Colorimetric Test Strip with Multi-color Reference Points for Smartphone Image Correction, Image Correction Method, and Inspection System Thereof

Abstract

The present invention relates to a colorimetric test sheet equipped with multi-color reference points, an image correction method, and a system for overcoming non-linear image distortion of a smartphone camera. To precisely correct the inherent color distortion of smartphones (ISP, AWB, etc.) that is impossible with basic three-color markers, the present invention places a plurality of multi-color reference color patches around a QR code. In addition, to prevent handling contamination such as fingerprints, instead of excluding physical reference points in the outer area, a logic for generating 'Fake References' is introduced that mathematically extends and copies the coordinates of the real reference points inside outward, thereby perfectly performing spatial color interpolation (IDW, etc.) without divergence errors. Furthermore, as a specific embodiment, the present invention incorporates a detachable plasma separation membrane upper structure that suppresses red blood cell interference when whole blood is injected, thereby removing the upper contaminants entirely after a chemical reaction and taking a single shot of only the exposed lower support with a smartphone, thereby achieving precise quantitative readings at the level of medical devices without the need for expensive dedicated equipment.

Description

Technology Field

[0001] The present invention relates to a colorimetric inspection device, method, and system using an image capturing device such as a smartphone camera. More specifically, the present invention relates to a colorimetric inspection sheet equipped with a multi-color reference color patch to overcome non-linear image distortion of a smartphone camera, and a smartphone image correction method utilizing the same. Furthermore, as a specific embodiment, the present invention relates to an integrated colorimetric inspection system that performs optical precision correction and result reading in a single operation by physically attaching a structure including a plasma separation membrane to the upper part of the colorimetric inspection sheet so as to be detachable (removable) in order to eliminate red blood cell interference during whole blood (blood) testing. Background Technology

[0002] Colorimetric point-of-care blood glucose testing, which involves applying chemical reagents to paper strips or cassettes, is widely used due to its low cost. Recently, applications that allow users to obtain results by taking photos with a smartphone camera, instead of visually identifying color changes, have become popular.

[0003] The applicant of the present invention previously filed "Single Shot Correction Technology Using Multicolor QR Codes" (Korean Patent Application No. 10-2026-0081172, Publication No. 10-2026-0074576) as prior art owned by the applicant; however, having proven on their own that such technology has fatal flaws in actual commercial environments, they voluntarily withdrew the application, leaving it as currently known technology. The applicant thoroughly criticizes the aforementioned prior patent, which they devised themselves, as having been technically completely defenseless against physical contamination issues and color distortion in smartphone cameras occurring particularly in whole blood-based precision colorimetric inspection environments, and as having contained fundamental design errors, as follows.

[0004] First, the applicant's aforementioned prior patent committed a logical leap by attempting color correction by relying solely on a 'basic three-color configuration' in which the QR code's location detection marker (Finder), pattern, and background are printed in different colors to acquire shooting information of the QR code details and three reference colors with a single shot. The conventional three-color marker correction method may enable meaningful correction in the environment of a 'general industrial camera' where lighting control is possible and sensor characteristics are uniform. However, 'smartphone cameras' forcibly apply image signal processors (ISPs), aggressive automatic white balance (AWB), and non-linear HDR correction, which vary by manufacturer and model. Therefore, it is mathematically impossible to correct the heterogeneous and multidimensional color distortion profiles unique to smartphones using only three colors. In other words, the three-color correction method of the prior invention overlooked the specificity of the smartphone environment and was merely a crude and primitive level that could not guarantee the quantitative accuracy of colorimetric blood glucose testing at all.

[0005] Secondly, the applicant's prior patent committed a fatal error by completely overlooking the 'spatial external point divergence error,' which is the core of white balancing and spatial color interpolation operations. For optically accurate interpolation, reference points must surround the outermost edge of the color pad, but the outer edge of the test sheet is the area most vulnerable to contamination by blood and user fingerprints. The prior patent adopted only an evasive and incomplete measure of simply placing reference points only on the inside, without a solution for such physical contamination. As a result, it contained a fatal flaw that made commercialization virtually impossible, in which mathematical divergence errors inevitably occurred during correction operations on the outer pads, causing color values ​​to be severely distorted.

