Then, I did an Image Size with Constrain Aspect Ratio turned off to make the image a 150x150 square. Shrinking the image down to the proper size is our next step. Just do an Image Size, set to 32x32. Another quick Unsharp Mask cleans things up nicely. When combined, the RGB channels create a color image.
Alpha channels are a special channel that describe transparency.
They do not affect the colors of the image. I use a zero pixel threshold with AA turned on. Then, invert the selection. Now, go back to the Channel tab, and you should see the shield-shaped selection on the black background. The reason we want to have antialiased edges is to allow the edges of the image to fade gently into full transparency.