This freeware tool creates cropped thumbnails from an input file which can be either a local file (jpg, gif, or png) or a URL. Images are resized to fit inside a specified thumbnail size, with any “overhang” being cropped off (rather than there being empty space used to fit it). It’s primarily intended to be called from other tools but can be run from the command line.
Here’s the embedded help (which you can get by running it without input):
Here’s some sample usages:
cropthumb bigimage.gif thumb.jpg
This crops bigimage.gif down to an 80% quality 150×150 jpg thumbnail called thumb.jpg.
cropthumb c:\temp\bigimage.jpg c:\temp\bigimage.jpg 100 200 50
This crops c:\temp\bigimage.jpg to a 100×200 thumbnail and saves it over top of the original input file at 50% quality. The only limitation on paths (and I guess URL references) is that you can’t have spaces in them because I didn’t write a real parsing routine.
cropthumb https://www.server.com/image.jpg thumb.jpg
This downloads https://www.server.com/image.jpg and saves it to a 150×150 pixel thumbnail locally as thumb.jpg.