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November
2003

Vectoring in on Vectors

Fig. 1
Win
Mac

Vector graphics, raster graphics…it’s enough to make you throw your hands up and go back to the days of the simple 8-bit paint program that limited you to a mere 256 colors and basically used tools to turn pixels on and off. Adobe Photoshop has included vector type and shapes since version 6 and these are also included in Photoshop Elements 2. This month we’re going to look at these useful and versatile features.

First, let’s have a brief recap. Raster graphics are composed of a grid of dots called Pixels. There is a finite number of Dots Per Inch (DPI); if you print your image large enough you will see underlying grid structure of the pixels. You’ll see the stair-stepped edge, the jaggies, the pixelization of the image. Vector graphics, on the other hand, are described in a series of equations and properties. Specifically a vector is “a line or movement defined by its end points, or by the current position and one other point” according to Dictionary.com.

Vector art uses geometry to collage together a series of lines or shapes that overlap and compliment each other. Each object is defined as to its size, starting point, color and other variables. Each vector object is then individually manipulable, unlike the brushstrokes of a painted raster image. These geometry-based images give another major benefit: they are resolution-independent. When vector data is sent to the printer, it is rendered at the full resolution of the printer. This means that there is no jaggies or pixelization, the image is as smooth as the printer can render it. Another benefit is that adding a vector layer increases your file size by a negligible amount, adding additional raster layers can bloat a file to many times its original size.

The specific tools that you use in Photoshop for these vector shapes are the Text tool as well as the Rectangle, Rounded Rectangle, Ellipse, Polygon, Line and Custom Shape tools (these are located ‘under’ the Rectangle tool, click-and-hold on the Rectangle to see the others) (Fig. 1). Adding any of these will create a new Type or Shape Layer in your image.

The vector shape tools have several different modes available in the Options bar (Fig. 2). The icon on the far left allows you to save preset shapes; the next three icons define what the shape tools draw. First is to draw a vector Shape Layer, next draw a Path, and finally a more traditional fill the pixels in the shape without using any vector information. The next set of icons let you toggle between the different vector drawing tools, the same as using the Tools palette, but with tools-specific options to the right.

Fig. 2
Fig. 3
The default drawing mode is one shape per layer, but by making selections in the next set of Option bar icons you can add to a shape layer (putting two or more shapes on the same layer), subtract a new shape from the existing shape layer, show only the parts of the shapes that intersect, or exclude the overlapping areas of the shapes. With any of the shape tools selected you can temporarily go into additive mode by holding down the Shift key. To temporarily go into subtractive mode hold down the Alt key (Windows) or the Option key (Mac OS). These different modes allow you to make some complicated vector graphics from the basic shapes. The full version of Photoshop also lets you use the Pen, Freeform Pen, Path Select and Direct Select tools to create or modify vector shapes like you would a Path. This feature is not available in Elements.

In the Layers palette, you will notice that the Layer icon is simply shows the color, while to the right is a Vector Mask icon showing the shape (Fig. 3). To change the color of the shape, double-click on the layer icon. To these shapes you can apply any of Photoshop’s Layer Styles to create some really cool effects: drop shadows, embosses, glows, gradient or texture overlays, etc. Running Filters on vector layers will result in a dialog box that warns you that the layer will be rasterized (converted to pixels). 

Type layers work the same way in regards to Layer Styles and Filters. These layers can be converted to vector shapes by selecting TypeConvert to Shape from the Layer menu. This lets you keep the vector properties while being able to modify the typography with the other drawing tools.

Fig. 4
To get all this vector information to print at the full resolution of the printer, you have to take a little extra care and you have to be printing to a PostScript printer (PostScript is the printer language developed by Adobe in the 1980s for desktop publishing). This would typically be a PostScript laser printer; most inkjet printers would need an additional PostScript interpreter to have this capability. In Photoshop, select Print with Preview from the File menu. Make sure the Show More Options box is checked and select Include Vector Data (Fig. 4) before you hit the Print button. 

To print the vector graphics in your Photoshop document from another program (i.e. a page layout or illustration program) you have to save the document as either a Photoshop EPS (Encapsulated PostScript) or DCS (Desktop Color Separations, not available in Photoshop Elements) file. After clicking the Save button, be sure to check the Include Vector Data box in the resulting EPS or DCS Options dialog box (Fig. 5), where you will also be warned that if the file is opened up again by Photoshop the vectors will be rasterized. You will want to save an editable copy in Photoshop’s native PSD format. Some Adobe programs like Illustrator 10 and InDesign 2 can open or import PSD files and preserve their vector information. Photoshop’s Enhanced Tiff format also preserves the vector and type layers, but it is not commonly supported yet and offers no real benefit over the PSD format.

Fig. 5
This vector tool inclusion in what is traditionally a pixel-based program is one more reason why Adobe Photoshop is still the industry standard image editor.

Paul Vaughn is a freelance graphic artist, writer and web designer. Everybody was a newbie at some time. If you would like to see the Graphics Guy address a specific topic email Paul Vaughn at paulv@mac.com.

 

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