No automatic boundary tracer in Irfanview that I know of. I use Photoshop if I need that (obviously not freeware).
How do you use boundary tracer cropping in PS? I have a trial version of CS2. Thanks.
If the "boundary tracer" is what I think it is then in Photoshop it is called "Magic Wand Tool". Like, say you had a solid black square on a white background. If you clicked the square with the Magic Wand Tool" then it will automatically put a "marching ants" outline around the black box, by automatically recognizing the boundary between the white and black. It makes it easy to separate a main object from its background, though it isn't a cropping tool in and of itself.
If by "boundary tracer" you mean something different, then I don't know what to tell you. Nearly any image editing program (aside from MS Paint) will have a cropping tool where you can just drag a rectangular outline around the area you want to keep and then hit enter or whatever to crop it down to the size of the boundary you made. Like I said earlier, I use Irfanview for that sort of cropping (even though Photoshop can do it as well) because it is so small and opens instantly, as fast as opening something like Notepad. Plus you don't have to actually select a cropping tool in Irfanview, you just click and drag your mouse pointer on the image and it creates the boundary. Ctrl+Y completes the crop.