1. A method for determining a concentration of a biological target, the method comprising: capturing an image of a ticket including the biological target; extracting a region of interest from the captured image; detecting a target from the extracted region of interest comprising a multi-level target detection based on a concentration of the target, the multi-level target detection including: detecting a target with a high concentration by applying an edge detection and circular contour analysis to extract the target with a high concentration; detecting a target with a medium concentration by analyzing a local grayscale distribution to separate a target area with circular shape background; and detecting a target with a low concentration by extracting partial circular shape features from the background; electronically computing intensity of the target in the region of interest; and determining the concentration of the biological target according to the computed intensity.