Figure 1. What are voxels? Shown here are surface renderings of 3D brain images. On the left is a high-resolution image, with small (1 mm x 1 mm x 1.5 mm) voxels; the voxels are too small to see. On the right is a low-resolution image of the same brain, with large (7 mm x 7 mm x 10 mm) voxels, clearly showing the voxels making up the image.