plib-users

[Plib-users] Transparent Background

[Alexander R. <a_r...@in...>]

Hi,

I have some pictures I like to use as explosion, galaxies, background
image etc.,
but I need their background to be transparent, instead of color black.

I did load one of those into gimp, and gimp showed me that the picture
had
no alpha channel, and that the background was indeed black not
transparent.

OK - I managed to add a alpha layer to the picture and could erase parts
of
the picture from black to transparent with the eraser but - parts of the
picture
are too fine/delicate for that tool, I'd better like to say something
like
"Hey gimp, please fill from here with transparency" or
"Hey gimp, please replace color black with transparency" but
I didn't find it (gimp newbie). Comments?
I managed to fill with some other color, but not with transparency.

Or is there an other batch-tool, that converts color black to
transparency for all
images I like?

Or can I say GL/plib to load an object/image an declare color black as
transparent?


Alex

-- 
                   Alexander Rawass
          Email: ale...@us...
   Project Homepage: http://kobayashimaru.sourceforge.net
...but some day you'll be a STAR in somebody else's SKY...

Re: [Plib-users] Transparent Background

[Steve B. <sjb...@ai...>]

Alexander Rawass wrote:

> I have some pictures I like to use as explosion, galaxies, background
> image etc.,
> but I need their background to be transparent, instead of color black.
> 
> I did load one of those into gimp, and gimp showed me that the picture
> had
> no alpha channel, and that the background was indeed black not
> transparent.

In GIMP, do this:

  1) Add an alpha channel.
  2) Under the 'select' menu, choose 'Select by colour'
  3) Click on some nice large black area - it'll select all the black
     in the image and you can wipe it out (to transparent) simply by
     clicking on 'cut' in the 'Edit' menu.
  4) By playing with the slider in the select/by-colour menu, you
     can control just how close to the colour of the pixel you
     clicked on will be selected.
  5) If that doesn't work well (eg there are also other dark areas
     that you want to keep - but you still have a dark 'halo' around
     the image) - then do a 'grow' in the select menu to increase the
     'thickness' of the selection before you hit 'cut'.
  6) UNDO (control-Z) can be your friend!  Use it!

> Or can I say GL/plib to load an object/image an declare color black as
> transparent?

No - I think GIMP is good enough to do this right.

-- 
Steve Baker   HomeEmail: <sjb...@ai...>
              WorkEmail: <sj...@li...>
              HomePage : http://web2.airmail.net/sjbaker1
              Projects : http://plib.sourceforge.net
                         http://tuxaqfh.sourceforge.net
                         http://tuxkart.sourceforge.net
                         http://prettypoly.sourceforge.net

Re: [Plib-users] Transparent Background

[Alexander R. <a_r...@in...>]

Hi,

Steve Baker wrote:

> > I did load one of those into gimp, and gimp showed me that the picture
> > had
> > no alpha channel, and that the background was indeed black not
> > transparent.
> 
> In GIMP, do this:

Thanks , I did it that way.

But I have to say, my mouse walked a mile ;-)


Alex

-- 
                   Alexander Rawass
          Email: ale...@us...
   Project Homepage: http://kobayashimaru.sourceforge.net
...but some day you'll be a STAR in somebody else's SKY...