quantitative output to a receiving unit (not shown), e.g. by Wi-Fi, Bluetooth, or the like, which can then be reviewed by an end user.

[0153] It will be appreciated that the embodiments of the invention hereinbefore described are given by way of example only and are not meant to limit the scope thereof in any way.

[0154] Method steps of the invention can be performed by one or more programmable processors executing a computer program to perform functions of the invention by operating on input data and generating output. Method steps can also be performed by special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit) or other customised circuitry. Processors suitable for the execution of a computer program include CPUs, Graphics Processing Units (GPUs), maths co-processors, and microprocessors, and any one or more processors. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. The essential elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks. The processor may receive the data via a data bus or by other communications forms, such as wirelessly. Information carriers suitable for embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, e.g. EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in special purpose logic circuitry.

[0155] To provide for interaction with a user, the invention can be implemented on a device having a screen, e.g., a CRT (cathode ray tube), plasma, LED (light emitting diode) or LCD (liquid crystal display) monitor, for displaying information to the user and an input device, e.g., a keyboard, touch screen, a mouse, a trackball, and the like by which the user can provide input to the computer. Other kinds of devices can be used, for example, feedback provided to the user can be any form of sensory feedback, e.g., visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic, speech, or tactile input.