[0006] In conclusion, the applicant empirically confirmed the fatal defect of non-linear color distortion of smartphone cameras and divergence of extraneous points caused by physical contamination while attempting to apply the aforementioned withdrawn prior patent (three-color reference point) to actual commercialization in the field of 'whole blood (blood)-based colorimetric blood glucose testing,' which requires extreme precision and contamination control. Accordingly, the present invention was completed by establishing a universal 'multi-color reference point patch and fake reference point generation logic (software)' that overcomes the fundamental limitations of smartphone image correction, and simultaneously combining it with a 'plasma separation membrane detachment structure (hardware)' in a special embodiment that completely solves the physical contamination problem in the blood glucose testing field where this technology was first conceived. The problem to be solved

[0007] The first objective of the present invention is to provide an operational logic system that performs non-linear outer distortion correction optimized for smartphone lens characteristics while avoiding the risk of physical contamination. This is designed to overcome non-linear color deformation (ISP, AWB, etc.) of smartphone cameras that differ from manufacturer to manufacturer and to resolve the spatial mathematical defects of the aforementioned withdrawn prior art patent. Instead of printing physical outer reference points and incurring the risk of contamination, the system virtually generates a 'Fake Reference' by mathematically extending and copying the coordinates of a real, safe, inner multi-color reference point outwardly, and based on this, processes the color pads of the outer area so that they always exist within the reference point fence.

[0008] A second objective of the present invention is to provide a structurally advanced detachable hardware assembly that effectively suppresses red interference of red blood cells occurring when whole blood is injected in a specific embodiment by configuring an upper structure equipped with a plasma separation membrane as a detachable type, thereby removing the upper contaminant entirely after the reaction is completed, and thereby exposing a plasma-based coloration with suppressed red blood cell interference.

[0009] The third objective of the present invention is to further incorporate software logic that dynamically filters extracted defective reference colors and returns to a fallback in preparation for limiting situations (e.g., partial contamination of internal reference points, deterioration of lighting, etc.), thereby ensuring inspection reliability and stability even in various field environments. means of solving the problem

[0010] An integrated colorimetric inspection system according to the first embodiment of the present invention (Independent Claim 1) for achieving the first and third objectives described above comprises: a colorimetric inspection sheet having a structure in which a plurality of multi-color reference color patches are integrally additionally printed around the QR code pattern to overcome the limitations in precise correction of non-linear image distortion inherent to smartphones, wherein a lower support having a multi-color QR code and a color-emitting pad disposed on one surface with physical reference points excluded in the outer area; and a smartphone that captures the sheet once to simultaneously acquire the QR code information and a plurality of reference color information and utilizes them for color correction. Furthermore, an image correction device (Independent Claim 4) and a method (Independent Claim 5) according to another embodiment of the present invention are characterized in that the smartphone captures the colorimetric inspection sheet, extends and copies the coordinates of the inner real reference points outward to generate a fake reference point, and performs spatial color interpolation operations through this to prevent an external point divergence error.

[0011] A structure according to a specific embodiment of the present invention (claim 3) for achieving the second objective described above comprises a structure in which an upper support is laminated on the lower support, the upper support having an intermediate layer, a plasma separation membrane that inhibits the passage of red blood cells in whole blood, and a blood inlet window, and is characterized in that after a blood reaction, the handle of the intermediate layer is pulled to physically detach and remove the upper contaminant structure as a whole, thereby exposing only a clean lower support from which contamination has been excluded. Effects of the invention

[0012] Conventional technology overlooked the unique environmental characteristics of smartphone cameras, which cannot be optically controlled unlike general industrial cameras, and had limitations in that it performed plasma separation and color correction incompletely, resulting in significantly reduced correction accuracy. According to the present invention, the red interference of red blood cells, which was an obstacle during colorimetric blood glucose testing, can be effectively removed by a physical mechanism called a 'detachable plasma separation membrane structure'.

[0013] Furthermore, the present invention completely overcomes the chronic problem of uncontrollable non-linear image distortion in smartphone cameras through the fusion of a multi-color reference patch (hardware) and a sham reference point calculation logic (software). Specifically, by utilizing inner reference points exposed after the upper contaminated layer is physically removed, it overcomes the optical limitations of smartphones, thereby providing an innovative effect that enables precise quantitative readings at the level of medical devices using only a standard smartphone owned by anyone, without the need for expensive dedicated industrial equipment. Brief explanation of the drawing

[0014] FIG. 1 is a plan view of a lower support having a multi-color QR code and a reference color patch printed thereon according to one embodiment of the present invention. FIG. 2 is a conceptual diagram visually illustrating the principle of generating a fake reference according to one embodiment of the present invention. FIG. 3 is an exploded cross-sectional view showing the laminated structure and separated state of a detachable blood colorimetric test strip assembly according to one embodiment of the present invention. FIG. 4 is a block diagram of a smartphone-based color correction and analysis system according to one embodiment of the present invention. Figure 5 is a flowchart of the logic for generating a fake reference point applied to the present invention. Figure 6 is a dynamic filtering flowchart applied to the present invention. Figure 7 is a flowchart of the correction pipeline defense applied to the present invention. Figure 8 is a schematic of the H-Unwrap algorithm for overcoming discontinuities in the circular hue space applied in the present invention. Specific details for implementing the invention

[0015] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. The technical concept of the present invention is not limited to some of the embodiments described but can be implemented in various different forms.

