|Adobe Photoshop Basics|
In Photoshop 5.0, there was only one eraser tool, but in Photoshop 5.5, two new eraser tools were added: the background eraser and the magic eraser. (Continued below...)
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The Eraser Tool
The eraser tool shortcut is E. The standard eraser tool has four painting modes to choose from: paintbrush, airbrush, pencil, and block. These modes work just like their painting tool counterparts, except for the block tool, which as you can probably guess, is a simple square block. The difference is, instead of painting the foreground color onto your document, the eraser tool paints in transparency... Unless your layer is a background, in which case, the eraser tool paints with the current background color.
The eraser tool options are basically the same as the painting tools, with the addition of one new option: Erase to history. When you erase to history, it works just like the history brush. Instead of painting in transparency or the background color, you are painting from the active history state in the history palette. You can temporarily switch to Erase to History by holding the Alt/Option key down while the erase tool is active.
The Magic Eraser
The Magic Eraser works just like the magic wand, but instead of making a selection, it immediately converts the pixels to transparent. It's also very similar to using the paint bucket in clear mode. The areas to be erased are controlled by adjusting the tolerance and contiguous options. Clicking once erases all the the pixels that fall within the tolerance range. If the magic eraser is used on a background layer, the background is automatically promoted to a layer.
This tool is best for when you have a background that is fairly solid in color. It just takes one click with the magic eraser and your background is gone. In general, though, you'll need to experiment with the tolerance settings until you get better at being able to eyeball the correct tolerance level.
The Background Eraser
The background eraser also erases to transparency, but instead of using only the tolerance range, it continuously samples the background colors in your document as you erase. It's useful for backgrounds that have a range of colors in the background, but where the background colors are still distinct from the foreground object you want to isolate. It works best with a fairly large brush.
To use it you would position the crosshair over the color you want to be erased, and use a series of single clicks to eat away at the background, or slowly drag along the edges of the object you're trying to isolate.
The most important thing to remember with this tool is to be very careful to keep the crosshairs away from the object you want to keep. When using this tool, you may notice some bits of the foreground object becoming slightly transparent along the edges. You needn't be terribly concerned with this, because you can always paint those bits back in using the Erase to History option or the History Brush.
The background eraser is a great tool for quickly isolating an object, but it does have a tendency to leave stray translucent pixels in the background. You'll almost always want to drop a solid white background layer behind the object and do some cleanup after using this tool.
Now that you've been introduced to these tools, it's time to start using them. Over the next several pages, you will work through 10 exercises utilizing each of the painting tools combined with many other features we've learned so far. Feel free to save your work and post your results to the interactive classroom. Before you begin, you'll need to download and unzip this file which contains all the files you will need for these exercises. (Mac users can use Aladdin's free Stuffit Expander to extract the zip file.)