Making lace from a photograph or scanned trim is simple and quick when you know how. There's no selection of any kind involved! Just copy the image, paste it into a new Alpha channel, then adjust the Levels.
Watch the movie to find out how to do it! (If you have trouble watching it on line, you can download the .flv file, or download the Quicktime movie.) This movie is old, from a time when I had no mic, and will be replaced with a new, updated one soon.)
The steps involved, once again are
1. Make the Background into a Layer, if it's not one already. (Hold Option, and double click on it.)
2. Select the entire image, and Copy it. (Command A on a Mac, or ctrl A on a PC, to Select All.)
3. Open the Channels Panel, and Create a New Channel using the tab on the bottom. This will be the Alpha.
4. Paste the image into that channel.
5. Open the Levels dialog (Command L on a Mac, ctrl L on a PC) and slide the Input Levels pointers towards the middle of the histogram, watching the K percentages in the Info panel, to make sure that the black is 100% black, so it will be transparent, and the white is 0% black, so it will be opaque.
6. With the Levels dialog still open, adjust the Gray point, to get the balance of Transparent and Opaque that you would like to have. (Moving it towards the left will give you more opacity. Moving it towards the right will make the lace more transparent.)
7. Return to the Layers panel, and make a Mask on the layer to check your transparency. Do this by going to Select > Load Selection, choosing the new Alpha you just made, and then clicking the New Mask button at the bottom of the panel. Your lace will have the transparency you have in the Alpha Channel.
8. Make a new layer, below the lace (hold down the Command key on the Mac, or the ctrl key on the PC, as you click the New Layer button, to make a layer below the currently selected one.)
9. Fill that layer with various colors, to check the Transparency. If it's not what you wanted, option click on the Mask, and play with the levels until it is.
10. Put a color that matches the lace on that bottom layer (or make a copy of the lace, and run the Flaming Pear solidify filter on it to eliminate any colored halo in world. See the tutorial about Eliminating the White Halo for more information on that.)
11. Save as 32 bit .tga, and upload! You're ready to use it in SL™.