gimp - Add transparency to an existing PNG

I'd like to use this image on a web site.

What I need to do is change the background from black to transparent, so I can use the arrow on my site maintaining the page background.

I used Gimp to convert the image to .png, but how do I proceed now?

Answer

GIMP's Color to Alpha tool is very handy if you know how to use it, and this task seems particularly well suited for it:

1. Open the image in GIMP, and change it to RGB color mode if necessary.


2. Select Layer → Transparency → Color to Alpha...


3. Select black (#000000) as the color to make transparent.


4. Click "OK".


5. Save the resulting image in PNG format: