Photoshop Masking Advanced ( Part 4 )

Photoshop also offers more permanent masking tools such as the Background Eraser. Like the Eraser tool and the Magic Eraser tool, the Background Eraser deletes the unwanted information instead of merely hiding it with a mask. It’s a necessary trade off though, as the background eraser is incorporating “color decontamination” into the selection that it makes. So, not only is it choosing colors and erasing like the Magic Eraser, it is also looking at the colors in the edge pixels and removing any unwanted cast from them to avoid the halo that is common to composited images. Unfortunately this cannot be done in a channel so the changes are permanent. The background Eraser uses a brush that has a sample point in the center and an affected area that is the size of the brush.

One of the common tricks used to make sure that not too much information is deleted is to create a duplicate of the layer before using the Background Eraser. Another good trick is to make a snapshot of the image so that you can paint back in areas that might have been deleted with the history bush.

There are several options for the background Eraser that make the tool more precise and will help you to get what you want erased. The Limits feature can be changed to select and delete contiguous or discontiguous pixels or stop when it finds an edge. In this example, near the hard edge areas like the pants as well as the sweater area, I’ll use the Find Edges option. This will restrict the brush from jumping into her sweater and deleting the fabric that is the same color as the background. In the softer area of the hair, I’ll use the discontiguous option so that the brush will delete the background that is seen through the hair.

The sampling options determine how often or what color the Background eraser deletes. Choosing from sampling once, sampling continuously or using the background color controls the erased color as you move the brush’s sample spot over the image. In this example, since the background is similar, the Sample Once option was used. If the background varied in tone, then the Sample Continuously option might have worked better. Finally the Tolerance option works the same as in other tools, the higher the setting, the more dissimilar the pixels can be. Throughout an image it is not uncommon to have to change these settings. Finally, adjustments such as color balance and filters such as Gaussian Blur can be used to make the images appear to fit together better.