Figure 3From: An automated method for analysis of microcirculation videos for accurate assessment of tissue perfusion Method of validating vessel pixels. A vessel candidate pixel is labeled as p in Figure 3. The output of EDT is used to find the nearest background pixel to p, b p . For each of the 24 neighboring pixels in the 5 × 5 neighborhood around p, n 1 − n 24, the nearest background pixel is found, b n , and used to calculate the diameter, angle and contrast ratio values. The b n1-24 having the greatest distance from b p is considered the opposite background pixel, b max , and the distance is the diameter, d, of the vessel. If d is less than P d then the angle, θ, is calculated between b p , p and b max and is used to validate the distance by ensuring that b p and b max are on opposite sides of the vessel (θ must be greater than P θ ). Finally, the contrast ratio between p and b max is calculated and if greater than P c , the candidate pixel is considered a valid vessel pixel. Since the found vessels lie along the center of the actual vessel, the vessel must be reconstructed using the found diameter and pixel locations.Back to article page