on the 2nd week, Madam Ling told us about how to convert photo from raster to vector with adobe illustrator
Begin Tracing
The first step in the tracing process is to get something to trace. Because tracing is the process of converting raster data to vector data, you need a raster image open in Illustrator. For instance, this could mean that the raster artwork is a small part on a larger artboard, or you open a .PSD file using the File > Open command to trace it.
- Open an Illustrator document that already contains raster content, place a raster image into an Illustrator artboard using the File > Place command, or paste raster content you select from a program such as Adobe Photoshop.
- Choose Window > Image Trace to open the Image Trace panel. In previous versions of Illustrator, you had to apply the Live Trace command in order to see the tracing options in a separate dialog box.
- With the Selection tool, select the raster image on the artboard. After selecting raster content, the Image Trace panel will spring to life, and the options will no longer be dimmed
4. Notice in the Control panel the Image Trace button with an arrow to the right. By clicking the Image Trace button, you apply the default tracing option to the selected raster content. By clicking the arrow to the right of the button, you can choose a tracing preset with which trace the selected content. You can also choose Object > Image Trace > Make to trace selected raster with the default tracing options or choose Object > Image Trace > Make and Expand to trace and expand the content immediately (I discuss expanding shortly). At the top of the Image Trace panel, click the High Color button to trace the image using the default High Color settings. Depending on the speed of your machine and the image content selected, the time required to trace may vary
At the top of the Illustrator Image Trace panel is a series of preset buttons that offer generic tracing options which most of us will use at some point or another, depending on the project. There is also a series of preset options in the Preset menu below the buttons. The buttons at the top of the panel (mostly) coincide with an option in the Preset menu. For instance, the High Color button is similar to the High Fidelity Photo option in the Preset menu, and the Low Color button is similar to the 16 Colors option in the Preset menu. The Preset menu offers more options.
When you trace an image using one of the tracing buttons or a trace preset, the raster image data is converted to an Image Tracing object. This means that you can adjust the tracing options, even trying different presets, but it is not editable vector. As a matter of fact, you will see Image Tracing on the left end of the Control panel with the newly traced content selected
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After choosing a starting preset to trace the image, you can then either accept the tracing results or adjust the tracing options to better suit your tracing needs.
Editing the Tracing Options
After choosing a starting preset to trace the image, you can then either accept the tracing results or adjust the tracing options to better suit your tracing needs.
- In the Image Trace panel, choose Tracing Result with Outlines from the View menu.
Showing the outlines can be helpful for seeing how many vector shapes will be created when you trace.
2. Choose Tracing Result from the View menu.
3. Press and hold the Eye icon to the right of the View menu in the Image Trace panel to view the original image on the artboard. Release the mouse button to return to the tracing results
4. Drag the Color slider to the left to decrease the number of colors in the Image Tracing object
If you look at the bottom of the Image Trace panel, you see a listing of the total number of paths, points, and colors. Notice that the number of colors listed there doesn’t match the number of colors listed in the Colors value (the slider). The Colors value refers to the color accuracy in percent of color. Less accurate means fewer colors (typically) and not depicting the color of the image as accurately.
5. From the Palette menu in the Image Trace panel, choose Limited. Change the Colors value to 4 by dragging the slider (see Figure 9). After viewing the result, change the number colors to 16 or so.
The Limited option limits the number of colors in the Image Tracing object to 30 by default. You can adjust the Colors value (the slider) or type a number into the field to the right directly to edit the number of colors. This value allows you to choose the actual number of colors in the object, rather than a percentage.
TIP
For every change that you make in the Image Trace panel, Illustrator needs to apply the new options to the Tracing Image object on the artboard. If you want to set a series of options at once, without waiting for the update, you can deselect Preview at the bottom of the panel and then select it again when you are finished setting options. Also, if you drag the Colors slider, for instance, and want a specific value, the Image Tracing object won’t update (with Preview selected) until you release the mouse button on the slider.
Advanced Tracing Options
If you find that the tracing results still aren’t what you want or expect, you do have the option to edit the advanced settings in the Image Trace panel. Unlike CS5 and earlier, treading into the advanced tracing option territory isn’t quite as mysterious.Click the Advanced arrow in the Image Trace panel to toggle open the Advanced options.
