Arteries : oxygenated hemoglobin;
Veins: deoxygenated hemoglobin.
Deoxygenated hemoglobin absorbs light (700-1400 nm) => NIR.
Parts in which the veins lie will appear darker than the other parts.
Preprocessing
Median Filter: noise reduction, by ranked the neighbouring pixels according to brightness (intensity) and the median value becomes the new value for the central pixel.
Otsu’s Thresholding: select a suitable thershold to find the palm region.
ROI Segmentation
