If your talking about Photo Shop, sometimes using the background eraser tool takes the background out closer to the edge. To smooth out you could use the smudge tool.

Cheers! Dan.

it may be important to have images in layers at same resolution, if background is at 300dpi, and copy of person is at 72 screen resolution the pixels will appear more o and at lower quality, and the size if small like 3×4 inches, increase to 6×8′ with better resolution,
~you may want to put each person or object in separate layers, to zoom in and erase and smooth edge with smudge/ sharpen drop tool and set sensitivity for pressure to lower amount, and then apply to background as copy for jpg,
..

This is one of the most challenging tasks in Photoshop.

Here are some approaches:

– adjust the tolerance of the magic wand
– try the lasso or magnetic lasso and various featherings
– use the pen tool
– try extract if you have it

None of this is simple so here’s a good source of know-how:

Good luck.
V