METHOD OF CONTROLLING AUTO-EXPOSURE SETTINGS OF A MOBILE DEVICE HAVING A CAMERA

Abstract

A method is disclosed for controlling auto-exposure settings of a mobile device when capturing an image of a color reference card and of a test field. Provided are a color reference card and an optical test strip having the test field with a sample applied thereto. The color reference card has different color reference fields having known reference color values and one or more gray background fields having defined gray values. An exposure metering area is set and auto-exposure settings are determined based on a scene in the exposure metering area. The scene has at least part of the test field and at least part of the different color reference fields and the one or more gray background fields. The camera captures an image of the scene using the determined auto-exposure settings. A method of determining concentration of analyte in a sample by using a mobile device is also disclosed.

Claims

1. A method of controlling auto-exposure settings of a mobile device having a camera when capturing an image with the camera of at least part of a color reference card and of at least part of a test field of an optical test strip having a sample applied thereto, the method comprising: a) providing a color reference card and an optical test strip having a test field having a sample applied thereto, wherein the color reference card comprises a plurality of different color reference fields having known reference color values and one or more gray background fields having defined gray values; b) setting an exposure metering area and determining auto-exposure settings based on a scene in the set exposure metering area, wherein the scene in the set exposure metering area comprises at least part of the test field having the sample applied thereto, at least part of the plurality of different color reference fields and at least part of the one or more gray background fields; c) using the camera to capture an image comprising the scene of step b), wherein the determined auto-exposure settings of step b) are used.

2. The method according to claim 1, wherein the mobile device comprises a display and the method further comprises the step of providing visual guidance on the display for positioning the camera relative to an object, the object comprising at least part of the optical test strip and/or at least part of the color reference card.

3. The method according to claim 1, wherein the color reference card and/or the test strip comprises a position marker.

4. The method according to the claim 3, wherein determining the auto-exposure settings is initiated automatically when it is determined that the camera is in a defined position with respect to the color reference card based on the position marker.

5. The method according to claim 3, wherein the position of the camera with respect to the color reference card based on the position marker is determined and the exposure metering area is set as a function of the determined position.

6. The method according to claim 1, wherein the test field is in a defined position with respect to the color reference card during one or both of determining the auto-exposure settings for the camera and capturing the image.

7. The method according to claim 1, wherein determining the auto-exposure settings and/or capturing the image is initiated automatically once the presence of at least one object within a field of view and/or within a predetermined sector of the field of view of the camera is automatically detected, the object comprising at least part of the optical test strip and/or at least part of the color reference card.

8. The method according to claim 1, wherein the percentage of the scene in the set exposure metering area is selected from the group consisting of at least 5%, at least 10% and at least 15% of at least part of the one or more gray background fields.

9. The method according to claim 1, wherein the scene in the set exposure metering area comprises the entire color reference card.

10. The method according to claim 1, further comprising determining an item of admissibility information that indicates admissibility when each pixel or at least a predetermined group of pixels corresponding to the color reference fields in the image exhibit brightness values within limits selected from the group consisting of between 50 and 240 and between 80 and 220.

11. The method according to claim 1, further comprising determining the concentration of the analyte in the sample by using the image and at least part of the plurality of different color reference fields.

12. A mobile device having a camera and a display, the mobile device configured for performing at least steps b) and c) of claim 1.

13. A kit for determining the concentration of an analyte in a bodily fluid, the kit comprising: the mobile device according to claim 12; an optical test strip having a reagent test field; and a color reference card having a plurality of different color reference fields with known reference color values and one or more gray background fields having a defined gray value.

14. A non-transitory computer-readable storage medium having stored thereon computer-executable instructions for performing the method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0140] The above-mentioned aspects of exemplary embodiments will become more apparent and will be better understood by reference to the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0141] FIG. 1 shows a color reference card in plan view;

[0142] FIG. 2 shows an embodiment of a kit comprising the mobile device, a color reference card and an optical test strip;

[0143] FIG. 3 depicts determining auto-exposure settings based on the scene in the set exposure metering area and capturing the image;

[0144] FIG. 4 shows a flow chart of an embodiment of a method of controlling auto-exposure settings; and

[0145] FIG. 5 shows a flow chart of an embodiment of a method for determining the concentration of at least one analyte in a bodily fluid.

DESCRIPTION

[0146] The embodiments described below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of this disclosure.

[0147] In FIG. 1, a n exemplary embodiment of a color reference card 110 is shown in a plan view. The color reference card 110 comprises a plurality of color reference fields 112 having known reference color values. The color reference fields 112 may be arranged on the surface of the color reference card 110, such as on a substrate of the color reference card 110. In particular, the color reference fields 112 may be distributed equally over the surface of the color reference card 110, specifically, in such a way that the plurality of color reference fields 112 may be distributed over the entire surface of the color reference card 110. As an example, the color reference fields 112 may be arranged in matrix pattern, such as a rectangular matrix pattern. However, the color reference fields 112 may also be arranged in other ways, such as separately from each other. The color reference card 110 further comprises one or more gray background fields 114 surrounding the color reference fields 112 and/or framing the color reference card. The color reference fields 112 and the gray background fields 114 may not overlap each other.

