Re: [Gimp-user] Colour - Alpha

2003-09-07 Thread Sven Neumann
Hi,

chris.danx [EMAIL PROTECTED] writes:

 Is it possible to make all pixels of a given colour transparent?

Yes, select by color and clear that selection. There is a tool to
select pixels by color.


Sven
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Re: [Gimp-user] Colour - Alpha

2003-09-07 Thread David Neary
chris.danx wrote:
 Hi,
 
 Is it possible to make all pixels of a given colour transparent?  I've 
 just started playing with the gimp and am a bit stuck.  Basically I want 
 to duplicate a selection in the background layer, put it in a 
 transparent layer with only the non-white pixels opaque.  Maybe there's 
 a better way to do this?

Add layer mask, Select by colour on layer, activate mask, fill
selection with black. 

Or, select by colour, quickmask, copy the mask (in the channels
dialog), and apply that mask as a layer mask.

Cheers,
Dave.

-- 
   David Neary,
   Lyon, France
  E-Mail: [EMAIL PROTECTED]
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Re: [Gimp-user] Colour - Alpha

2003-09-07 Thread Jeff Trefftzs
On Thu, 2003-09-04 at 12:59, chris.danx wrote:
 Hi,
 
 Is it possible to make all pixels of a given colour transparent?  I've 
 just started playing with the gimp and am a bit stuck.  Basically I want 
 to duplicate a selection in the background layer, put it in a 
 transparent layer with only the non-white pixels opaque.  Maybe there's 
 a better way to do this?

Sorry for the delay - it's now Sunday and this post only just arrived.

Short answer:  Image/Select/Select by Color  should do it.  If you want
to make the selected (or not selected) pixels transparent, make sure you
have an alpha channel.  You can't do this on the background layer.

An alternative is the Image/Filters/Colors/Color_to_alpha plug-in.

Experiment with both of these and see what works for you.

-- 

--Jeff

Jeff Trefftzs [EMAIL PROTECTED]
http://www.tcsn.net/trefftzsHome Page
http://gug.sunsite.dk/gallery.php?artist=68 Gimp Gallery
http://trefftzs.topcities.com/  Photo Gallery 

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