The top three options are where you can fine-tune the tracing. Here’s what each of these options mean:
- Paths: Dragging the Paths slider to the right makes the paths fit tighter to the original “shape” (more anchor points), whereas dragging to the left makes the paths fit looser (less anchor points).
- Corners: Dragging the slider to the right makes more corner points, and dragging the slider to the less makes more smooth points.
- Noise: Suppose that the background of an image you were tracing contained some unwanted content such as artifacting or dust/spots. By increasing the Noise value (dragging the slider to the right), you can exclude some of that content from the tracing result. The pixel value of Noise refers to the smallest pixel area (not just width or height) that will be traced, and not ignored
And yes, even understanding what each of these is intended to do, some of us (me) will sometimes just drag the sliders back and forth to see what happens.
The Method option has two options: Abutting and Overlapping(see Figure 12). These options can be very important, depending on the result you are looking for. This is a new option in CS6 and works sort of like print trapping turned on or off. Here’s what I mean:
- Abutting: The vector shapes that are created when an image is traced butt up against each other with no gaps between (typically).
- Overlapping: The vector shapes that are created overlap each other just a bit. This can sometimes result in small “gaps” between the vector shapes.
1. With the Image Tracing object still selected, choose Black And White from the Mode menu. The Create option will become available when you choose Black And White from the Mode menu.
2. Deselect Fills in the Create options area, and Strokes will become selected (at least one needs to be selected). For black and white tracing, you can choose to create shapes with strokes, fills, or both.
- Selecting just Fills creates filled shapes when the image is traced. Selecting just Strokes will create stroked paths from content that falls with the range in the Stroke option beneath the Create options. Selecting Fills and Strokes together will create stroked paths for content up to the size of the Stroke value and filled paths for everything over that size.
Lastly, the Ignore White selection towards the bottom of the Image Trace panel can save you some time. Any pixel data that is white in the resulting vector data will not be included. In other words, for the apple image you’ve seen in this article, the white background will not be a shape and will be transparent. That also means that the highlight on the apple that is pure white will wind up being a hole, or area with no shape.
After you finish tracing, you can either choose to leave the vector content as an Image Tracing object, which means you can’t directly edit the vector shapes, or you can expand the tracing results and turn the Image Tracing object into a group of vector objects (shapes and/or paths—depending on the options set). You can click the Expand button in the Control panel or choose Object > Image Trace > Expand to expand to shapes.
Here are a few things to consider:
- If you place an image and link to it (when placing), trace it, then expand it, the raster image that is traced is no longer linked to the original and cannot be updated directly.
- Expanding an Image Tracing object commits you to the tracing settings. In other words, you can’t edit the option in the Image Trace panel for that content after expanding.
- An Image Tracing object that has been expanded will, more often than not, be smaller in file size than the non-expanded Image Tracing object.
- You can “clean up” an image in a program such as Photoshop before tracing. Sometimes I will increase the contrast in an image to be traced, almost to the point of not looking right (too much contrast). In some cases, this can make it easier for Illustrator to determine what is what (where edges are, etc.). Also, you can use the touch-up tools in Photoshop to remove unwanted content before tracing.
- In CS5, when tracing a web-optimized image, such as a JPEG that is 72ppi, it traced the “stairstepped” edge. In CS6, that’s usually not the case.
- Tracing an image that is a higher resolution will usually result in a more detailed trace
- After expanding the Image Tracing object, you can clean up the resulting vector content a bit by choosing Object > Path > Simplify, or attacking the resulting paths and shapes with the drawing tools.
- You can save your tracing options in the Image Trace panel by clicking the Manage Presets button to the right of the Preset menu and choosing Save As New Preset. Saved presets appear in the Preset menu
Final Thoughts
Hopefully I helped clear up a bit of mystery around the tracing options in Illustrator CS6. Tracing in software may never be perfect, and require us to make corrections after the fact, but CS6 tracing has been greatly improved. With a little image clean-up and some patience, you can usually get the tracing results you need or at least get you close. If not, there’s always the option of brushing off the Pen tool and starting over.
To learn more about working with the Image Trace in Illustrator CS6, visit the Illustrator Help website and search for “Image Trace.” Unfortunately, when writing this article, I searched on that topic in Illustrator Help and found that the Adobe Help still referenced the Live Trace functionality from CS5 and earlier.
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