Use Case

Stylus Devices

What does Astui solve?

For many years, stylus input devices for computers were relatively niche. The most recognisable supplier of physical products has traditionally been Wacom, who developed and continuously evolved their tablets which have been universally adopted by designers.

More recently, new mass market devices have entered the desktop market promoting the use of styluses instead of (or in addition to) trackpads, mice and touch. These include Microsoft’s Surface and Apple’s iPad, which have boosted the awareness and adoption of the stylus to use as a primary input for designers.

Due to their physical attributes, the stylus has always been seen as an intuitive and natural device for artists producing painterly style work or editing photos/photorealistic raster-based images. With pressure, orientation, angle and other potential multi-level inputs (as opposed to a mouse or trackpad’s “on/off” button type), their translation to digital brush strokes is well proven.

What has been much less utilised for 2D artwork is fully integrating all the benefits of stylus input for vector artwork creation. Basic Pencil-type tools, which translate mouse, trackpad and other user inputs into Bezier paths, have been available for decades with varying levels of quality and refinement. However, translating the stylus’ simultaneous and variable pressure angle and orientation channels into high quality vectors is currently rudimentary or completely missing.

This absence of solutions is likely due to the extreme complexity of the technology involved to generate humanly-editable and high-quality results. This is especially true without the addition of thousands of unnecessary and intrusive control points along each path to gain a reasonable representation of user intent.

What Astui solves is the generation of very high-quality and visually representative vector paths or outlined shapes, which fully utilises and benefits from the stylus’ trace (the shape the user is drawing) and optionally the device’s pressure, angle and/or orientation. Each resultant path is automatically fully optimised to ensure a minimum number of professionally positioned (including the Clockwise Method) Bezier points to ensure full human editability.


Astui features core technologies (accessible via a web-API or embedded instance) which can be used individually or in combination using the Recipe mechanism to produce vectors based on a stylus input:

  • Path Fitting – translates the X/Y input trace of the user’s input to vector paths
  • Variable Stroke Widths – translates the pressure inputs to outlined vector shapes
  • Vector Brushes – add natural appearance or graphic styles to results
  • Outline Stroke – useful if Variable Stroke Widths and/or Brushes are not deployed to optionally convert the resultant path into a basic shape
  • Boolean – the option to combine successive outlined strokes (uniform or variable width), or vector brush results to reduce excessive total artwork file size and rendering overhead
  • Smart Point Removal and Cleanup – optional post-processing operations to further enhance results dependent on the requirements of the software and user expectations (for example, putting control points at horizontal and vertical tangencies where possible)

This solution is ideal for developers looking to add high-quality vector sketching and drawing tools for desktop and mobile devices. With Astui being available via the web-API, it’s instantly accessible for all web-enabled systems. There is also the option to licensing Astui as a locally-hosted module within your solution, bringing the benefit of near-realtime results catering for “live” creative features including editable and un-expanded Variable Stroke Widths.

A second tool variant is also possible using Astui. Its function is demonstrated in the innovative Width Brush Tool in Astute Graphics’ WidthScribe plugin for Adobe Illustrator. This tool allows users to edit the variable width of any existing (non-outlined) path using the stylus’ pressure levels. A similar tool would not require the Path Fitting API, but would make direct use of the Astui Variable Stroke Width API.

Research is currently underway into direct support of the W3C industry-standard InkML and Wacom’s proprietary WILL mechanisms in Astui. This would further reduce development resource requirements to implement Astui for your solution. Please contact us if you are interested in the integration with either InkML and/or WILL.


  • Speed to deployment
  • Results returned in 2D vector artwork industry-standard Cubic Bezier curves
  • Quality of vector results including:
    • Accuracy of representation
    • Minimum Bezier point count
    • Corner detection and placement
    • Automatic clean-up of inputs affected by input types (eg. stylus’ user “lift” artifacts at the start and end of traces)
    • Humanly-editable ensuring excellent user workflow
  • Options to combine with post-processing Astui functions in a single Recipe request
  • Optional settings to enhance results based on user expectations for application (eg. accuracy and smoothness)
  • Open and modern web-API
  • Licensing option for allow for local embedding of technology on any platform

Existing Example

Astute Graphics, the developers of Astui, have been refining their path fitting solutions since 2012, when the DynamicSketch tool was first released for Adobe Illustrator. This product demonstrates the core quality of results, much of which became the underlying power behind the Astui path fitting functionality.

Note: some functionality demonstrated in DynamicSketch, including path trimming and repeat sketching, are the result of higher-level mechanisms which Astui assists with, but doesn’t deliver explicitly.