Step 1: Overview
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.
Step 2: Get A Picture
When you're ready, open th image In Photoshop.
Step 3: Create A Quick Mask
It's kinda confusing but:
Tinted Red In Quick Mask Mode
Not Selected in Normal Mode
Black in Alpha Channel When Created from Selection
Tranparent in SL
Not Tinted Quick Mask Mode
Selected in Normal Mode
White in Alpha Channel When Created from Selection
Not Tranparent in SL
For this step just remember that white is opaque and black is transparent and transparency shows up as a red tint on your image. Shades of grey will become semi-transparent and will only be slightly tinted red.
Step 4: Create an Alpha Channel
Step 5: Save As Targa
Step 6: Upload into Second Life
Step 7: Tips & Closing Comments
You can invert a selection with Shift+Ctrl+I or you can invert pixels with Ctrl + I.
Don't forget, there are always the lasso and magic and selection tools to play with.
If you are trying to create a flat object, I highly recomend applying a full alpha texture to the object first, then dragging your alpha textures to the face you want to apply it to.
236c39da-3bf7-25ac-b2d7-867d66616420 is a full alpha texture.
If you use a script to apply a texture or texture animation to a prim, delete it after the texture or texture animation is set. Floating text, particle systems, and animated textures are properties of a prim and persist after the script that sets them is deleted. No need to have a script running to set something that is already set.
If you want your texture to look good in SL, choose your texture height and width by powers of 2: 2, 4, 8, 16, 32, 64, 128, 256, & 512. 512x512 is usually the largest size you'd want for a texture. Bigger than that and it will take forever to load.
I hope you found this information useful, now go make SL beautiful. :D