Fig. 1

Process Schematic. Semi-automated Measure of Mean Linear Intercept. The initial lung field is converted to an 8-bit image, then Huang thresholding binarizes the image to denote airspace and lung. Semi-transparent test lines are then added to the image, and color thresholding is used to isolate discrete chords based on pixel color. The chord indicated by arrow 1 represents a genuine chord, whereas the chord indicated by arrow 2 represents a chord that would be excluded as a false intercept (its true length is uncertain)