Large size (e.g. 4000x3000 pixels, 4MB) digital camera pictures should be converted to optimal (HD TV quality) files with 1920x1080 pixels and 72 dpi. A 1920x1080 'frame' can be moved over the 4000x3000 raw picture size. And/or the 4000x3000 can be 'squeezed' to match the 1920 width of the HD-size frame to create the target HD TV 1920x1080 pixels 72 dpi files.
What are the most effective steps to realise this task with GIMP? If there are multiple (100+) files to convert, is there some 'automation' with manual intervention possible?
The reason for this is to convert digital camera pictures into 'slideshows' for presentation on a flat-screen 16:9 TV with HD quality pictures of optimal quality/size.
Either you crop (but this cannot be automated, proper cropping will depend on picture, or you resize.
Resize can be automated (but there are vastly simpler photo management tools for this, like XnView or IrfanView), but any device displaying pictures in a TV can resize them on the fly, so this serves little purpose?.