This will guide you step-by-step on how to make textures with transparency for Second Life using Adobe Photoshop CS. It includes tips on how to avoid blurry white outlines and a little info on masks and alpha channels.

Step 1: Overview

Making textures with alpha channels is pretty easy once you get the hang of it. There are three basic steps: Selecting your pixels, making an alpha channel from those pixels, and saving the image as a targa file with alpha channels.

Confused as to what an alpha channel is? Let me tell you a little bit about channels, masks, and transparency. An image is like a matrix of pixels. Each pixel has its own set of values for how to display it, which is usually its color. If you've ever played with a crystal prism, you know that most light can be broken down into different colors. Pixel colors are usually stored in terms of the amount of red, green, and blue. Each of these colors can be considered a "channel" or a sub-version of the image. In red-green-blue channels values can range from 0 to 100%. So each channel is a monochrome version of the image varying on how much of that color is in the image.

To complicate matters further, we can add more channels. This is useful if we want to add more information to a pixel. An alpha channel is another greyscale image that says how opaque that pixel is. White is fully opaque and black is fully transparent.

One of the great features of Photoshop is it's ability to juggle selections to channels back and forth. A selection could be considered a temporary channel. In fact the quick mask feature lets you "paint" a selection and toggle it back and forth from a temporary alpha channel to an active selection.

This tutorial will detail how to create a selection using quick mask, and how to save it as an alpha channel.
lol awesome instructable, but what is with your avatar! :p lol. anyway, all i really needed is 2 know what 2 save file extension as, since i have all the textures 2 build a ferrari, and i made them all, but i didnt know what 2 save them as. Yo i'm dwarfzilla
Does an exported TIF with transparency (by changing mode in photoshop to Bitmap) work?
it only works as a .TGA file
hi being a new user of Photoshop, and don't know a thing lol, i tyvm, keep them coming :)
THe list of powers of 2 is wrong; that should be 2, 4, 8, 16, 32, 64, 128, 256, 512. 1024 and 2048 are also possible sizes, but should usually be avoided; they take FOREVER to load.
I'm bad at math. I can't double numbers in my head. XP Thanks for pointing that out.

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More by Aster:Look Script For Cutouts How to use Photoshop to Create Textures With Alpha Channels for Second Life 
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