Method for calibrating a camera of a mobile device for detecting an analyte in a sample

A detection method for detecting an analyte in a sample using a camera of a mobile device, the method comprising:

• a) capturing an image of an object using the camera, wherein during the capturing an illumination source of the mobile device is turned on;
• b) determining from the captured image a first area in the image which is affected by direct reflection of light originating from the illumination source and reflected by the object, wherein a histogram analysis of the image is used to identify the first area;
• c) determining a second area in the image which does not substantially overlap with the first area and returning the second area as a target area;
• d) providing a test strip for detecting the analyte in the sample, the test strip having a test field comprising at least one test chemical for performing an optical detection reaction in the presence of the analyte;
• e) applying a sample to the test field of the test strip;
• f) providing visual indication for the user to position the test strip relative to the camera to thereby locate the test field at least partially in the target area;
• g) capturing an image of the test field using the camera, wherein during the capturing the illumination source is turned on;
• and
• h) determining, from the image captured in step g), the analyte concentration in the sample.