The J Suite
Jclean, Jcut and Jsize
This page up to date on: 15 Nov 2019
These three “non-commercial free use” programs are J. David Barrow's suite of JPEG manipulation applications from 2002: Jclean v.400 (97KB), Jcut v.301 (110KB) and Jsize v.101 (9KB). These programs operate on JPEGs in such a way as not to re-sample the images. Jclean will clean JPEGs (such that they load into more programs on RISC OS) and it enables you to manipulate the comments and suchlike in the file; Jcut allows you to crop JPEGs along byte (?) boundaries without loss of detail, and JSize allows you to change DPI settings. You may want/need to drop in a new version of jpegtrans kindly updated by Chris Johnson and here is a later version of the Jpegtools than hosted here http://www.riscos.info/packages/GraphicsDetails.html#libjpeg-progs.