Free web tool
Replace pixels near a chosen source color with another color to change a simple background.
Replace pixels close to a selected background color with another color. It works best on flat or nearly flat backgrounds where color similarity is a reasonable way to identify the background.
The tool only measures RGB color distance. If the subject contains colors similar to the selected background, those subject pixels can also match.
It is most predictable for flat studio backgrounds, product shots, and scanned artwork where the background is fairly uniform.
Color distance is calculated from the differences in R, G, and B. Tolerance 0 matches only the exact RGB color; larger values admit increasingly different colors.
v1.49 labels the metric “matched pixels,” not “replaced pixels,” because feathering can make some matched pixels change only slightly.
Increasing feather reduces the replacement strength for pixels farther from the chosen source color. It is not detecting hair, silhouettes, or semantic object boundaries.
When subject and background colors overlap, start with a small tolerance and increase it gradually.
The operation changes RGB but leaves the original Alpha channel intact. Transparent input regions therefore remain transparent.
Use Image transparency / Alpha checker when you need to distinguish a colored background from true transparency.