Multi-touch sensing system capable of optimizing touch bulbs according to variation of ambient lighting conditions and method thereof

A method of automatically optimizing touch bulbs of a multi-touch sensing system according to a variation of ambient lighting conditions, comprising the steps of:

• using an image capturing module to capture a touch image from a touch panel of the multi-touch sensing system;
• receiving the touch image through a computing module, converting the touch image into a histogram, selecting a grayscale threshold to segmenting the histogram by dichotomy to produce a segmented image, and calculating a between-class variance and a total pixel variance of a pixel class of the segmented image to estimate a separability factor of the pixel class of the segmented image;
• and
• using a processing module to determine whether the separability factor conforms to a predetermined value;
• if yes, then using the grayscale threshold to execute an image binarization on the touch image to produce a binary image, and outputting an operation instruction according to a motion trajectory of each of the touch bulbs in the binary image, or else controlling the computing module to select the grayscale threshold again, and repeating the aforementioned steps until the separability factor conforms to the predetermined value;
• wherein the separability factor SF satisfies relations of:
• SF=VBC(T)/VT=1−VWC(T)/VT and 0≦SF≦1, wherein VBC is the between-class variance of the segmented image, VT is the total pixel variance of the segmented image, VWC is a within-class variance of the segmented image, and T is a set of multi-grayscale thresholds.