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Selection Basics
When you wish to edit part of an image file in Photoshop, you must first select the region that you wish to change. When you select a part of an image the selected area will be indicated by a dashed selection border called a “selection marquee.” The changes that you then make will only affect the area inside of the selection, protecting the rest of the image file against changes. In this chapter, you will learn about selecting in Photoshop and what tools we have available for us to use.
There are two types of selection that you can make in Photoshop. You can either make pixel-based selections for editing bitmap images or you can select a vector-based image path (which contains no pixel information). For example, when you create a shape using the “Pen Tool,” it creates a path. You can select paths or pixel-selections. You can also convert pixel-based selections into paths and vice versa. In this chapter we will also look at using the “Extract” command to select an element in a picture and then erase the background to transparency, isolating the selected element.
Making Pixel Selections
There are several ways that you can make pixel-based selections in an image file. Photoshop provides you with several tools that you can use to select pixels in an image. You have a set of marquee selection tools, a set of lasso tools, and the magic wand tool, among others. There are also a few commands that we can select from the Menu Bar that will also allow you to make pixel-based selections.
After you make an initial selection, making another selection will typically replace the previous selection. However, we do have some additional selection options that allow us to add secondary selections to a primary selection, subtract a secondary selection from a primary selection, find the intersection of multiple selections, or find the union of multiple selections. Once you make a selection, you can move the selected area by simply clicking into the middle of the selection and dragging the selected area to a new location before releasing it.
To make selections using the Menu Bar, you can use the “Select” menu command. Before you make a selection, you must ensure that you have the appropriate layer of the image selected in the Layers Panel. Click on the layer in this panel from which you would like to make a selection, first. Then you can freely select using the Menu Bar or one of the tools available in the Toolbox.
If you wish to select all of the pixels in an image, you can select “Select| All” from the Menu Bar. To deselect a selection, select “Select| Deselect” from the Menu Bar. If you are using one of the marquee tools or the lasso tool, you can also simply click one time into the image outside of the selected area to deselect a selection, as well. You can select your previous selection that was made by selecting “Select| Reselect” from the Menu Bar. If you make a selection in an image and then wish to select everything except what you had initially selected, you can select “Select| Inverse” to select everything that wasn’t selected, excluding the original selection that you made.
The Marquee Tools
The Marquee Tools in the Toolbox allow you to select basic shapes. You can create a selection that is a rectangle, oval, or a horizontal or vertical 1-pixel line. To make a selection using one of these tools, you can first select the type of tool that you want to use from the Toolbox. Then you just click and drag from one corner of the selection area to the other, releasing the mouse button when you are finished.
So let’s take a look at all of the options that we have when we make a selection using the marquee tools in the Toolbox. First, start by making sure that you have the correct image layer from which you want to make the selection selected in the Layers Panel. Then select the desired marquee tool that you want to use from the Toolbox. They are all located on the button in the upper left corner of the Toolbox. You can right-click the button to view the list of button options and then left-click on the choice you want.
Next, use the Options Bar to specify which selection setting you wish to use: “New Selection,” “Add to a Selection,” “Subtract from a Selection,” or “Select an Area Intersected by Other Selections.” After you have clicked the desired button in the Options Bar, you can then select a “feathering” option for the selection by typing (in pixels) the width of the border that should be feathered. Feathering softens the selection border so that it isn’t clean and crisp. If you are using the Elliptical Marquee Tool, you can also check or uncheck the “Anti-alias” checkbox. With anti-aliasing enabled, the edges of the rounded selection appear less jagged then when anti-aliasing is disabled.
Next, select a “Style:” for the selection. This will only be an option for the Rectangular Marquee Tool and the Elliptical Marquee Tool. If you select “Normal,” then you will create the selection marquee by simply clicking and dragging. If you select “Fixed Ratio,” then enter a desired height-to-width ratio in the “Height” and “Width” text boxes. When you click and drag to draw the selection, the height-to-width ratio entered here will remain intact as you select. If you select “Fixed Size,” then enter the specific size in pixels in the “Height” and “Width” text boxes. You will not have to click and drag to make your selection, but rather you will click once to create a selection of the size that you specified.
Now to create the selection, just click and drag over the area that you want to select. If you hold down the “Shift” key as you drag the marquee selection, it will draw a perfect square if using the Rectangular Marquee Tool or a perfect circle if using the Elliptical Marquee Tool. If you are using the single line marquee, just click once to create a single line either horizontally or vertically.
If you wish to reposition the selection after you have drawn it, just click and drag from the center of the selection area and drag it to a new location, releasing it when it is in the correct place.
