As Computex’s doors swing open today, NVIDIA is demonstrating a new technology for Tegra 4-based tablets that lets a fine-tip passive stylus be used to draw lines of different width simply by varying the pressure applied by the user.

The result is the first low-cost screen stylus that replicates the natural ease of writing – and erasing – directly on paper.

NVIDIA DirectStylus technology applies the image-processing power of Tegra 4’s GPU to analyze data from a standard touch sensor and recognize the difference between fine-tip stylus, finger, eraser and palm.

The result: Users can write on the screen using a simple passive pen and its opposite end can be used like an eraser, whose unique touch pattern can be differentiated from drawing strokes.

While passive styluses are available on the market, they generally have fat, 5mm tips that draw only one line width without the user selecting different stroke widths from a menu. These are of limited use, especially in Asian markets, where drawing characters requires line strokes of continually varying width.

Active 1.5mm styluses on the market that are capable of making strokes of varying width typically require a dedicated digitizer and cost at least $20. In contrast, the DirectStylus solution is an inexpensive passive conductive stylus.

DirectStylus works in conjunction with Direct Touch 2.0 technology which supports up to 300 scans a second (five times the typical 60Hz touch scan rate) to capture more detailed movement of the stylus for smooth ink and fine tip movement.