[Gimp-user] removing layer area

2010-05-10 Thread bob
Hi all.

I'm trying to edit an jpg image I've downloaded from the net.
This image:

http://creativenerds.co.uk/wp-content/uploads/2009/04/twitter-icos.jpg

As you can see, the image has a white background.

I want to isolate one of the illustrations and remove the white background.

First I use the scalpal tool to isolate one of the illustrations. Then I use
either the select tool or the erasor to remove the white. Instead of getting
transparent area as a result, I get a grey.
(What is happening here)

To get around this, I first save the image as a png, then give the image a
background layer with a random colour, save the image as an xcf and close the
image. Then I open the xcf. 
Again, I try to erase the white in order to get a transparent area. Again, I
get an grey as a result.

Obviously, I'm running into the boundaries of my understanding of image
formats here.

I'd love to know why I'm getting these results.

I'd also like to know how I can remove the white area and get transaparency
without closing and re-opening the image.

-- 
bob (via www.gimpusers.com)
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Re: [Gimp-user] removing layer area

2010-05-10 Thread Jozef Legény
Also, consider using either the fuzzy select tool (magic wand) instead of
scissors. You can fiddle with the threshold settings to get good results.

GIMP also provides a handy function in the Color menu called Color to
alpha, by default it does exactly what you want to do (but will also remove
some white under your icons, so do the selection first anyways).

On Mon, May 10, 2010 at 08:09, Andrew and...@alangdondavies.es wrote:

 bob wrote:
  Hi all.
 
  I'm trying to edit an jpg image I've downloaded from the net.
  This image:
 
  http://creativenerds.co.uk/wp-content/uploads/2009/04/twitter-icos.jpg
 
  As you can see, the image has a white background.
 
  I want to isolate one of the illustrations and remove the white
 background.
 
  First I use the scalpal tool to isolate one of the illustrations. Then I
 use
  either the select tool or the erasor to remove the white. Instead of
 getting
  transparent area as a result, I get a grey.
  (What is happening here)
 
  To get around this, I first save the image as a png, then give the image
 a
  background layer with a random colour, save the image as an xcf and close
 the
  image. Then I open the xcf.
  Again, I try to erase the white in order to get a transparent area.
 Again, I
  get an grey as a result.
 
  Obviously, I'm running into the boundaries of my understanding of image
  formats here.
 
  I'd love to know why I'm getting these results.
 
  I'd also like to know how I can remove the white area and get
 transaparency
  without closing and re-opening the image.
 
 
 Looks to me as though the image has no transparency in it.

 Menu: Layer  Transparency  Add alpha channel

 HTH

 Andrew
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Re: [Gimp-user] removing layer area

2010-05-10 Thread Rob Antonishen
I have a script http://ffaat.pointclark.net/incoming/scripts/transbg.scm

The combines select by colour and colour to alpha with a few
parameters to simplify this process.

-Rob A
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Re: [Gimp-user] removing layer area

2010-05-10 Thread Pere Pujal i Carabantes
El dl 10 de 05 de 2010 a les 08:02 +0200, en/na bob va escriure:
 Hi all.
 
 I'm trying to edit an jpg image I've downloaded from the net.
 This image:
 
 http://creativenerds.co.uk/wp-content/uploads/2009/04/twitter-icos.jpg
 
 As you can see, the image has a white background.
 
 I want to isolate one of the illustrations and remove the white background.
 
 First I use the scalpal tool to isolate one of the illustrations. Then I use
 either the select tool or the erasor to remove the white. Instead of getting
 transparent area as a result, I get a grey.
 (What is happening here)
 
 To get around this, I first save the image as a png, then give the image a
 background layer with a random colour, save the image as an xcf and close the
 image. Then I open the xcf. 
 Again, I try to erase the white in order to get a transparent area. Again, I
 get an grey as a result.
 
 Obviously, I'm running into the boundaries of my understanding of image
 formats here.
 
 I'd love to know why I'm getting these results.

JPG don't has transparencies, so GIMP opens them withouth alpha channel.

 
 I'd also like to know how I can remove the white area and get transaparency
 without closing and re-opening the image.
 

Add alpha channel as suggested, then use the magic wand to select the
wite then edit-cut and you are done.

But if you want more quality, then zoom to 800 or more, look at the
white in the edges and continue adding a layer mask (transfering the
alpha channel already created, then carefully paint the edges of the
object in the main layer with the same color as the neighbour pixels, so
the wite don't show in the edges.

Hope this helps.
Pere

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