Introduction to Photoshop: More Image Editing
More Image Editing
The image editing techniques described in this section are not advanced, but they build on the techniques presented the the last section. They include techniques for isolating part of an image (selecting), for creating images with multiple layers, and adding text.
In some cases, you may wish to isolate part of an image for editing, or to combine it with other images. In Photoshop, this is called a selection. When part of an image has been selected, the image editing tools and commands work the same way, but only the selected part of the image is affected.
When you make a selection, the part of the image that is protected (that is, not selected) is sometimes referred to as a mask. Just as you might use masking tape to protect part of a wall when you are painting a room, in Photoshop you are masking the part of the image that you want to protect when you have selected part of an image for editing.
When you make a selection, a selection outline appears to show you the selected area. In the following example, a rectangular area has been selected:
Note: In some cases, pixels may be partially selected (see feathering, below). In such a case, the selection outline is only approximate because there is no sharp boundary between selected and masked areas.
To make a selection, click a selection tool icon in the toolbox. Then use the tool as described below.
Note: Take a look at the Options bar for the tool you are using. (If the options are not visible, choose Window>Options.) You may want to adjust the options for the tool (for example, to make the selection feathered).
In some cases, tools may be hidden "behind" other tools. Click and hold the tool to see the hidden tools.
Selecting Rectangles, Ellipses, and Rows: the Marquee tools
The rectangular marquee tool () is probably the most frequently used selection tool. It allows you to select rectangular areas. Click and drag diagonally with it to make a selection.
The elliptical and row marquee tools are less frequently used. They are hidden "behind" the Marquee tool. To select an elliptical area or a single row of pixels, type M to cycle through the marquee tools. Then drag (with Elliptical tool) or click (with Single Row tools) to make a selection.
Selecting Irregularly Shaped Areas: the Lasso Tools
To create freeform selections, you can click and drag with the Lasso tool (). But the lasso tool may not give you enough control. For more control, you may find the polygon lasso and magnetic lasso tools easier to use.
The Polygon Lasso tool () is often quite useful for selecting irregularly shaped areas. To use it, click on the image, then move to another place and click again to create a segment. Click multiple times to create a selection around an irregular area in your image. Double-click to finish the selection. Note: If you are in the middle of selecting and you make a mistake, press the backspace key to go back one segment, or click the Esc key to undo the selection entirely.
Without pressing the mouse button, move the magnetic lasso tool around an area to select it. The tool will look for edges. You can adjust its sensitivity to edges in the options bar.
Selecting by brightness and color: Magic Wand tool (W)
Click somewhere on the image with the magic wand tool to select adjacent portions of the image based on color brightness. The higher the tolerance entered in the Options palette, the more pixels are selected.
Note: In addition to the above tools, there are some additional more advanced techniques for making selections. For example, you can use the Pen tool to create paths. You can convert a path into a selection by choosing Make Selection from the Path palette menu.
General Selection techniques
To hide the selection outline, press Ctrl-H. To display the outline again, press Ctrl-H again.
To invert a selection, choose Select > Inverse. Everything that was selected becomes masked, and everything that was masked now becomes the selection.
To deselect, click outside of the selection, or choose Select > None.
You can also save a selection (Select > Save Selection) for later use (Select > Load Selection).
Adding to and subtracting from current selections
To add to an existing selection, press Shift
To subtract from an existing selection, press Alt
To add to an existing selection based on color, choose Select > Similar.
Moving and Cloning Selections
To move a selection outline, put the selection cursor inside the selected area and drag.
To move the contents of a selection, choose the move tool and drag the selection.
To clone a selection, press Alt while using the move tool.
Saving Selections for Later Use
To save a selection for later use, choose Select > Save Selection. The active selection will be saved, and you will be prompted to give it a name.
To load a saved selection, choose Select >Load Selection.
Feathering gives a selection a softer edge. You can feather a selection by entering a value in the Feather checkbox in the options bar. Or you can feather an existing selection by choosing Select > Feather.
Working with Layers
Images in Adobe Photoshop are made up of layers. Initially, each image has only one layer (called the background layer), but you can add more layers to the image.
