The more encoding steps, the less intense and narrower the artifacts. The first axial image is a phantom containing water, surrounded by air. The image was encoded 128 times in the horizontal direction and 256 times in the vertical direction. Note the prominent light and dark line along the sides that fade as they approach the top and bottom of the phantom. The second image was encoded 256 times in both directions.
Minimal artifact is seen uniformly around the periphery of the phantom.
The diagram below shows the Gibbs effect resulting from a Fourier transformation of a sharp change in image intensity.