How to render text with 1px stroke width at small sizes for embedded displays?

[dortegacee]

Context

I'm rendering text onto small monochrome OLED displays (SSD1305/SSD1306, 128×32 and 128×64, 1bpp) using SixLabors.ImageSharp.Drawing v2.1.7 with SixLabors.Fonts v2.1.3 and SixLabors.ImageSharp v3.1.12, targeting .NET 10.

On these displays, legibility requires character strokes to be exactly 1 pixel wide. At small font sizes (8–13pt), system fonts like Arial produce strokes that are 2–3px wide, making text look overly bold and hard to read at these resolutions.

What I've tried

1. Brushes.Solid() fill (default)

canvas.Mutate(ctx => ctx.DrawText(
    drawingOptions, textOptions, text,
    Brushes.Solid(fgColor),
    null));

Fills the glyph interior — strokes are 2–3px wide at small sizes because that's how the font outlines are designed.

2. Pens.Solid() stroke with small width

canvas.Mutate(ctx => ctx.DrawText(
    drawingOptions, textOptions, text,
    null,
    Pens.Solid(fgColor, 1f)));

This strokes the boundary path of the glyph fill region (the outline contour), not the stroke centerline. For a letter like "I", this traces both the left and right edges of the stem, producing double lines rather than a single thin stroke. Values below 1f (e.g., 0.2f) still produce multi-pixel results.

3. Embedded pixel font (current workaround)

We switched to an embedded pixel .ttf (CozetteVector) whose glyph outlines are designed as exact pixel-aligned rectangles. At the font's native size, Brushes.Solid() fill produces 1px strokes because the outlines physically span only 1 pixel. This works, but it limits us to specific bitmap fonts at fixed sizes.

The question

Is there a way within ImageSharp.Drawing to achieve 1px stroke rendering from standard vector fonts at small sizes?

TrueType hinting support in SixLabors.Fonts — Is there a planned feature to implement a TrueType bytecode interpreter that would enable grid-fitting? This would be the most direct solution.

Manual glyph path access — Is there a way to access the raw glyph IPath objects and apply custom transforms (e.g., scaling + quantizing control points to pixel grid) before rasterizing?

Any other workaround besides bitmap fonts for achieving pixel-crisp stems at small sizes?

Environment

• SixLabors.ImageSharp 3.1.12
• SixLabors.ImageSharp.Drawing 2.1.7
• SixLabors.Fonts 2.1.3
• .NET 10
• Target hardware: SSD1305/SSD1306 128×32/128×64 monochrome OLED displays

[JimBobSquarePants]

For reference, SkiaSharp's SKPaint.IsStroke = true with StrokeWidth = 1 achieves this because Skia internally extracts the glyph stroke skeleton/centerline and draws that, rather than stroking the fill boundary path.

Do you have documentation that supports this because this goes against expected behaviour.

[dortegacee]

Thank you for the response! My mistake (blindly followed AI), that's inaccurate. What actually happens is that with default Fill style, Skia delegates glyph rasterization to the platform font engine (DirectWrite on Windows). DirectWrite applies the font's TrueType hinting instructions, which snap stem widths to whole pixel boundaries — at TextSize 14, a ~1.37px stem (200/2048 em-units × 14) gets grid-fitted down to 1px.

1px looks great on 128x32 displays at smaller fonts. I'm able to achieve something similar if I manually load other fonts (currently using Tamzen fonts). Do you know if SixLabors rasterization does something similar? From reading other discussions, it seemed like you recently implemented hinting, but when using Arial (same font as I'm using in skia) it does not snap to the nearest pixel or keep it 1px wide as skia does.

From reading your code, it doesn't seem like you guys use TrueType Hinting, and instead would render a stem at it's fractional width and use Anti-Aliasing to blend across 2 pixels instead of rounding up or down to 1px or 2px.

[JimBobSquarePants]

From reading your code, it doesn't seem like you guys use TrueType Hinting, and instead would render a stem at it's fractional width and use Anti-Aliasing to blend across 2 pixels instead of rounding up or down to 1px or 2px.

I fear you may have been misled by AI again. Hinting affects how glyph shapes are returned by the Fonts library which our drawing library will use to render a glyph when hinting is enabled via options.

The latest hinting engine improvements are not available to the public drawing library yet. You can however try the nightlies stream references in our repository readme.