Adobe Illustrator’s Image Trace Panel is a powerful tool, used by designers to convert raster images into vectors. But it can be employed in a variety of other ways, as well:
- Tracing photographs – that you have the proper licensing for, of course
- Vectorizing sketches
- Capturing scans (such as textures) onto a computer
It’s a quick and useful tool, and Adobe has added some very interesting updates with CS6. Here is a breakdown of the functionality of the different features of the Image Trace Panel, and examples of the settings at work.
These are the basic set of tools that you can use to control the output of your trace.
At the top of the Image Trace Panel you will see a series of icons. These icons correspond to the Preset settings that are popular for tracing a pixel-based image. From left to right they are as follows:
- Auto Color: Traces the image using a smaller specified number of colors that can be adjusted. Creates a more flat image with fewer colors.
- High Color: Traces the image using a very high number of colors and detail, creating a photorealistic vector image.
- Low Color: Traces the image using a high number of colors, creating an image that is more detailed, but not photorealistic.
- Grayscale: Traces the image using black, white, and an adjustable number of grays.
- Black and White: Traces the image using only black and white.
- Outline: Traces the image using outlines, rather than fills. This setting is a little tricky, and results can be varied with photographs. It’s best used for simple images, hand drawn type, etc. (Not shown below)
These aren’t the only settings, though. The Preset pulldown menu (below the icons) contains more options for popular automated tracing settings:
“View” allows you to toggle between a few different options for how you see the results of your image trace. This lets you monitor the accuracy of the trace.
“Mode” lets you easily toggle between color, black and white and grayscale settings.
“Palette” lets you decide how the colors will be chosen for the traced image. Your options are:
- Automatic: Automatically samples colors based on the image being traced, and switches between limited/full tone depending on the number of colors.
- Limited: Traces using a smaller, adjustable, palette of colors sampled from the image. Better for images with fewer colors.
- Full Tone: Uses a wide range of colors sampled from the image being traced. Better for photographs and images with many different colors.
- Document Library: Want your final image to have a different color palette than the source image? This allows you to import a custom color library for more control.
If your output is in color, then you will see the “Colors” slider. If your output is black and white, then you will see “Threshold” slider.
- The colors slider is a straightforward tool for setting the number of colors you want to have in the final traced image. The more colors, the more depth, and detail in the tracing. Fewer colors means a more flat, simple image.
- Threshold is a little different. When you are setting the threshold value you are assigning all pixels lighter than the threshold to white, and all pixels darker than the threshold to black. The higher the threshold, the darker the overall image, and vice versa.
The advanced settings are an extended set of features that you can use to have even more control over your traced image.
This feature lets you adjust how close the traced image paths get to the original pixels of the image. A lower value means less pixel variation (a tighter fit), and a higher value means more variation (a looser fit). A lower value can deliver a smoother, yet less accurate result, while a higher value delivers a more accurate, but often choppy result. Take a look at this closeup of our strawberry.
This slider decides when a sharp corner will be turned into a corner anchor point in your output image. A higher value means the tracing will have more sharp corner. A lower value means less corners, and more sharp curves.
This is minimum number of pixels needed for an area to be included in the tracing. The lower the number, the less pixels needed, so the more detailed (or noisy) the trace. The higher the number, the more areas will be ignored, and the simpler the image. You can see in the image below that the higher value does not pick up many of the seeds on the strawberry.
“Method” is a new addition in CS6, and it’s a great to have when tracing simpler images. You have two options for your tracing method:
- Abutting: Separates the different color fields and places them right up against one another, creating a nesting effect.
- Overlapping: Separates contiguous color fields into larger, overlapping, shapes.
Both options will yield the same initial visual result. The difference is in how the shapes are formed to create that result, and how they interact with one another.
The “Create” setting allows you to decide whether you want the tracing in fills (filled in areas of varying size), strokes (outlines of a fixed width), or both.
The reason that strokes can be useful is that it converts the image directly into single, editable paths. This can be helpful if you want to digitize a sketch with all the strokes being uniform, and have anchored paths to directly edit. In my experience the results are awkward at best, and, if you want single stroke editable paths, you might be better off using the pen tool to trace simpler shapes.
In the following example, the image on the left is my original image, and on the right is the result of tracing using strokes:
In the “Options” section of the image trace panel you will find these two check boxes:
- Snap Curves to Lines: This takes curves that are close to 0° or 90° and automatically snaps them into a straight line, or a right angle. This is good to have checked when you are working with geometric shapes and patterns.
- Ignore White: This one simply ignores any white in the image. Since most of us scan things in on white paper, or use an image with a white background as a source image, this option is great. It only takes the image that you are tracing into account so you can then place the traced image on any background without expanding and deleting the original white rectangle behind it.
The image trace panel is a useful tool that can be manipulated in a number of ways. Tracing a pixel based image is a basic skill that every designer needs to use at some point. I hope this overview has given you a confident understanding of the various functions of the image trace panel, and how you can use them to your advantage.