Buzz
To convert a raster (bitmap) graphic image into a vector format using Inkscape, you need to trace the image. Fortunately, Inkscape comes with an integrated auto-tracing tool, eliminating the need for advanced skills or extensive time investment. For more precise control over the tracing process, you can utilize Inkscape's built-in drawing tools to manually trace the image. Regardless of the method you choose, Inkscape simplifies the process of vectorizing bitmap images.
Steps
Auto Tracing
Import the image. Click on 'File' in the menu bar, then select 'Import'.
Open the tracing tool. To access Inkscape's tracing tool, click on 'Path' in the menu bar and select 'Trace Bitmap'.
Choose between single and multiple traces. Select 'single' for a single trace or 'multiple' for overlapping traces on the image.
- Single trace options:
- Brightness cutoff uses pixel brightness to determine whether the trace should be black or white. A higher threshold results in a darker image.
- Edge detection creates traces based on differences in pixel brightness. The threshold setting controls the darkness of the output image. Again, a higher threshold yields a darker result.
- Color quantization generates traces based on color differences. The 'number of colors' setting allows you to specify the desired number of colors in the output image, which are then converted to black or white using an algorithm.
- Multiple trace options:
- Brightness steps lets you define the total number of traces.
- Colours uses the 'Scans' field to determine the number of colors in the output image.
- Grays works similarly to colors but is based on grayscale shades.
- Additional options: 'Smooth' applies a Gaussian blur before tracing, while 'Stack scans' removes gaps in trace coverage. Check 'Remove background' to eliminate the background (usually the lightest color).
- Other options:
- 'Suppress speckles' removes unwanted dots, dust, distortions, or other artifacts.
- 'Optimize paths' merges Bezier curves for smoother results.
Click 'Update' to preview the result. If the trace is too bold or not prominent enough, you may have chosen an unsuitable tracing mode for the image. Inkscape recommends using the tracing tool three times to determine the best option for your needs.
Click OK to create the trace. The bitmap image will remain in the SVG file.
Edit and refine the output: Click the 'Edit paths by nodes' button on the left (or press F2) to adjust nodes and curves.
Manual Tracing
Import the image. Click on 'File' in the menu bar, then select 'Import'.
Open the Layers dialog. While technically optional, tracing on a new layer allows you to see your progress by adjusting the transparency settings of the image (or tracing layer). Click on 'Layer' in the menu bar and choose 'Layers'.
Add a new layer. Click the '+' sign to create a new layer. Name the layer (e.g., 'tracing layer') and set its position to 'Above current'. Click 'Add' to confirm.
Select the tracing tool. Inkscape offers various tools for different needs.
- Press the F6 key (or click the pencil icon in the toolbar) to select the pencil/freehand tool. This tool lets you draw freely anywhere on the image. It's ideal for tablets, steady hands, or images with minimal detail.
- Press Shift+F6 (or click the pen icon in the toolbar) to open the pen/Bezier tool. This tool allows you to create short, manageable strokes. It's perfect for detailed work or when using a mouse. Double-click at the end of each stroke to finish.
Using a tablet or mouse, trace each line in the image. If you choose the pen tool, opt for short strokes instead of continuous long lines. This makes the graphic easier to edit, as you won’t need to redraw lengthy strokes if minor errors occur at the last moment.
- You can switch between layers in the Layer dialog. Simply double-click the name of the layer you want to work on to switch to its view.
- While tracing, you can control how much the bitmap image is faded. With the selected layer in the dialog, adjust the slider under the 'Opacity' heading to find the most suitable setting.
Open the 'Edit Node' tool. In the tool menu, click the second arrow from the top (the 'edit' arrow) to activate editing mode. In this mode, you can click and drag nodes to refine the paths.
- If there are too many nodes, making it time-consuming to position them correctly, you can simplify the number of nodes. This may slightly alter the shape of the path, but the change is minimal. Use the shortcut Ctrl+L (⌘ Cmd+L on Mac) to reduce the number of nodes.
Review the graphic without the bottom layer. To ensure all desired lines have been traced in the vector image, click on the first layer (the raster image) and reduce its opacity until only the traced lines remain. If you notice any missing lines, return to the layer tool and increase the opacity to reveal the areas that need tracing.
Delete the bottom layer and save the image. In the layer tool, click on the first layer (containing the original image) and delete it by clicking the minus icon. To save your graphic, click on File and select Save As.
Tips
- Removing the background from a bitmap image before converting it to a vector enhances the quality of the traced lines. Experts recommend using SIOX to eliminate the background from bitmap images before starting the tracing process.
- Generally, bitmap images with multiple colors and gradients demand higher precision than what automatic tracing tools can provide.
