It stands for Precision Raster Image Convolution Engine and is an
application that is capable of filtering and processing images. It is
available on both GNUstep (thus linux, netbsd, freebsd, openbsd,
solaris) and MacOSX (tested from 10.2 Puma and up). It is multi-document
based and can open all standard images supported by GNUstep (tiff, png,
jpg to cite some). It is capable of doing standard operation like
crop&scale or brightness&contrast as well as more advanced operations
with frequency-based filters or median filters or customizable edge tracing.