If an Amiga compatible operating system (MorphOS on, for example, a compatible PPC Mac) could be an option, there's a marvellous image processing program included in the OS.
ShowCase is the best program you can find for digital photo handling on Amiga compatibles, I've been using it for years for my photo processing.
It has good selectable resizing algorithms, horizon can be straightened in photos, it has sharpening, noise reduction, etc. image processing options, lossless JPEG transformations, automatic rotation of digital camera images, thumbnail creator, batch processing, internal album manager with Picasa exporting (not sure if it still works though, did Google drop Picasa?), and many other features aimed for digital photo/camera processing.
