Sprites and Transparency at Run-time

My game will allow the player to provide their own Avatar image. Is there an easy way (without reprocessing the image) to make a specific color in the Sprite transparent?

Basically I want to say "What ever color is at 0,0 is the Transparent color".

 

Yes, there are free chroma key shaders which you could modify so it just looks at the pixel color at 0, 0 instead of using the color passed into the material.
http://forum.unity3d.com/threads/chroma-key-in-unity-5.359119/ for example

But why not just use alpha?

 

I'm new to Unity, so maybe I'm not sure what you mean.

 

Generally if you want transparency in an image you just have the image have transparency using the alpha channel instead of making a specific color transparent.

 

That's kind of what I figured what you were getting at. The issue here is, that I won't be the one providing the images. They could come to me in JPG, PNG, etc... formats. The images will be loaded dynamically. Was hoping there was something built into Unity that would say "Make this color transparent'.

It looks like I'll just need to re-process the image once it's been sent to me to deal with it that way.

 

I mean, if 'adding an extra 33% to the size of your data' isn't a reason not to, I'm not sure what is.

 

Even in 2015, 'adding an extra 33% to the size of your data' wouldn't have mattered.