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Laser Engraving and Cutting

A guide to PPLD's laser engravers/cutters

What is Vectorization?

Vectorization is the process of converting a raster image into a vector line by having a computer program "trace" the image and automatically create vector lines. Most programs that can work with vector lines have methods for doing this automatically, however they all function differently and some images will work better in one program over others.

Vectorization concept

Generally speaking, black and white images are the easiest to vectorize, as all the program has to do is draw a line along the border between any black and white pixels. Images with more complex color scheme can still be vectorized, however you will have to tell the program more information about how to determine where the lines are drawn. Also, be aware that with highly complex images (such a photographs) it may not be possible to have a program handle the vectorization automatically.

How to Vectorize..

Each of the following guides assumes that you have a basic understanding of how the software works. Please see the Software for Creating Images page for more information on these programs and how to learn to use them.

Select the software that you will be using from the tabs.

Illustrator offers a variety of automatic tracers, which work well for a variety of image types. The default tracer works well with monochromatic images where you want everything converted to a vector image.

  1. File > Place the image into Illustrator and make sure the image is selected.
  2. Click "Image Trace" and select the preset that best matches the type of image you are working with.
  3. Click Expand (this will complete the trace).
  4. Adjust the Stroke thickness to .001.
  5. If the new vector line is useable, continue setting up the vector cut normally. Otherwise undo the conversion and try again with a different preset. If no settings work, try manually creating the vector lines.

Tracing in Adobe Illustrator

Inkscape offers two types of vectorization - Single Scan, which creates a single path that traces the image, and Multiple Scans, which creates a full color (but simplified) image out of multiple vector shapes. Single Scan is generally the best way of creating vectors that will be used for cutting.

  1. Import the image into Inkscape (keep all default options) and select the image.
  2. Under the Path menu, select "Trace Bitmap".
  3. Turn on Live Preview to get a constantly updated preview of what your vectorized image will look like. If it is not turned on, click the Update button to refresh the preview window.
  4. There are a variety of options that can help smooth out lines, especially if the raster image is small or contains jagged lines, but for the most part, the only thing that needs to be adjusted is Brightness Cutoff or Edge Detection and the Threshold values for each.
    1. Edge Detection and Brightness Cutoff are very similar and often produce the same results. If one is not giving you the results you want, try the other one.
    2. Threshold adjusts how much of a difference there has to be between two adjacent pixels for it to count as a separate part of the image. Lower values generally produce more lines.
    3. A pure black and white image will almost always vectorize perfectly with either setting at a threshold of 0.500.
  5. When the preview looks correct, click the OK button - your image is not actually vectorized until you do this.
  6. Close the window by clicking the X in the upper right corner.
  7. Move or delete the raster image to be able to see the vector images.
  8. If the vector image does not work properly, undo it and try different settings.

Trace Bitmap Options

  1. Turn on Live Preview
  2. Select Edge Detection or Brightness Cutoff
  3. Choose Threshold level
  4. Click OK
  5. Click the red X to close the window

Now you are going to set the line width of your image. The outline that you want to cut needs to have a line width of .001 in. To change this, you need to click on the image. Go to Object > Fill and Stroke. On the Fill tab, click the No Paint box. Go to the next tab, Stroke Paint. Click the Flat Color box. Click on the last tab, Stroke Style. Change Width to .001 in. Also, make sure that the Opacity is set to 100%.

CorelDRAW offers both a fully automatic tracing and a suite of presets designed for various types of images. Generally speaking, the automatic Quick Trace works well for monochromatic images where you want everything converted to a vector image. The presets work better for more complex images.

  1. Import the image into CorelDRAW and make sure the image is selected.
  2. Click "Trace Bitmap".
    1. For the fully automatic tracing, select "Quick Trace".
    2. For more options, select any of the options under "Centerline" or "Outline Trace" and a new window will appear with a variety of options.
      1. "Trace Type" and "Type of Image" will let you load any of the presets that were available in the Trace Bitmap menu.
      2. "Detail" adjust the threshold of what is converted to vector lines - if not enough of the image is show in the preview, adjust this slider.
      3. "Smoothing" and "Corner Smoothness" make jagged edges more round.
      4. "Delete original image" will remove the bitmap from CorelDRAW (but not the separate saved file that was imported).
      5. The other options impact how the software sorts and groups the new vector shapes.
      6. Click "OK" to convert the bitmap and return to the main area of CorelDRAW.
  3. If the new vector line is useable, change the line thickness to Hairline and setup a vector cut normally. Otherwise undo the conversion and try again. If no settings work, try manually creating the vector lines in GIMP.

Tracing in CorelDRAW

 

CorelDRAW tracing options

 

This works best for monochromatic images where you want every region or a closed outline converted to vector lines.

  1. Open the image in GIMP.
  2. Using the selection options, choose the regions to outline (you can select more than one region if needed).
    GIMP section options (square, oval, lasso, fuzzy, color)‚Äč
    From left to right:
    1. Rectangular
    2. Oval
    3. Lasso / Freehand
    4. Fuzzy (continuous regions of the same color)
    5. Color (all of the same color, regardless of location)
  3. If the region selected includes the border of the image, you can set it so that it does not draw a vector box around the image by going into the "Select" menu and choosing "Invert".
  4. In the "Select" menu, choose "To Path".
  5. In the Layers Dock, select the Paths tab (third one from the left).
    GIMP path menu area
  6. Right-click on the path and choose "Export Path".
  7. Pick a place to save it and give the file a name (be sure to include .svg).
  8. You can now bring that file into Illustrator for cutting.
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