By Steve Bain
Recent versions of CorelDRAW include powerful new onboard tracing tools you can use to quickly trace your digital images into vector artwork. In this tutorial, I’ll highlight the value of using CorelDRAW’s revamped bitmap-tracing tools and demonstrate the results of using various tracing options.
Although it’s built right into CorelDRAW, the PowerTRACE utility virtually qualifies as a separate program. It enables you to start out with any pixel-based image and end up with a set of fully editable vector shapes. The compact, well-organized interface (as shown below) includes unique tools and features in a self-contained dialog. It includes the best parts of the older CorelTRACE application included with previous versions, but it gives you more control over the most important aspects of tracing.
What Does PowerTRACE Do Exactly?
Photo-tracing has long been a technique used by illustrators as a shortcut for creating vector-based illustrations from pixel-based images. Computer-based tracing applications have historically demanded plenty of resources to accomplish this task, but mainstream computers are now faster and more powerful. The complex calculations and the ample memory required for bitmap-to-vector tracing operations now make these tasks relatively easy to accomplish.
PowerTRACE enables you to automatically trace the color areas in a pixel-based image and translate them into vector shapes that closely mimic the original bitmap (as shown below). Why would you want to do this? Simply put, vectors provide more flexibility, editing options, and often better printing quality.
First, you can do more with vectors than bitmaps. If you have experience with Flash movie formats, you likely already know that vector shapes require significantly less memory than bitmaps to display and print. Vector shapes can also be infinitely resized and are easily compatible with virtually any PostScript or non-PostScript printing technology.
Next, there are certain reproduction technologies that are incompatible with bitmap formats. For example, plotting and cutting devices often used in special-purpose operations have difficulties reproducing bitmap images. This can present difficult quality problems if the bitmap happens to be a company logo or product branding. Tracing enables you to quickly and accurately create a vector version that is completely compatible with any reproduction technology.
Graphic appeal is another advantage you’ll enjoy by converting bitmaps into vectors. During your tracing operation, you can simplify the color, shape, and detail of the resulting vectors to create a unique graphic interpretation of the bitmap you have used as a source. With all these great reasons to go vector, suffice it to say that vectors beat bitmaps hands down in any side-by-side comparison.
A Quick Tour of the PowerTRACE Features
If you’re new to tracing, you’ll be surprised at just how easy it is to create your traced vectors. Using the fastest technique, you can just click on a bitmap, choose Quick TRACE from the Trace Bitmap Property Bar selector and you’re done. Your bitmap image is traced automatically at default settings and the vectors are simply placed as a group of objects in front of your bitmap.
For more control over the tracing operation you can use the next fastest technique: Choose a specific image type (as shown below) to open the PowerTRACE dialog, wait a second or two for the previewed results, and click OK. The trace settings are pre-selected and the preview is automatic.
Or course, tracing can be much more comprehensive than just a few simple clicks if you need it to be. While the PowerTRACE dialog is open, you’ll notice it includes a preview area on the left, preview tools and options across the top (as shown below), and tabs for Options and Color on the right. The bottom of the dialog also includes a progress bar, buttons for Undo, Redo, and Reset, and an invaluable resizing tab so you can view more or less of the tracing dialog if you wish.
You’ll find the standard tools (shown below) for zooming, fitting, or panning the preview window are invaluable for evaluating your trace preview.
The preview selector also enables you to view your trace results one of three ways. Choose from a standard Before & After split pane view, a full Large Preview pane view, or a full-pane view with a Wireframe Overlay. The latter view mode enables you to see the resulting vector shapes as red outlines superimposed over your original bitmap in varying degrees of transparency.
The new resources available in the Options and Color tabs provide total power over your trace results. The Options tab features new trace controls, new color mode and background options, and displays the current trace result details. The Color tab includes completely new color palette options and commands for merging and editing the traced color areas in your bitmap (more on these later).
Get into the Tracing Action
You’ll want to check out the new Image Types available in the dialog selector. You can use these to simplify or intensify your tracing operation with pre-set values based on the properties of your digital image and the intended purpose of the resulting trace. Your results will vary depending on the type you select and the inherent detail and colors in your bitmap. As you experiment with different trace types, keep one eye on the Trace Result Details area (shown below) to see the number of curves, nodes, and colors that result from using certain settings.
In the example below, a digital photo was traced using each of the six image types. As you can see, choosing Line Art, Clipart, and High Quality Image produces more accurate and complex trace results than the Logo (the Quick TRACE default), Detailed Logo, and Low Quality Image.
Manipulating the Smoothing and Detail sliders offers you custom control over the quality of your trace results. Adjusting the Smoothing slider enables you to control the complexity of the traced areas and directly affects the number of nodes per object. The example shown in the illustration below demonstrates the affect of smoothing on traced vectors.