Layers are very useful for editing images and creating special effects. For example, you could make a copy of a layer and make some changes to it. If you don't like the results, you can delete the layer and still have your original layer as a backup. You can also combine images by putting different content on different layers.
Note: Keep in mind that layers (except for adjustment layers, described below) require a substantial amount of memory. Photoshop files with large numbers of layers typically are large files.
To work with layers, display the Layers palette by choosing Layers from the Window menu. The following is an example of the layers palette along with an image.
The first column of the layers palette shows which layers are currently visible, indicate by the eye icon. In the above example all the layers are visible. You can change a layer's visibility by clicking in the first column for the layer.
Note: Even when a layer is visible, part of it may be transparent. For example, this happens if you select part of an area and then press the delete key. When part of a layer is transparent, the layers underneath it can show through.
Photoshop represents transparent areas by a checkerboard pattern:
You can change the opacity of a layer by entering a value between 0 and 100 in the Opacity field at the top of the layers palette. For example, at an opacity of 10%, the layer would be nearly transparent; at an opacity of 90%, it would be almost completely opaque. The opacity default is 100%.
Editing you do within Photoshop affects the current layer. In the example above, "Layer 1" is the current layer.
- To make a layer the current layer, click on the layer in the Layers palette.
- To change the name of the layer, double-click on the layer's name, then type in a new name.
To lock (prevent changes to) a layer, click one of the Lock: boxes near the top of the layers palette. From left to right, they are: lock transparent areas, lock pixels (prevent changes to non-transparent areas), lock layer position, and lock all.
Other actions can be performed by clicking on icons at the bottom of the layers palette:
- To link two or more layers, first select them by shift-clicking on them in the layers palette. Then click the link layers icon. When they are linked they move together, so if you reposition a layer you will simpultaneously reposition all layers linked to it.
- To add effects to a layer (for example, shadows), click on the layer styles icon.
- To add an adjustment layer, click the Adjustment layer icon (adjustment layers are discussed below).
- To create a new layer, click the new layer icon at the bottom of the Layers palette, or duplicate a layer by dragging the layer to the new layer icon.
To delete a layer, click the trash icon, or drag the layer to the trash icon (next to the new layer icon).
Adjustment layers are special layers that you can use along with several image editing commands, including Levels, Photo Filters, Hue/Saturation and others. Adjustment layers allow you to make non-destructive (editable) corrections to your images. For example, if you create a Levels adjustment layer, you can go back to the Levels dialog box later and change settings at any time.
To create an adjustment layer, click on the adjustment layer button at the bottom of the Layers palette, then choose one of the menu items (Levels, Curves, Color Balance, etc.). Alternatively, you can choose Layer > New Adjustment Layer, and you will see the same menu of items.
When you choose e menu item, an adjustment layer will be created, and a dialog box appears that allows you to change the settings.
The advantage of this over an ordinary Levels command is that the adjustment layer is fully editable. At any time, you can click the adjustment layer thumbnail in the layers palette to edit the layer. When you do, the dialog box will reappear and you can change the settings.
Unlike ordinary layers, adjustment layers require minimal memory and do not significantly increase the size of the file.
To add type to images use the Type tool ("T" in the Toolbox).
To enter a single line of text, click on the image with the type tool. Then type. A type layer is automatically created.
To create a paragraph (column) of text, click and drag with the type tool, then start typing. When you enter the text, it will wrap at the point where you stopped dragging.
To reposition the text while you are using the Type tool, press the Ctrl key.The Type will change into the move tool so you can move the text box.
When you are finished typing, click the check mark in the options bar. To cancel, click the X mark in the options bar.
To adjust the color and format of your type, select the type and then change the settings in the options bar (at the top of the Photoshop desktop), or use the Character or Paragraph palettes (to display these palettes, click on the text palettes button ( ), which appears in the Options bar whenever the Type tool is selected).
When you use the Type tool, a type layer is automatically created. As long as your type is on a Type layer it is editable. If you convert it to an image layer by rasterizing it (Layer>Rasterize), you will no longer be able to edit it.