Masking Tools
Photoshop 5.5's addition of powerful masking tools, such as the Magic Eraser, the Background Eraser, and the Extract Image, make masking easier than ever. All of the tools have a few associated parameters that can be set to accommodate the values of different images. Consequently, you will need to learn each tool through a little bit of trial and error, by opening a few different images and experimenting with the different options.

History Brush
The History Brush brings back pixels from a chosen state in the History palette. When used in conjunction with other tools or procedures, it provides flexible and almost limitless options. In this example, you'll see that it can work well with the Magic Tools. Try using the History Brush after running some filters. For interesting results, experiment with a lower opacity and different brush modes.

To use the History Brush:

1. Open your image. 
2. Use any of the Magic Tools to isolate your subject. (See below.) 
3. In the History palette, click to the left of the original state of the image. 
4. Select the History Brush Tool from the Tools palette. 
5. Paint back the edges of the image until you're satisfied with the edges. Changing the opacity will give you softer edges.

Magic Eraser
Use this eraser to quickly delete the background from your image. The tool differs from the standard eraser button. When it deletes the pixels, it leaves a transparent background rather than the chosen background color. You also use the Magic Eraser by clicking rather than dragging. When you click, the tool deletes pixels within a certain range of color. The Magic Eraser comes with options for fine-tuning the deleting process. Unchecking Contiguous in the Magic Eraser dialog box, for example, will delete all the pixels with similar values. If you set a high tolerance value, the Magic Eraser will delete more pixels within that wider range.

To use the Magic Eraser:

1. Open your image. 
2. Select the Magic Eraser tool by clicking and holding down the eraser button on the Tools palette. 
3. Click areas to delete pixels of similar color. Use the palette of Magic Eraser options to fine-tune the tool. 
4. Clean up the edges of the subject with the History Brush or the regular eraser.

Background Eraser
The Background Eraser tool is similar to the Magic Eraser, except that you drag this eraser around, deleting pixels as you go, rather than clicking and deleting large chunks of the image. The most powerful option is found in the sampling drop-down box in the Background Eraser palette. The Once command erases only areas containing the first color you click, making it easy to remove solid color backgrounds. As with the other tools, if you designate a higher tolerance, a greater range of pixels will be deleted.

To use the Background Eraser:

1. Open your image. 
2. Select the Background Eraser tool by clicking and holding down the eraser button on the Tools palette. 
3. Click and drag the eraser around the image. The initial click will register the tool to that color of pixel. As you move around it will delete pixels of similar color according to the values you have chosen in the Background Eraser dialog box, and leave pixels out of that value range untouched. 
4. Clean up the edges of the subject with the History Brush or the regular eraser.

Extract Image
This handy tool is ideal for rescuing a subject surrounded by complex textures, in this case the mulch and shrubbery behind this fine bear carving. Rather than working with a brush from the Tools palette, you're masking inside a dialog box with three menus of options. All you have to do is click and drag a border around your selected image, and then fill in the area you want to extract. Experimenting with the brush size, the sharpness of the border, and the preview mode allows you to work with the border until even the tiniest detail, such as a blade of grass or a strand of hair, can be included or excluded in the final image.

To use Extract Image:

1. Open your image. 
2. Select Extract from the Image menu. 
3. Use the pen to highlight the border of the object you are trying to mask. 
4. Use the bucket tool to fill the area that you want to keep. In the example, we filled the inside of the green outline to protect the bear. 
5. Click preview and tweak the options to get the best results. You can preview your extracted image on backgrounds of different colors by choosing from the drop-down menu next to Show. 
6. Click OK and the chosen image will be isolated. 
7. Clean up the edges of the subject with the History Brush or the regular eraser.