[0148] The color reference card 110 may further comprise at least one window 116. Thus at least one optical test strip 118 or a part thereof may be visible through the window 116 when the color reference card 110 is placed on top of the optical test strip 118. Specifically, at least one reagent test field 120 comprised by the optical test strip 118 may be visible through the window 116 of the color reference card 110. As another example, the color reference card 110 may comprise the optical test strip 118 having at least one reagent test field 120, specifically in such a way that the at least one reagent test field 120 is accessible and visible.

[0149] Further, the color reference card 110 may comprise at least one position marker 122. The position marker 122 may particularly be an ArUco code. In FIG. 1, the position marker 122 specifically may comprise one or more ArUco codes, such as in the corners of a rectangular matrix comprising the color reference fields 112. Thus, generally, the position marker 122 may be arranged in at least one corner 124 of the color reference card 110. For example, at least one position marker 122 may be arranged in each of the corners 124 of the color reference card 110, specifically in such a way that the position marker 122 may be visible together with the plurality of color reference fields 112. Further, the position marker 122 may comprise information about the orientation of the color reference card 110.

[0150] In FIG. 2, an exemplary embodiment of a kit is shown in a perspective view. The kit comprises at least one mobile device 128 and at least one color reference card 110. Further, the kit comprises the at least one optical test strip 118.

[0151] The mobile device 128 may be or may comprise at least one of a cell phone, a smartphone, a tablet computer or the like. Further, the mobile device 128 has at least one camera 130. The camera 130 of the mobile device 128 may be configured for recording images, specifically color images. Thus, the camera 130 may be a color camera and may comprise at least three color sensors, such as at least one color sensor for the R, G, B colors.

[0152] Further, the mobile device 128 may comprise at least one processor 132. The processor 132 may be configured, specifically by software programming, to perform one or more of the method steps b), c) and d) of the method of controlling auto-exposure settings. Further, the processor 132 may be configured for supporting step ii) of the method for determining a concentration of an analyte. Exemplary embodiments of the above-mentioned methods are shown in FIGS. 4 and 5, respectively, and will be described in further detail below. Thus, reference may be made to the description of FIGS. 4 and 5.

[0153] The processor 132 may specifically be configured for supporting the setting of an exposure metering area and determining auto-exposure settings based on the scene 126 in the set exposure metering area. In the embodiment shown, the scene 126 in the set exposure metering area comprises the color reference card and the reagent test field. The processor 132 may further specifically be configured for capturing of at least one image comprising the scene 126. Specifically, the processor 132 may prompt a user of the mobile device 128 to capture the image. Additionally or alternatively, the processor 132 may be configured for automatically capturing the image of the color reference card 110, specifically when the color reference card 110 may be in a field of view.

[0154] The color reference card 110 has been described above (see FIG. 1). The color reference card 110 comprises the plurality of color reference fields 112 having known reference color values. Further, the color reference card 110 may comprise the at least one window 116. Thus, the optical test strip 118 may be visible through the window 116 of the color reference card 110, specifically when the color reference card 110 may be placed on top of the optical test strip 118 such that both, the color reference card 110 and the optical test strip 118, may be visible on the at least one image captured by the camera 130 of the mobile device 128. Specifically, the at least one reagent test region 120 of the optical test strip 118 may be visible through the window 116 of the color reference card 110.

[0155] The color reference card 110 may further comprise at least one position marker 122. The position marker 122 may be arranged on at least one surface of the color reference card 110 such that the marker 122 may be detectable by the camera 130 of the mobile device 128. The at least one marker 122 may be used for identifying the color reference card 110. Specifically, the processor 132 of the mobile device 128 may be configured for detecting the position marker 122 in a field of view of the camera 130.

[0156] FIG. 3 shows the situation when determining auto-exposure settings and capturing the image. Visual guidance is provided in this embodiment on the display in form of an outline 136 of the color reference card superimposed on the display 134 of the mobile device 128 in order to guide the user to position the camera such that the scene in the set exposure metering area which corresponds to the outline 136 comprises at least part of the reagent test field of the optical test strip having the sample applied thereto, and at least part of the plurality of different color reference fields and at least part of the one or more gray background fields. In the example shown, the scene in the set exposure metering area comprises the entire color reference card.

[0157] Determining the auto-exposure settings and capturing the image may be initiated automatically. The automatic determination of the auto-exposure settings may, e.g., be initiated automatically in case it is detected that, based on the position marker 122, the color reference card is within the set exposure metering area. Similarly, the image can then be automatically captured wherein the determined auto-exposure settings are used.

[0158] FIG. 4 shows a flow chart of an exemplary embodiment of a method of controlling auto-exposure settings of a mobile device 138.

