How does the tool decide which pixels to recolor?

It measures the Euclidean distance between each pixel's color and the source color you enter. Any pixel within the tolerance you set gets replaced with the target color; everything else is left as-is.

What happens to anti-aliased edge pixels?

Edge pixels that are a blend of ink and background often fall outside a low tolerance and stay unchanged, which can leave a faint fringe of the old color. Raising the tolerance slightly usually catches them too.

Does this change the signature's transparency?

No. Only the RGB color of matched pixels changes; each pixel's original alpha value is left untouched.

Can I use this to change more than one color at once?

Each run targets one source color. Run the tool again with a different source color if your signature has multiple ink tones to change.

Signature Color Changer - Recolor Ink in a PNG Signature

Overview

Introduction

This tool changes the color of a signature's ink in your browser, matching pixels close to a source color and replacing them with a target color.

It's a direct, general-purpose recolor tool, useful whenever the built-in blue/black ink presets don't fit what you need.

What Is Signature Color Changer?

A client-side color-replacement tool built on Euclidean color-distance matching in RGB space.

Given a source hex color, a target hex color, and a tolerance, it recolors every close-enough pixel while leaving the rest of the image untouched.

How Signature Color Changer Works

For each pixel, the tool computes the squared distance between its RGB values and the source color's RGB values, then compares that against the squared tolerance. A match gets its RGB channels replaced with the target color; alpha is always preserved.

A tolerance of 0 only matches an exact color; larger tolerances catch anti-aliased or slightly varied shades of the source ink.

When To Use Signature Color Changer

Use it to match a digital signature's ink color to a specific brand color or house style.

It's also handy for correcting a signature that was scanned with a color cast, once you know roughly what color the ink actually is.

Often used alongside Signature to Blue Ink Converter and Signature to Black Ink Converter.

Features

Advantages

Works with any source and target color, not just presets.
Preserves the original alpha channel so transparency is unaffected.
Runs entirely in the browser.

Limitations

A low tolerance can miss anti-aliased edge pixels, leaving a thin fringe of the old color.
A high tolerance can accidentally recolor unrelated pixels that happen to be similar in color to the ink.

Examples

Black ink to a brand blue

Input

Source #000000, target #0f4c81, tolerance 40

Output

Every near-black pixel becomes the brand blue, background untouched

A moderate tolerance catches anti-aliased dark-gray edge pixels along with the pure black core.

Exact color swap

Input

Source #1a1a1a, target #ff0000, tolerance 0

Output

Only pixels that are exactly #1a1a1a become red

A zero tolerance is useful when you know the exact ink color and want a precise, surgical replacement.

Best Practices & Notes

Best Practices

Sample the signature's actual ink color with an image editor's color picker before entering the source color.
Start with a moderate tolerance (20-40) and adjust based on how much fringe is left behind.

Developer Notes

This tool is a thin wrapper around the general-purpose changePngColors function; the underlying color-distance matching math is identical regardless of whether the subject is a signature, logo, or any other PNG.

Signature Color Changer Use Cases

Matching a digital signature's ink color to a company's brand palette
Fixing a signature scanned with an off color cast
Standardizing ink color across multiple signature assets

Common Mistakes

Entering the wrong source color, which causes no pixels to match and nothing to change.
Using a tolerance so high it recolors parts of the background that happen to be near the source color.

Tips

If part of the ink is left unchanged, increase the tolerance a little rather than jumping straight to a very high value.
Preview the result before downloading; the checkerboard background makes it easy to spot leftover fringing.

Signature Color Changer