Greyscale & Posterize

Greyscale converts the surface to luminance; Posterize quantizes each channel into a small number of steps. Together they cover retro 8-bit palettes, painterly comic looks, and runtime state grading such as frozen or broken visuals.

When to use it

Comic look — Posterize 3–5 with Outline.
Retro and 8-bit aesthetics — Posterize 2–4 with a tight palette.
Frozen or dead states — greyscale 1.0 at runtime via script.
Painterly look — a light posterize (8–12) softens gradients without crushing them.

Difference from Cel Shading

Cel Shading quantizes the lighting (NdotL). Posterize quantizes the final color, including albedo. Stack them for a fully stylized look — cel handles the light shapes, posterize handles the color bands.

Modes

Greyscale — lerps the surface toward luminance. Useful for state changes such as frozen, dead, or paused.
Posterize — quantizes each RGB channel into N steps. Two steps gives a hard 8-bit read; sixteen is subtle.

Continuous PBR color with smooth gradients.

Four color bands per channel plus an ink outline — an instant comic look.

Default

Posterize 4 + Outline

PBR against the canonical comic stack. Drag to compare.

Properties

Inspector label	Shader property	Type	Default	Description
Greyscale Amount	_GreyscaleAmount	Float (0–1)	0.0	Lerp to luminance. 0 = color, 1 = full grey.
Posterize Levels	_PosterizeLevels	Int (2–16)	16	Steps per channel. 2 = hard, 16 = subtle.
Posterize Amount	_PosterizeAmount	Float (0–1)	0.0	Blend between continuous and quantized.
Posterize Gamma	_PosterizeGamma	Float (0.1–4)	1.0	Gamma curve applied before quantization.
Quantize Mask	_QuantiseMask	Texture2D	white	Mask restricting the effect to UV regions.

Usage

For the comic look, set Posterize Levels to 3–5, Amount to 1.0, then enable Outline.
For a subtle painterly result, set Levels to 8–12 and Amount to 0.4.
For a frozen or dead state, animate Greyscale Amount from 0 to 1 over half a second.
Mask the effect to keep skin and eyes colored on an otherwise posterized character.


StartCoroutine(LerpFloat(material, "_GreyscaleAmount", 0f, 1f, 0.4f));
material.SetInt("_PosterizeLevels", 4);
material.SetFloat("_PosterizeAmount", 1.0f);

Tips & gotchas

Posterize runs after lighting, so band edges follow the shading and may shift as the camera moves. Use Cel Shading for bands locked to NdotL.
Greyscale followed by Hue Shift has no effect — you cannot shift the hue of a color already stripped to grey.
Bloom amplifies banding; drop posterize levels by one if you run heavy bloom.
Posterize costs roughly three ALU per channel, which is negligible on mobile.

Cel Shading — quantize lighting too.
Outline — finish the comic stack.
Hue Shift — pair with posterize for palette mapping.
Color Adjustments — smoother grading alternative.