Exercise #3: Making more complex selections

So, we've used "SHIFT" to constrain proportions with the Marquee Tools. SHIFT can also be used to Add to Selections. That is, to select more than what you've already got selected. Let's open a new file, same as before: 20x20 with a transparent background layer. Now, zoom in & select a portion of that window with any method you've learned so far. Now, hold SHIFT down, click and drag the Marquee to add new selections to the existing selection. Outside of it, preferably. For example, here’s a selection, and then the same selection with more areas selected:

I used both Marquee tools. Do that as much as you like.

What about using SHIFT for making perfect squares and circles? In order to Constrain Proportions while adding to a selection, since you need SHIFT to do both, here's what you do. Make a selection. Hold SHIFT and start adding a new selection to it. While holding the mouse button down (or keep holding the pen to the drawing tablet), you can actually let go of SHIFT at any time after you begin adding to your selection. SHIFT is only necessary to initiate adding to a selection. If you press and hold it again, you will now be constraining the proportions. Let go of it again and you'll be back to the normal mode. Just don't let go of that mouse button or you'll have to start over.

You can also Subtract from selections. Basically it's the same thing, except instead of holding SHIFT, you hold OPTION on Mac, and ALT on PC. So, using the existing selection you just made, (or deselect & make a new selection), hold OPTION (or ALT on PC) and drag a new selection over a portion of the existing selection. Viola! It's been subtracted from. Here's what mine looks like now, along with the selection filled in to show you what it looks like.

Inverse Selections: And finally (for now) you can Invert existing selections. To invert a selection is to select the opposite space that is currently selected. Use your existing selection if it's still active, or you can make a new one to try this out. To do this on Mac, press "SHIFT" + "COMMAND" + "I", and on PC press "SHIFT" + "CTRL" + "I". Or you can choose "Select" > "Inverse". I will fill my image in to show you the results.

Conclusion