Thresholding Demonstration

This scan shows the chest, with the spine at the top, and the aorta, with a balloon-like aneurism.

Scans come in as arrays of voxels, each of which is a value in the range 0 to 255.

Surgeons can look at these on computerised displays and interpret them. We want computers to be able to automate, or semi-automate, this expert task.

We want the computer to be able to pick out the organs and vessels in the picture by itself. One technique that can help is thresholding. If a voxel has a `high' intensity, we colour it white, and otherwise we colour it black.

We set a threshold in the range 0...255 and use this to convert the original image to a black/white picture.

Try it here - distill the main aorta from this scan of the chest