The Detail slider position determines the size and color threshold of the traced areas in your bitmap. Higher tracing detail lowers the detail threshold causing smaller areas of color to be traced. This usually results in a greater number of objects and colors in the final traced result. The illustration below shows example variations on the effects of different detail settings.
Exploring Background Options
PowerTRACE enables you to specify how background colors are handled. Background options enable you to eliminate the background portion of your image automatically. While the Remove Background option is selected, you can use the automatic or manual options to apply a soft mask during your tracing operation. With Automatically Choose Color selected, PowerTRACE automatically detects the background color-typically using the color at the upper-left or bottom-right image corner.
You can also use the Specify Color option and choose your own color from the color selector, or choose the eyedropper tool and click directly on the trace preview to interactively specify the background (as shown below).Choose Remove color from entire image to eliminate this color globally throughout your image. Here’s a trick: Hold Shift and click the trace preview with the eyedropper tool to specify and eliminate multiple colors.
PowerTRACE can also handle imported bitmaps that have selection masks applied to them, giving you the freedom to eliminate backgrounds even before your bitmap reaches CorelDRAW . This means you can apply a mask using selection tools in PHOTO-PAINT or use the new Cutout Lab to eliminate your bitmap’s background before you import it. When the image is selected for tracing, the mask is automatically preserved and the masked colors ignored (as shown below).
Tracing Color Gone Wild
The Color tab provides a completely new set of color palette resources and tools for you to manipulate and apply to your trace results. The top portion of the Color tab displays the color samples of the actual colors that were traced from your bitmap. Hold your cursor over a sample to view the specific color values popup-style. If the palette includes 16 samples or less, the color values are displayed directly on the samples (as shown below).
Below the color sample list, you’ll notice a set of buttons (see below) that enable you to control and manipulate the current sample results. Click the Open Palette button to open any of the saved CorelDRAW color palettes to apply to your image. The palette you open is automatically mapped to the existing color values in your trace results.
Applying uniform color palettes across multiple images enables you to quickly adapt a traced image to a set color scheme or design. You can choose from saved RGB, CMYK, or grayscale color palettes. Click the Save Palette button to save your current sample results as a unique palette (PAL) file to apply to other traced images. In the example below, several variations of saved RGB palettes were applied to a flower image.
Beside the palette buttons, you’ll find the Merge and Edit buttons. The Merge button enables you to combine two or more selected samples into a single color sample, in effect reducing the total colors in your trace. Click directly on a sample to select it, and/or hold Shift and Ctrl as modifier keys to select continuous or contiguous samples (respectively). The merge results in an averaged color value of your selection.
You can use the Edit button to open the Select Color dialog and alter the specific color model of a sample selected in the list. This way, you can customize the each palette sample to suit a specific purpose. Here’s another tip: Select multiple samples and click the Edit button to edit and merge a selection of colors in one step.
You can also use the Number of Colors and Color Mode options found in both the Options and the Colors panes to control the total number of color samples in your trace results. Each time the color mode or palette range is altered, the sample list is remapped using color averaging.
Best Tracing Practices to Consider
As anyone with tracing experience will tell you, there are always pros and cons involved in using automated tools and PowerTRACE is no exception. But like most things in life, there are always workarounds you can use and tricks you can adopt.
One of these challenges involves graduated color. Images that include sky, fading lights, and blurred images almost always involve graduated color. But, the color fills applied to the shapes that result from tracing a bitmap image are solid, uniform colors. Tracing inevitably produces a complex series of shapes which look nothing like the graduated color area in your image. Increasing the tracing detail will lessen the effect, but doing so will also increase the complexity of your trace results.
One solution to this is to remove the color shapes comprising the graduated area and replace them with a single fountain-filled shape. Blue skies are a prime candidate for this since the sky often fades uniformly from one color to another. In the example shown below, a complex series of similarly colored shapes was replaced with a fountain-filled rectangle, essentially eliminating more than 150 objects and colors from the final result.
Another challenge you might face in your tracing adventures is the varying detail required to render the visual elements in a single image.
For example, you may want more detail in the subject matter of your image than in the background. In this case you might consider a two-step tracing process. Trace the entire image once using a low detail image type such as Logo or Low Quality Image and use this to represent the background. Then, trace the subject matter portion with more detail and combine the two traces into a single arrangement.
In the example shown below, a low-detail trace, color merging, and color reduction was used to simplify the background from more than a hundred objects to a few dozen. The subject detail was preserved by tracing at a higher level of detail while the background colors were removed using the eyedropper tool.
The sky is the limit when it comes to image types, so experience will ultimately be you’re best teacher as you experiment with the new tools and options built into PowerTRACE. Whether you’re tracing logos, churning out clipart, or creating elegant designs, this is certainly a welcome enhancement to CorelDRAW.
Steve Bain is an award-winning illustrator and designer, and an author of nearly a dozen books, including CorelDRAW®: The Official Guide.