How to use Photoshop to Create Textures With Alpha Channels for Second Life

Step 3 Create A Quick Mask

Press Q to toggle between normal and quick mask modes. The current mode is displayed on the Tools menu near the bottom. A white square with a white circle in it is normal mode and a grey square with a white circle is quick mask mode. Enter quick mask mode. Essentially starting off everything is selected so the mask is "white" and clear. Use the paint bucket tool to fill the mask with black. This should tint the image red. All tinted pixels are not selected and will become transparent when we make our alpha channel. Using the paintbrush tool or your tool of choice, paint the parts of the image you want to be non-tranparent white.
It's kinda confusing but:

Black:
Masked
Tinted Red In Quick Mask Mode
Not Selected in Normal Mode
Black in Alpha Channel When Created from Selection
Tranparent in SL

White:
UnMasked
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.