Everything you ever wanted to know about transparency but were afraid to ask.

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5
votes
2answers
9k views

Making the background of an image transparent

I have some jpg images and I need for each of them to have a transparent background. I have GIMP as a graphic tool. I need to put them in a web page and I need to see just the main element and have a ...
7
votes
3answers
10k views

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 ...
5
votes
2answers
3k views

Why does my transparent PNG not look good?

I want to convert a JPG to transparent and using GIMP I added alpha layers and transparency same way I make a GIF transparent I converted it to PNG but it doesn't display well when I load it on my ...
2
votes
3answers
139 views

How to extract the black and white components of an image to superimpose it over colored backgrounds

Say I want to create a glowing button for a website. I would like to have the possibility to dynamically change the color of that button by changing the color of it's background. For this I need to ...
2
votes
1answer
576 views

Using GIMP, can you “erase” a color?

I'm presently working on an iOS application and I am attempting to reverse engineer their standard alert dialog window. I have managed to figure out what the alpha value on the background it uses is ...
9
votes
8answers
2k views

Transparency to unpremultiplied RGB + Alpha

I have a transparent layer in Photoshop CS5 (so internally, it's most probably stored as unpremultiplied RGB component plus an alpha component per pixel). Now I want to transform this to an opaque ...
3
votes
5answers
4k views

Replace black background with a transparent background

How can I add transparent background on this image instead of black background, but I also would like to keep the partial transparency effect on some of the particles and particles borders. Could ...
2
votes
1answer
169 views

How to edit an animated gif in gimp to include transparency?

I have an ajax spinner which unfortunately has a white background in the corners. I want to remove the white and make it transparent using GIMP. How can I go about doing that? I tried opening it in ...
1
vote
1answer
90 views

Black-white and grayscale to alpha conversion for images

Is there an utility for converting all black-white and grayscale images from certain folder to the same images with adjusted alpha channel? For example, for pixel (r:50, g:50, b:50, a:0) I would like ...