[0159] The method comprises: [0160] a) (denoted with reference number 142) providing a color reference card and an optical test strip having a test field having a sample applied thereto, [0161] wherein the color reference card comprises a plurality of different color reference fields having known reference color values and one or more gray background fields having defined gray values, [0162] b) (denoted with reference number 144) setting an exposure metering area and determining auto-exposure settings based on the scene in the set exposure metering area; [0163] wherein the scene in the set exposure metering comprises at least part of the reagent test field of the optical test strip having the sample applied thereto, and at least part of the plurality of different color reference fields and at least part of the one or more gray background fields of the color reference card, and [0164] c) (denoted with reference number 146) capturing, by using the camera, an image comprising the scene of step b) [0165] wherein the determined auto-exposure settings of step b) are used.

[0166] The method may comprise additional steps that are not listed.

[0167] In step a) a color reference card 110 and an optical test strip 118 having a test field having a sample applied are provided. The processor 132 may be configured for guiding the user in providing the color reference card and the optical test strip by providing user guidance, e.g., in a visual format or in an audible format.

[0168] In step b) the exposure metering area is set and auto-exposure settings based on the scene 126 in the set exposure metering area are determined. For example, the processor 132 may be configured for prompting the user to place the color reference card in the field of view of the camera or the position of the color reference card 110 may be tracked by the mobile device via the position marker 122. As an example, the processor 132 may be configured for detecting the color reference card 110 in a field of view and further for determining the auto-exposure settings when the color reference card with the position marker 122 is detected in the set exposure metering area.

[0169] In step c) an image is captured. The capturing of the at least one image may be initiated by user action or may automatically be initiated, e.g., once the color reference card is detected in the field of view of the camera 130 based on the position markers 122. The image acquisition may be supported by processor 132 of the mobile device 128, and the storing of the images may take place in a data storage device of the mobile device. The at least one image comprises the scene of step b). For capturing the image, the determined auto-exposure settings of step b) are used.

[0170] In an experiment, two color reference cards similar to the one shown in FIG. 1 with gray background fields of different gray values were compared. Auto-exposure settings were determined based on each color reference card placed in the exposure metering area and images of each color reference card were then captured with the determined auto-exposure settings, respectively.

[0171] The following table shows how the brightness level of the gray background fields influenced the detected brightness of an exemplary color reference field on the color reference card by influencing the auto-exposure settings.

TABLE-US-00001 Gray level of gray background field Brightness of color reference field (r,g,b) Lighter gray (138/155/36) average of 20 images Darker gray (148/168/40) average of 13 images

[0172] The brightness of the exemplary color reference field was lower when a color reference card with brighter gray background fields was used compared to a color reference card with darker gray background fields. Even brighter or even darker gray background fields may be used to steer exposure levels more strongly to a desired exposure level. This can help to obtain images suitable for being used in the determining of the concentration of an analyte in a sample applied to the test field of a test strip when imaged together with the color reference card (e.g., by avoiding over- or underexposure of the test field or relevant fields of the color reference card needed for image correction in determining the analyte concentration).

[0173] FIG. 5 shows a flow chart of an exemplary embodiment of a method of determining the concentration of an analyte in a sample by using a mobile device 128 having at least one camera 130.

[0174] The method comprises: [0175] i) (denoted with reference number 138) controlling auto-exposure settings of the mobile device as described before when capturing, by using the camera (130), at least one image of at least part of a color reference card (110) and of at least part of a reagent test field (120) of an optical test strip (118) having a sample applied thereto, [0176] ii) (denoted with reference number 148) determining the concentration of the analyte in the sample by using the at least one image of at least part of the reagent test field (120) of the optical test strip (118) having the sample applied thereto, and at least part of the plurality of different color reference fields (112).

[0177] Regard step i) it is referred to the method of controlling auto-exposure settings 138 as described above. In step ii), e.g., the glucose concentration in a blood sample applied to the test field of the test strip may be determined from the color formation of the reagent test field using the at least one image captured. By using intensity values determined from one or more color reference fields card having known optical properties, the mobile device may be set up for calibrating and/or correcting the image, thus taking into account the internal processes of the camera and/or the mobile device when or before determining the at least one analyte concentration value.

[0178] While exemplary embodiments have been disclosed hereinabove, the present invention is not limited to the disclosed embodiments. Instead, this application is intended to cover any variations, uses, or adaptations of this disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

TABLE-US-00002 LIST OF REFERENCE NUMBERS 110 color reference card 112 color reference field 114 gray background field 116 window 118 optical test strip 120 reagent test field 122 position marker 124 corner 126 scene 128 mobile device 130 camera 132 processor 134 display 136 outline 138 controlling auto-exposure settings of a mobile device 140 providing a color reference card (110) and an optical test strip 142 setting an exposure metering area and determining auto-exposure settings 144 capturing an image 148 determining the concentration of an analyte