Background Colour Replacer

About this tool

Replacement works on a mask: transparency mode marks every pixel below your opacity threshold, while pick mode measures each pixel's RGB distance from the target colour and either scans the whole image or flood-fills only the connected region you seeded. The mask is then blurred by the feather radius and used to blend the original pixels with the fill.

The fill can be a solid colour, an angled linear gradient, or a two-tone checkered pattern. Images are processed at up to 1600px on the long side, and the preview and the downloaded PNG come from the same pass, so what you see is what you get. Nothing is ever uploaded.