Precision luxmeter methods for digital cameras to quantify colors in uncontrolled lighting environments
In one embodiment, a diagnostic system for biological samples is disclosed. The diagnostic system includes a diagnostic instrument, and a portable electronic device. The diagnostic instrument has a reference color bar and a plurality of chemical test pads to receive a biological sample. The portable electronic device includes a digital camera to capture a digital image of the diagnostic instrument in uncontrolled lightning environments, a sensor to capture illuminance of a surface of the diagnostic instrument, a processor coupled to the digital camera and sensor to receive the digital image and the illuminance, and a storage device coupled to the processor. The storage device stores instructions for execution by the processor to process the digital image and the illuminance, to normalize colors of the plurality of chemical test pads and determine diagnostic test results in response to quantification of color changes in the chemical test pads.
1. A method for a digital photograph, the method comprising:
capturing a digital photograph of a predetermined colored object with a digital camera, the digital photograph including metadata, wherein the predetermined colored object includes a reference color bar and the digital photo includes the reference color bar;
extracting perceived colors of the predetermined colored object from the digital photograph, including:
extracting perceived colors of the reference color bar from the digital photograph; and
normalizing the perceived colors of the reference color bar into normalized colors of the reference color bar, including:
determining an inverse color correction factor for the reference color bar from perceived colors of the reference color bar under known illuminance and lighting conditions; and
wherein the normalizing of the perceived colors of the colored image into normalized colors of the colored image is in response to the inverse color correction factor; and
in response to the perceived colors of the reference color bar, the normalized colors of the reference color bar, and the metadata of the digital photograph, determining a nearest illuminance within a set of illuminances under which the digital photograph was captured.
2. The method of claim 1 , wherein the extracting perceived colors of the predetermined colored object from the digital photograph includes
detecting one or more features of the predetermined colored object in the digital photograph; and extracting a perceived color of the one or more features of the predetermined colored object from the digital photograph.
3. The method of claim 2 , wherein the predetermined colored object is a diagnostic instrument and the one or more detected features include one or more chemical test pads.
4. The method of claim 3 , further comprising:
selecting one color trajectory from a set of color trajectories for a test in response to the nearest illuminance, wherein the set of color trajectories are respectively associated with the set of illuminances;
comparing the selected color trajectory with normalized colors of one chemical test pad to quantify the test of a biological sample applied to the chemical test pads; and
communicating results of the quantification of the test.
5. The method of claim 4 , wherein the test is for a concentration of analyte in the biological sample.
6. The method of claim 1 , further comprising
normalizing the perceived colors of the predetermined colored object into normalized colors of the predetermined colored object; and
wherein the determining of the nearest illuminance within the set of illuminances under which the digital photograph was captured is further in response to the normalized colors of the predetermined colored object.
7. A method for a digital photograph, the method comprising:
capturing a digital photograph of a predetermined colored object with a digital camera, the digital photograph including metadata, wherein the predetermined colored object includes a reference color bar and the digital photo includes the reference color bar;
extracting perceived colors of the predetermined colored object from the digital photograph, including:
extracting perceived colors of the reference color bar from the digital photograph;
normalizing the perceived colors of the reference color bar into normalized colors of the reference color bar;
normalizing the perceived colors of the predetermined colored object into normalized colors of the predetermined colored object; and
in response to the perceived colors of the reference color bar, the normalized colors of the reference color bar, the normalized colors of the predetermined colored object, and the metadata of the digital photograph, determining a nearest illuminance within a set of illuminances under which the digital photograph was captured.
8. The method of claim 7 , wherein the extracting perceived colors of the predetermined colored object from the digital photograph includes
detecting one or more features of the predetermined colored object in the digital photograph; and extracting a perceived color of the one or more features of the predetermined colored object from the digital photograph.