[0016] Referring to FIG. 1, a lower support (140) of a colorimetric test sheet according to one embodiment of the present invention has a multi-color QR code (142) placed in the center. The multi-color QR code (142) provides location recognition and basic color information by including a basic three-color configuration in which a marker (Finder), a pattern (Pattern), and a background (Background) are printed in different colors, so as to obtain QR code details and three reference color shooting information with a single shot. In addition, a plurality of multi-color reference color patches are additionally printed on the periphery (border, etc.) and includes a color-emitting pad (141) that reacts with a sample such as blood. This arrangement of multi-color patches is key to constructing a multi-dimensional color profile to correct non-linear color distortion of a smartphone camera.

[0017] Referring to FIG. 3, a detachable test strip assembly (100) for colorimetric blood glucose testing according to one embodiment of the present invention may be configured as a four-stage structure in which an intermediate layer (130), a plasma separation membrane (120), and an upper support (110) are further stacked on top of the lower support (140).

[0018] At the top of the upper support (110), a blood inlet (111) is formed so that a user can drop blood collected. Whole blood introduced through the inlet (111) passes through a plasma separator (120) located below it. The plasma separator (120) performs the function of physically filtering out red blood cells and allowing plasma components to flow downward.

[0019] An intermediate layer (130) having a separation handle portion (131) is disposed at the bottom of the plasma separation membrane (120). The intermediate layer (130) is temporarily fixed with a weak adhesive only in the non-coloring area of ​​the lower support (140).

[0020] A color-changing pad (141) that changes color upon reaction with a specific enzyme and a multi-color QR code (142) that serves as a standard for color correction are printed or attached integrally to the bottom support (140). When plasma reaches the color-changing pad (141) and the chemical reaction is completed, the user grasps and pulls the separation handle (131) of the middle layer (130). At this time, the upper support (110), the plasma separation membrane (120), and the middle layer (130) fall off together as a single contaminated mass, leaving only the bottom support (140) with blood contamination suppressed.

[0021] With reference to FIGS. 2, FIGS. 4 and FIGS. 5, the process of linking the smartphone (200) system and creating fake reference points of the present invention will be explained. As illustrated in the conceptual diagram of FIG. 2, physical reference points are excluded from the outermost edge of the color pad (141) to avoid physical contamination, and real reference points inside are extended and copied outward to form a virtual reference point fence (350).

[0022] When the camera unit (210) of the smartphone (200) photographs the exposed lower support (140), the system extracts multiple reference color coordinates within the multi-color QR code (142). The reference points may include a white reference point for primary white balancing and a multi-color reference color for secondary color correction. To prevent contamination during handling of the inspection paper, physical reference points are excluded from the outermost (outer) border area of ​​the color pad (141).

[0023] Accordingly, the color correction unit (240) within the smartphone (200) determines whether the color pad (141) is located outside the boundary formed by the actual color reference points on the inside (S415). If it is determined that it is located on the outside, a fake reference point (350) is created by mathematically extending and copying the coordinates of the uncontaminated reference point on the inside to the outside (S425, S426). At this time, the creation of the fake reference point (350) can be implemented by applying a radial extrapolation operation from the center coordinates of the inner reference points toward the corresponding outer region, or by using a mirroring technique that symmetrically moves the outermost actual reference point as an axis to produce virtual color and coordinate data.

[0024] Subsequently, a virtual reference point fence is formed to surround the color pad (141), including the generated fake reference point (350), and a spatial color interpolation operation is performed (S440). The interpolation operation may include at least one of Inverse Distance Weighting (IDW), Radial Basis Function (RBF), or Kriging. This effectively prevents divergence errors caused by the external division point operation, thereby correcting the color of the outer color pad without distortion.

[0025] Meanwhile, referring to FIGS. 6 and FIGS. 7, the color correction unit (240) can further perform a defense logic that dynamically filters the error of the extracted reference color and falls back to linear white balance correction when there is a lack of valid reference colors, thereby ensuring the stability of the operation.

[0026] Referring to FIG. 8, H-Unwrap logic is performed to prevent mathematical discontinuity errors that occur during color space (HSV) calculations (S710~S770). Since red in the HSV color space is distributed across the two extremes of the circular hue angle, near 0 degrees and near 360 degrees, significant color errors occur when color values ​​are simply calculated.

