IrfanView is a Windows app which can change the size with interpolation.
On the Amiga
PicShow does a similar job, but not in batch mode, though.
SuperView is another Amiga application which can do any kind of image manipulation.
Of course you can use the Amiga apps both on a real Amiga and in an Amiga emulation, given that the emulation has a complete AmigaOS installed.
However, reducing the image size by a factor of 100 always looses details, although with interpolation it looks much better than without.
Bye,
Thomas