I have an image that I removed the background (making it transparent) with this.
But now, it has dark contour that I would like to be smoothly integrated with the background I am adding to it.
I am having a hard time to find a way to smooth just the image contour.
The answer is actually quite simple.
The result wont be 100%, but will be MUCH better than doing nothing.
Just do all work in very high resolution; the most your machine can handle in a affordable time.
The last thing you will do is shrink (scale) the image to the final size you intend to use; that shrinking did the contour smooth integration. I understand the scale options you use may provide good results if you try hard.
PS.: I think this technique is used on 3D games for the same reason; not sure tho; couldn't find yet the proper explanation about it.