Stencil Drawing – C# code and Stencil Maker

Online Stencil Maker

If you need to turn your photos or images into stencils, use our free online tool! It creates image stencils and allows you to vectorize them for scalable and clear vector graphics. Stencil Maker supports many image formats, including JPEG, JPG, PNG, BMP, ICO, GIF, TIFF, WEBP, SVG, and more.

What is an image stencil?

Image stenciling is a process that turns an ordinary picture or photo into an outline image that can be used as a stencil for graffiti-like effects. There are several basic steps for turning a photo or image into a stencil:

• Convert a photo or image to grayscale, this step is optional, as you can reduce the number of colors to quantize instead.
• Quantize image colors to simplify the image, after that you can download the result or vectorize it and get the stencil shape lines.
• There are three options for drawing stencils. The first is “None” when all the vectorized shapes are filled, the second is “Auto” when the shapes are not filled and the borders have the “original” color, and the last is “MonoСolor” when the shapes are also not filled, but the borders have the predefined color.
  

How to use Image Vectorizer?

1. Load your source raster image from your local file system. The UI presents three panels: Source Image, Quantized Image, and Vectorized Image.
2. The engine evaluates the Image using default properties. To optimize the SVG output, use the sidebars to tune the quantization and vectorization parameters. Click Quantize to preview palette reduction, then Vectorize to render the SVG paths.
3. Click Download to save the generated vector file.

Quantization Options

Adjust these settings to govern how the algorithm groups pixels and reduces the initial color palette:

• colors - Sets the exact maximum palette size constraint.
• method - Switches between histogram-based color quantization algorithms.
• minHueCols - Controls sensitivity limits for handling color gradients.
• scale - Adjusts the scaling factor for finer or coarser color sampling.
• grayscale - Forces the output to monochromatic boundaries.

Vectorization Options

Control the geometric tracing behavior applied to the quantized map:

• threshold - Defines the pixel sensitivity constraint for detecting boundary contours.
• severity - Modifies contour smoothing using Nearest Neighbor spatial sizing.
• line-width - Determines the stroke thickness assigned to generated SVG lines.
• stencil - Applies a binary outline mask, ideal for converting continuous-tone photographs into stenciled silhouettes.
• trace paths - Toggles the visual rendering of the Bezier curve and spline control points used to build segments.
  
  

How to Make Stencil in C#

You can easily integrate stencil effects into your image vectorization workflow using C#. By utilizing the ImageVectorizer class and the StencilConfiguration object, you can define specific stencil types and colors to produce highly customizable, professional-grade vector graphics.

    // Initialize an instance of the ImageVectorizer class
    ImageVectorizer vectorizer = new ImageVectorizer
    {
        // Optionally set a configuration
        Configuration =
        {
            // Optionally create an instance of the PathBuilder class
            PathBuilder = new BezierPathBuilder 
            {
                // Optionally set trace smoother
                TraceSmoother = new ImageTraceSmoother(1),
                ErrorThreshold = 30,
                MaxIterations = 30
            },
            ColorsLimit = 10,
            LineWidth = 1,
            // Set stencil effect configuration
            Stencil = new StencilConfiguration { Type = StencilType.MonoColor, Color = Aspose.Svg.Drawing.Color.FromRgb(0,0,255) }
        }
    };
    
    // Vectorize image from the specified file
    using (SVGDocument document = vectorizer.Vectorize(Path.Combine(DataDir, "image.png")))
    {
        // Save the vectorized image with the stencil effect as an SVG file
        document.Save(Path.Combine(OutputDir, "image-stencil.svg"));
    }

Steps to Make Stencil in C#

You can create a stencil from any raster image using Aspose.SVG by following these three steps:

1. Initialize the ImageVectorizer and access its Configuration to set up your rendering options.
   • Set up a PathBuilder that will trace the smooth vector curves.
   • Define your ColorsLimit explicitly (e.g., 10) to simplify the source image and prepare it for tracing.
   • Configure the Stencil property (like StencilType.MonoColor) to tell the API exactly how to draw the final outlines.
2. Pass your image file to the Vectorize() method to process the graphics into a fully vectorized SVGDocument.
3. Save the resulting stencil to your file system using the basic Save() command.

To get a complete overview of the vectorization architecture and see more examples of how to configure image tracing, check out the Vectorization – Basic Overview documentation. This guide walks you through the core concepts of replacing raster images with mathematically scalable vector paths, including how to process formats like PNG, JPG, BMP, TIFF, GIF, and ICO into SVG documents.

FAQ

Get Started with Aspose.SVG for .NET API