[Gimp-user] Turn black background into white -- with fuzzy edges

[David Gowers]

Hi Lea,

On Nov 26, 2007 7:29 PM, Lea Wiemann <LeWiemann at gmail.com> wrote:
> Hi,
>
> I'd like to turn a black background into white, or transparency (in
> which case it should look cut if displayed on a white background).  My
> practical use case is photos of objects with black backgrounds that I'd
> like to improve for Wikipedia.  The problem is that the boundary between
> background and object is usually fuzzy.
>
There is no real good way to do this for arbitrary photos; For this
particular photo, the best result I could achieve was by:
1. Use magic wand to select background
2. Convert the selection to a path, and convert the path back into a
selection (this has the effect of smoothing the edges of the
selection.. PoTrace produces better results than the GIMP sel2path
plugin, I assume you have to work with standard GIMP plugins only
though.)
3. Fill with white.

The result of applying this is attached.

Notably this shows a smooth black outline around the object. The
method I tried to convert white to black without causing an outline
effected the overall color of the object too much instead.  (this
method was: 1. layers->transparency->color to alpha (select black); 2.
flatten with bgcolor = white.)
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