What You Can Do with the Pencil Tool in Photoshop CS6
The Pencil and Brush tools in Photoshop CS6 are very much alike, except that the Pencil tool has hard edges by default and the Brush tool can have soft, feathered edges. The Pencil tool can also erase what it creates!
You can do all the following with the Pencil tool:
Drag the mouse to draw freehand lines.
Click at one point, release the mouse button, and then Shift-click at a second point to draw a straight line between the points. As long as you hold down the Shift key, you can keep clicking to draw straight lines between each of the points.
Press the Alt key (the Option key on the Mac) and click any area of your drawing to switch the foreground color to that hue.
When using the Pencil, as well as the Brush, Color Replacement, and Mixer Brush tools, press and hold down the V key to access the Move tool temporarily. Release the V key to return to the original tool. This handy shortcut enables you while drawing or painting to move a layer or selection without having to go back and forth to the Tools panel.
The Pencil tool also offers the Auto Erase option, which you activate from the Options bar at the top. Auto Erase is a handy feature that lets you remove portions of your pencil strokes without switching to the Eraser tool.
When you have Auto Erase turned on, the operation of the Pencil tool is slightly different from the default. The effect of either of the following actions is that Photoshop erases lines you’ve drawn:
When you click an area of the drawing other than an area that’s foreground colored (for example, the pencil lines you’ve already drawn), the Pencil tool begins drawing a line in the foreground color (this is the default mode).
When you click an area of the drawing that’s foreground colored (such as the pencil lines you’ve drawn), the Pencil tool draws by using the background color.
Because the Pencil tool doesn’t use soft-edged lines to draw, anything other than straight vertical or horizontal lines has rough, jagged edges (often called jaggies). Jaggies aren’t objectionable in some cases, especially in higher-resolution images, but if you zoom in on an area containing pencil lines, the jaggies are readily apparent.