[0027] To suppress this, when calculating the distance between the Hue value of the target color and the Hue value of the reference color, an H-Unwrap operation is applied to normalize the angle with the shortest distance among the ±360-degree offset candidates. As a result, the boundary between 0 degrees and 360 degrees is mathematically connected, enabling stable quantitative reading without color spikes even in red-toned colors. Explanation of the symbols

[0028] 100: Detachable test strip assembly 110: Upper support (top paper) 111: Blood input window 120: Plasma separation membrane 130: Middle layer 131: Separation handle part 140: Lower support (base paper) 141: Color Swatch Pad 142: Multicolor QR Code 200: Smartphone 210: Camera shooting unit 220: QR detection unit 230: Image Normalization Section 240: Color Correction Section 250: Analysis Calculation Department 260: Result Output Section 270: Database Communications Department 300: Remote database 310: Configuration data 320: Color correction matrix 330: Corrected RGB 340: Final result or blood glucose calculation 350: Fake reference point

Claims

Claim 1 An integrated colorimetric inspection system based on a smartphone, comprising: a colorimetric inspection sheet including a multi-color QR code in which a marker (Finder), a pattern, and a background are each printed in different colors to obtain QR code details and three reference color shooting information in a single shot, a plurality of multi-color reference color patches integrally printed around the multi-color QR code to overcome non-linear image distortion of the smartphone, and a color-emitting pad that reacts with a sample to be inspected; and a smartphone for photographing the colorimetric inspection sheet, wherein the smartphone obtains the information details of the multi-color QR code through a single single shot, and simultaneously obtains four or more reference color shooting information including the multi-color QR code and the reference color patches necessary for precise color correction of the photographed color-emitting pad, and utilizes this information for color correction. Claim 2 An integrated colorimetric inspection system according to claim 1, wherein the color correction unit of the smartphone includes logic to maximize the accuracy of optical correction by mathematically extending and copying the coordinates of actual reference points located inside outward for the outer area of ​​the color pad from which physical reference points are excluded to prevent contamination during handling, and performing spatial color interpolation operations on the color pad based thereon. Claim 3 An integrated colorimetric testing system according to claim 1, wherein the colorimetric test sheet comprises: a lower support having a multi-color QR code and a color-developing pad disposed on one surface; an intermediate layer disposed on the lower support and including a separation handle portion that can be pulled to remove; a plasma separation membrane disposed on the upper part of the intermediate layer to inhibit the passage of red blood cells from the injected whole blood; and an upper support having an injection window formed therein for injecting blood, wherein after the reaction is completed, the upper support, plasma separation membrane, and intermediate layer containing remaining contaminants are physically detached and removed by pulling the separation handle portion, thereby exposing only the clean lower support. Claim 4 A colorimetric inspection image correction device comprising: a camera unit that captures a colorimetric inspection sheet to acquire an image; and a color correction unit that extracts color and coordinate information of reference points printed on the inner side of the colorimetric inspection sheet from the acquired image, generates a fake reference point by mathematically extending and copying the coordinates of the inner reference points to a color pad in an outer area from which reference points are excluded to prevent contamination during handling, and performs spatial color interpolation operations on the color pad within a virtual reference point fence including the generated fake reference point to precisely correct the color of the color pad. Claim 5 A method for correcting an image of a colorimetric test sheet using a smartphone, comprising: a step of acquiring an image by photographing a colorimetric test sheet, in which reference points are printed on the inside and color-emitting pads are arranged on the outside, with the smartphone camera; a step of extracting color and coordinate information of the inner reference points from the image; a step of virtually generating one or more fake reference points by mathematically extending and copying the coordinates of the inner reference points to the outer region for the color-emitting pads in the outer region, in which physical reference points are excluded to prevent contamination during handling; and a step of precisely correcting the color of the color-emitting pads by performing spatial color interpolation operations on the color-emitting pads within a virtual reference point fence containing the generated fake reference points. Claim 6 A computer-readable recording medium having a program for executing the method of paragraph 5 on a computer. Claim 7 A colorimetric inspection sheet comprises a lower support having a multi-color QR code and a color-emitting pad disposed on one side, with physical reference points excluded from the outer area to prevent contamination during user handling, wherein the multi-color QR code provides location recognition and basic color information by printing a marker (Finder), a pattern, and a background in different colors to obtain QR code details and three reference color shooting information with a single scan. A colorimetric test sheet characterized by having a structure in which multiple multi-color reference color patches are integrally additionally printed around the QR code to overcome the limitations of precise correction of non-linear image distortion inherent to smartphones using only a three-color composition.

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