A New Approach to Locate the Gallbladder from Ultrasound Image Using Intensity Stretching and SOM-based Color Quantization

In the ultrasound image, the gallbladder has a wide variety of shape, type, size, and slope, so the existing researches into contour-based gallbladder detection cannot be applied to the various types of gallbladder. Therefore, in this paper, we present a new approach to locate the gallbladder from ultrasound image using ends-in search stretching and self organizing map (SOM)-based color quantization. We use the ends-in search stretching technique to emphasize the difference in brightness among the structures, and SOM-based color quantization is used to classify pixels into the gallbladder and gallbladder wall. After SOM-based color quantization, we extract gallbladder candidates. To verify the gallbladder candidates, we define five morphologic characteristics-based rough conditions. We experiment using 30 ultrasound images. Experiment results shows the proposed method locates the gallbladder excellently despite gallbladders have a variety of shapes.