English: Part of a series of images to compare and contrast the levels of spatial aliasing that can result when an image that contains some strong spatial frequencies is digitally rescaled. An image of an 1801 engraving of King's College Chapel, Cambridge was used as a test object, and resized to 50% using different filters and different programs.

The image on this page was resized to 50% using GIMP with the most basic "no interpolation" option -- i.e. merely retaining every other pixel. The interaction between this and spatially repeated structures in the engraving (see WP on spatial aliasing) has resulted in a highly visible Moiré banding pattern becoming apparent in the sky, the clouds and the building on the right.

Other images in the series look at the results of using various available lowpass filters to try to minimse or suppress such artefacts.