A method for obtaining a point-of-collection, selected quantitative indicia of an analyte on a test platform, comprising: providing a modular, colorimetric reactive test platform having a test region (202-205, 1008) and a calibration region ; providing an analyte to be tested on the test region of the modular, colorimetric test platform, wherein the test region is adapted to enable a colorimetric reaction to the analyte; obtaining a color image of the test region containing the analyte and the calibration region; selecting an array of pixels in each of the color images of the test region containing the analyte and the calibration region; determining a median RGBA color value for each of the arrays of pixels; converting the median RGBA color value for each of the arrays of pixels to a respective Hue-Saturation-Luminosity (HSL or HSV) test color space value and a HSL or HSV calibration color space value; wherein an indicia of the analyte is one of pH, cholesterol and vitamin D, and wherein the HSL or HSV test color space value and the HSL or HSV calibration color space value are each one of a value channel, a hue channel or a combination of a hue channel and a saturation channel, the value channel being used for the indicia of vitamin D, the hue channel being used for the indicia of pH, and the combination of the hue channel and the saturation channel being used for the indicia of cholesterol; providing a calibration indicia that relates a selected quantitative indicia of the analyte to a characteristic of the HSL or HSV calibration color space value; and associating a median HSL or HSV test color space value with the HSL or HSV calibration color space value to determine the selected quantitative indicia of the analyte. providing a modular, colorimetric reactive test platform having a test region (202-205, 1008) and a calibration region ; providing an analyte to be tested on the test region of the modular, colorimetric test platform, wherein the test region is adapted to enable a colorimetric reaction to the analyte; obtaining a color image of the test region containing the analyte and the calibration region; selecting an array of pixels in each of the color images of the test region containing the analyte and the calibration region; determining a median RGBA color value for each of the arrays of pixels; converting the median RGBA color value for each of the arrays of pixels to a respective Hue-Saturation-Luminosity (HSL or HSV) test color space value and a HSL or HSV calibration color space value; wherein an indicia of the analyte is one of pH, cholesterol and vitamin D, and wherein the HSL or HSV test color space value and the HSL or HSV calibration color space value are each one of a value channel, a hue channel or a combination of a hue channel and a saturation channel, the value channel being used for the indicia of vitamin D, the hue channel being used for the indicia of pH, and the combination of the hue channel and the saturation channel being used for the indicia of cholesterol; providing a calibration indicia that relates a selected quantitative indicia of the analyte to a characteristic of the HSL or HSV calibration color space value; and associating a median HSL or HSV test color space value with the HSL or HSV calibration color space value to determine the selected quantitative indicia of the analyte. <EOS>