97. Erase Part of a Layer
Before You Begin
91 About Layers and the Layers Palette
95 Convert a Background Layer to a Regular Layer and Vice Versa
163 Mask an Image Layer
164 Replace a Background with Something Else
One advantage of using layers is the ability to isolate changes to various elements in an image, such as applying a contrast adjustment to just a person and not the entire image. Another advantage of using layers is that you can easily add and remove data from a layer without affecting the other layers in your image. In fact, when you erase data from a layer using one of the eraser tools, the pixels are changed to transparent ones, and the contents of the layers below become visible "through" the area you just deleted.
If you attempt to "erase" data from a layer that has transparency locked (such as the Background layer), the pixels are not made transparent but are instead filled with the current background color.
To erase part of a layer, you use the eraser tools. There are different types of eraser: the regular Eraser, the Background Eraser, and the Magic Eraser. The Eraser works just as you might expect, making transparent the pixels the brush passes over. The Background Eraser works a little differently. As you drag the Background Eraser tool, pixels under the brush that match the pixel in the center of the brush tip crosshair are made transparent. How closely these pixels must match is controlled by the tool's Tolerance level, which is set on the Options bar. With the Magic Eraser tool, you erase matching pixels by clicking a sample pixel. Pixels that match the sample you clicked are erased from the layer. Again, the Tolerance option controls how closely this match must be before pixels are erased (made transparent). This works well if there is a lot of difference between the pixels you want to erase and the portion you want to remain. To remove a background with lots of different colors, it's easier to use the Background Eraser because you can drag and not click each color to remove. You'll learn how to use the Eraser and the Magic Eraser in this task; to learn how to use the Background Eraser, see 164 Replace a Background with Something Else.
Eraser A tool that allows you to erase (change to transparent) the pixels under its brush.
Magic Eraser A tool that allows you to click on a pixel and instantly erase matching pixels. This tool, and a similar tool called the Background Eraser (which works by dragging and then erasing pixels similar to those under its crosshair), enable you to easily erase the background behind your subject (make the background transparent).
Select Eraser Tool
Open an image in the Editor in Standard Edit mode and save it in Photoshop (*.psd) format. On the Toolbox, select the Eraser tool.
You can also erase data by making a selection and pressing the Delete key.
Adjust Eraser Settings
On the Options bar, select the Mode (Brush, Pencil, or Block), which determines the shape of the brush tip. For the Brush and Pencil options, you can further refine the tip by selecting an option from the drop-down list. Set the Size and Opacity. If you lower the Opacity, for example, the eraser only partially erases (it makes the pixels partially transparent instead of fully transparent).
Erase Unwanted Pixels
Drag with the tool; pixels under the tip are erased (made transparent).
Select Magic Eraser
Select the Magic Eraser on the Toolbox (if the Eraser tool is already selected, just click the Magic Eraser icon in the Options bar).
Set other options as well. Enable the Anti-Aliased check box to make sure that the edges are smooth around the area that is erased. Enable the Contiguous check box to erase only pixels that are adjacent to the pixel you click. If you clear the check box, Photoshop Elements will find all pixels in the layer or selection that match the pixel you click. Enable the Use All Layers check box to remove pixels on the current layer, based on the visible color and brightness of the blended pixel that you click. Again, adjust the Opacity to only partially erase matching pixels.
Adjust Eraser Settings
Set the Tolerance to a value that tells the Editor how closely you want pixels to match the one you click before they are erased. A low Tolerance level indicates that only pixels that are very similar to the pixel you click will be erased. The higher the Tolerance value, the broader the range of pixels that will match.
Erase Unwanted Pixels
Click a pixel that matches the ones you want to erase. Pixels that match closely enough (based on the Tolerance setting) to the one you click are erased. Continue the process until you have removed the unwanted portion of the layer. The portion of the layer you erased no longer blocks any data on the layers below, and that data becomes visible.
View the Result
When you're satisfied with the image, save the PSD file. Then merge the layers together (if any) and resave the result in JPEG or TIFF format, leaving your PSD image unflattened so that you can return at a later time and make different adjustments if you want.
In this example, I pasted an image of my husband's model boat, taken in a backyard pool, into a larger image of a mountain lake. (The boat image was pasted in on a separate layer, making it easy for me to resize the image layer before I did anything else.) I wanted to remove the pool water from around the boat so that it would look like it was sitting on the lake. To accomplish this, I used the Magic Eraser tool to remove the pool water around the edges of the boat. I clicked on areas of the water, and the matching pixels were erased. Because there were several different shades in the water, I had to click several times.
Using the Magic Eraser enabled me to erase water pixels without accidentally erasing the boat. After the pixels near the boat were erased, I could work quickly with a large Eraser to remove the outer remains of the layer, by simply dragging over them indiscriminately. In the resulting image, my husband's model boat sits convincingly on the lake, looking for all the world like a full-sized boat. I have a bit more work to do to make the illusion perfectly convincing, such as lowering the brightness of the boat a bit to match the conditions of the water, and adding a shadow, but I'm nearly there.