RasterView is a CUPS, PWG, and Apple raster file viewing application.
It basically allows you to visually evaluate raster data produced by any of the standard CUPS RIP filters (cgpdftoraster, imagetoraster, pdftoraster and pstoraster). It is normally used to either test those filters or look at the data that is being sent to your raster printer driver.
This is a companion discussion topic for the original entry at https://appimage.github.io/rasterview/