On Thu, 7 Nov 2002 08:32:50 +0100 Volker.That@jostra.net wrote:

I've a nice symbol with blue as background color. Now I want to replace the blue with transparency. How can I do that easily ?

Add an alpha channel first (Image->Alpha->Add alpha channel, or via the Layers dialogue). Then use the "magic wand" (it's tool tip says "select contiguous regions") and click somewhere on the background to select everything outside the symbol. Then use Edit->Cut to remove the background. This will only work if the entire area outside the symbol is one colour, though you can change the threshold to select more or less by double-clicking on the wand icon.

If you need to select areas inside the symbol as well, use Select->By color instead; click on a pixel that is the colour of the background, and everything of that colour in the entire image will be selected. Select by colour has a threshold slider too. When everything you want is is selected, use Edit->cut to remove it.

Then go read "Grokking the Gimp" :-)

Regards, K.

-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Karl Auer (kauer@biplane.com.au) +41-43-2660706 (h) http://www.biplane.com.au/~kauer/ +41- 1-6327531 (w)

Hey,

Well you could use the Filters/Colors/Color To Alpha.. as well just take the colorpicker and get the color you want away from the image.

You could also take a look at:

http://www.gimp.org/~sjburges/color_to_alpha/demo/color2alpha.html

For more help.

On Fri, 2002-11-08 at 17:06, Karl Auer wrote:

On Thu, 7 Nov 2002 08:32:50 +0100 Volker.That@jostra.net wrote:

I've a nice symbol with blue as background color. Now I want to replace the blue with transparency. How can I do that easily ?

Add an alpha channel first (Image->Alpha->Add alpha channel, or via the Layers dialogue). Then use the "magic wand" (it's tool tip says "select contiguous regions") and click somewhere on the background to select everything outside the symbol. Then use Edit->Cut to remove the background. This will only work if the entire area outside the symbol is one colour, though you can change the threshold to select more or less by double-clicking on the wand icon.

If you need to select areas inside the symbol as well, use Select->By color instead; click on a pixel that is the colour of the background, and everything of that colour in the entire image will be selected. Select by colour has a threshold slider too. When everything you want is is selected, use Edit->cut to remove it.

Then go read "Grokking the Gimp" :-)

Regards, K.

-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Karl Auer (kauer@biplane.com.au) +41-43-2660706 (h) http://www.biplane.com.au/~kauer/ +41- 1-6327531 (w) _______________________________________________ Gimp-user mailing list
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