Halftone Comic/Print is a Paint.NET effect plugin by RedKnack Interactive that simulates real offset print and comic book halftone screens via SDF-based dot rendering.
- Paint.NET: tested with 5.x
- Language: C# / .NET 9
- Location: Effects → Stylize → Halftone Comic/Print
- CMYK 4-screen separation with independent per-channel screen angles
- 8 dot shapes: Circle, Diamond, Square, Line, Cross, Ellipse, Euclidean, Ring
- 4 tone curves: Area Proportional, Linear, Gamma, Sine
- SDF-based rendering with configurable soft-edge anti-aliasing
- Black point / white point tone remapping
- 1–4x oversampling
- Alpha-preserving output
- Build the project or download the release DLL.
- Copy
RedKnack.HalftonePlugin.dllinto your Paint.NET effects folder:C:\Program Files\paint.net\Effects - Restart Paint.NET. If necessary.
| Parameter | Range | Default |
|---|---|---|
| Cell Size | 2 – 120 px | 20 |
| Dot Shape | Circle … Ring | Circle |
| Tone Curve | Area Proportional … Sine | Area Proportional |
| Color Mode | Grayscale / CMYK / Spot / RGB | CMYK |
| Screen Angle | 0 – 179° | 45° |
| Cyan / Magenta / Yellow / Black Angle | 0 – 179° | 15° / 75° / 0° / 45° |
| Edge Softness | 0 – 10 px | 1.5 |
| Min / Max Dot Size | 0 – 100% | 0% / 95% |
| Invert | bool | false |
| Ring Width | 0.05 – 0.95 | 0.3 |
| Background Color | RGB | 255, 255, 255 |
| Spot Color | RGB | 0, 0, 0 |
| Black Point / White Point | 0–49% / 51–100% | 0% / 100% |
| Oversampling | 1 – 4 | 2 |
The technical background on printing principles and rendering techniques.
Traditional printing cannot reproduce continuous tones and ink is either on paper or not. Halftone screening solves this by converting tonal values into a grid of variable-size dots. A darker area produces larger dots that cover more paper; a lighter area produces smaller ones. From a reading distance, the eye averages the ink/paper ratio back into a perceived tone, kinda like RGB-Pixels.
This plugin replicates that grid geometry exactly: each output pixel is assigned to the nearest cell center in a rotated coordinate grid, the source image is sampled at that center, and the result drives the dot radius.
Full-color offset printing uses four ink layers: Cyan, Magenta, Yellow, and Black (Key), so CMYK. Each is printed as its own halftone screen at a different angle to prevent the dots from stacking and creating a muddy moiré . The slight misalignment between the four screens produces the characteristic rosette pattern visible under magnification in any printed magazine or comic.
The default angles (C=15°, M=75°, Y=0°, K=45°) match the real-world press standard. Compositing is subtractive: cyan ink absorbs red light, magenta absorbs green, yellow absorbs blue, so the same physical absorption model as actual ink on paper.
The K channel uses GCR (Grey Component Replacement): neutral grey components present in all three CMY channels are replaced by a single black ink hit, reducing ink consumption and improving shadow detail, the same optimization used in professional print workflows.
Each dot shape is defined as a Signed Distance Field - a mathematical function that returns the signed distance from any point to the nearest edge of the shape (negative = inside, positive = outside). This means dot boundaries are not hard-aliased pixel edges but smooth, resolution-independent curves. The soft_edge parameter controls a smoothstep transition zone around the zero crossing, producing sub-pixel anti-aliasing at no extra sampling cost.
The Euclidean dot blends between a circle SDF and a square SDF based on the current dot density. At low coverage it reads as isolated circles; at high coverage it fills in as a square, leaving circular white holes, identical to the classic Euclidean spot used in high-fidelity print reproduction. This transition is what generates the most accurate rosette geometry in CMYK mode.
The relationship between measured tone and physical dot size, other than i thougth, is not linear in print:
- Area Proportional → dot area scales linearly with tone value (
r = r_max x √vorr equal r_max times squareroot of v). Perceptually correct for print: a 50% tone value covers exactly 50% of the cell area. - Gamma (2.2) → compensates for display gamma, producing visually balanced output when the source image is intended for screen.
- Sine → compresses the response at both ends, producing very soft transitions in highlights and shadows.
The source image is not sampled at a single point per cell! A box filter averages all pixels within a region proportional to the cell size. This prevents single-pixel noise from creating isolated outlier dots and ensures each dot represents the actual local tone of that print cell, matching how a real world scanner or plate-making system would measure film density (Like on thoose roll-thingies).
MIT License, see LICENSE.
NONE, NADA, NIENTE