Skip to content
ArcBrush ArcBrush Docs

Posterize

Node icon
Color

Reduces the number of color levels for a flat, stylized look, with optional dithering.

The Posterize node applied to a source image: original (left) and result (right).
Side-by-side comparison: the original image on the left and the same image after the Posterize node on the right.

Each channel is snapped to evenly spaced levels on its own, so the color count grows fast: 4 levels allows up to 64 colors, 8 levels gives the classic poster look, and 256 passes the image through unchanged. Turn on Per Channel to give red, green, and blue different level counts.

Parameters

Section titled “Parameters”

Pins

ImagePixels
InputRequired
MaskMask
InputOptional
ImagePixels
Output

Color

LevelsInteger
Default: 32 Range: 2–256
When Per Channel is off

Distinct values per R, G, B channel. Applied independently to each channel, so total unique colors can be up to levels cubed (e.g. 2 = up to 8, 4 = up to 64). 8 = classic poster effect, 256 = no change (passthrough).

Per ChannelToggle
Default: false

Enable separate level controls for Red, Green, and Blue.

Off: all channels use the same number of levels.

Red LevelsInteger
Default: 32 Range: 2–256
When Per Channel is on

Distinct values for the red channel. 2 = on/off, 256 = unchanged.

Green LevelsInteger
Default: 32 Range: 2–256
When Per Channel is on

Distinct values for the green channel. 2 = on/off, 256 = unchanged.

Blue LevelsInteger
Default: 32 Range: 2–256
When Per Channel is on

Distinct values for the blue channel. 2 = on/off, 256 = unchanged.

DitherToggle
Default: false

Apply ordered (Bayer 4x4) dithering to reduce visible banding between color levels.

Creates a stippled pattern that simulates more colors than the level count allows.

Mask

Mask FromChoice
Default: Luminance
Color image connected to the mask input

How the connected color image is read as a mask

  • LuminanceRead the image's brightness as the mask. The default.
  • AlphaRead the image's transparency as the mask.
  • RedUse the red channel as the mask.
  • GreenUse the green channel as the mask.
  • BlueUse the blue channel as the mask.
Mask FitChoice
Default: None (native size)
Mask connected

How the mask is sized when it doesn't match the image

  • None (native size)Center the mask at its native size, with no resizing. Unmasked regions are unaffected.
  • StretchStretch the mask to exactly match the image dimensions. May distort the mask shape.
  • Fit (letterbox)Scale the mask to fit inside the image, preserving aspect ratio. Letterboxes where needed.
  • Fill (crop)Scale the mask to fill the image, preserving aspect ratio. Crops edges if aspect ratios differ.

Usage Tips

Section titled “Usage Tips”
  • 2 to 4 levels gives bold graphic color; 8 to 16 is a subtle stylization.
  • Turn on Dither at low level counts to trade banding for a fine stipple.
  • Posterize spaces its levels evenly per channel. To reduce to colors picked from the image itself, use Quantize instead.
  • Wire a mask to posterize only part of the image.
Section titled “Related Nodes”