Intensity projection differs from shaded volume rendering in two important ways:

1. Rather than performing a color mapping using an opacity curve, voxels values are mapped directly to grayscale intensity values. Window-leveling is still performed, however, in order to adjust the brightness and contrast of the image.
2. Instead of displaying the nearest voxels to the viewer (which essentially creates a surface rendering) the algorithm examines all voxels and, based on some other criteria, decides which one to display. This means that nearby objects do not necessarily occlude more distant objects.

The 3mensio SDK supports two different approaches to deciding what to display. The approach shown in this video takes the maximum of all the voxel values lying under a given pixel, and is known as maximum intensity projection (MIP). This emphasizes high density structures and causes them to show up in the rendered image even if they are occluded by nearer structures. It is therefore often used for examining bones or contrast-enhanced vessels.

Another supported approach is to take the average of all the voxels lying under each pixel, which is known as average intensity projection (AIP). It produces images similar to conventional X-ray images, but with the added advantage that they can be manipulated in real time. The video that illustrates slabbing also shows AIP in action.