Online Image Duotone Effect Tool

What this tool actually does

Two native color pickers map shadows and highlights. Defaults are shadow #111827 (RGB 17,24,39) and highlight #22D3EE (RGB 34,211,238). An Invert colors checkbox is off by default. There is no midpoint, curve, blend-strength, gradient-stop or selective-area control.

Checkable behavior

For every pixel, weighted luminance q=(0.299R+0.587G+0.114B)/255 selects a linear position between the two chosen colors. Invert replaces q with 1-q. Alpha is not changed by the mapping.

Controls, output and limitations

With the defaults, black maps to #111827 and white maps to #22D3EE. Verified example: RGB(100,150,200) maps to approximately RGB(26,127,149); with Invert selected it maps to approximately RGB(25,108,128), after byte rounding.

The result contains mixtures of two endpoint colors according to luminance; it is not a two-color threshold, indexed-palette reduction, spot-color separation or preservation of original hues. Different source colors with the same weighted luminance map to the same duotone color. Keep the original.

Load one image, choose shadow and highlight colors, optionally invert, press Generate and inspect light and dark detail, then download PNG. Press Generate after control changes. Processing is browser-local and applies to the whole image; no live automatic preview or batch selector is provided on this page.