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

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 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

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>

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