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When we're ready to superimpose Massimo in his swan boat against the sea of his drawing, we will need a special type of image, one with a custom-made alpha channel. In Photoshop, pull down the Window menu and choose Channels. If you have an image open that is in RGB mode, you'll see it's made up of four channels: red, green, blue (which together stand for RGB) and a composite channel (which shows how the colors combine). An alpha channel is another, invisible gray-scale channel. By default, it is plain black, but we can cut out (or mask) an interesting shape and isolate it from the rest of the image. For our purposes, we want to isolate the interesting shape of a boy sitting in a swan from the rest of the image, a merry-go-round on a cobblestone street.

 

 

To draw around Massimo, we'll choose the lasso tool.

Holding down the Option key and the mouse button, draw around Massimo. As long as you hold down the Option key, you can let up on the mouse button whenever you want, and the drawing will stop and wait for you to hold down the mouse button and continue. This allows you to trace around the image a little at a time. Without the Option key, you'd have to trace it all in one stroke, which is not easy for most of us. When you have traced all around your shape, let up on the Option key and the mouse button. Your outline stands at the ready. Go down to the Channels window and click on the Quick Mask button.
Your selected outline instantly becomes a new channel.

Save your file in your Sized Images folder. We'll come back to it later when we discuss Alpha Channel transparencies in Premiere.