How is this different from a grayscale stamp?

Grayscale keeps many shades of gray between black and white; this tool thresholds every pixel to exactly one of two colors, pure black or pure white, based on whether its brightness is above or below the threshold.

How do I control which pixels become black versus white?

Adjust the threshold value (0-255); pixels with perceptual luminance at or above it become white, and pixels below it become black.

Does this affect the stamp's transparency?

No, alpha is taken from the replacement color used internally, but since both black and white are set fully opaque by default, existing transparency in the source is not specifically preserved by this particular tool — flatten first if you need to keep a transparent background.

Why would I want a stamp in pure black and white?

It's the cleanest format for a stamp-style graphic meant to look like actual ink on paper, and it compresses smaller than a full-color or grayscale version.

Black and White Stamp Creator - Threshold a Stamp to Pure B&W

Overview

Introduction

This tool converts a digital stamp to true black-and-white entirely in your browser, using a brightness threshold rather than smooth grayscale shading.

The result looks like classic stamped ink: every pixel is either fully black or fully white, with no in-between tones.

What Is Black and White Stamp Creator?

A client-side thresholding tool that computes each pixel's perceptual luminance (using standard ITU-R BT.601 weighting) and compares it to a threshold value.

It reuses the same two-color conversion this site's general PNG-to-two-colors converter provides, pinned to pure black and white as the two output colors.

How Black and White Stamp Creator Works

For every pixel, luminance is calculated as `0.299*red + 0.587*green + 0.114*blue`, matching how human vision perceives brightness.

Pixels at or above the threshold become pure white, and pixels below it become pure black; the threshold slider controls exactly where that cutoff sits.

When To Use Black and White Stamp Creator

Use it when you want a stamp graphic that reads like true printed ink, with a crisp, high-contrast look rather than soft shading.

It's also useful for preparing a stamp for laser engraving, stencil cutting, or other processes that need strictly two-tone artwork.

Often used alongside Stamp to Grayscale Converter, Stamp to Single Color Converter and Rubber Stamp to Digital Stamp Converter.

Features

Advantages

Runs entirely client-side; the uploaded stamp is never sent to a server.
Produces a crisp, high-contrast result that mimics real stamped ink.
The threshold is fully adjustable, so you can control exactly how much detail survives.

Limitations

This is not the same as a grayscale conversion; it deliberately discards all intermediate tones.
Very low-contrast source images can lose fine detail entirely at certain threshold settings.

Examples

Threshold a lightly-shaded scan

Input

A stamp scan with soft gray shading, default threshold 128

Output

A crisp black-and-white version with hard edges

The default threshold works well for typical scanner contrast levels.

Preserve fine detail in a faint stamp

Input

A faint, low-contrast stamp photo, threshold 90

Output

A black-and-white version that keeps more of the faint marks as black

Lowering the threshold classifies more borderline pixels as black instead of white.

Best Practices & Notes

Best Practices

Try a few threshold values and compare the live preview, since the right cutoff depends heavily on the source image's contrast.
Scan or photograph the stamp with good, even lighting first for the cleanest threshold result.

Developer Notes

The luminance-threshold math lives in the shared png-to-two-colors-converter lib function; this tool's lib file thinly wraps convertPngToBlackAndWhite, which itself pins black and white as the two output colors, rather than re-deriving the threshold logic.

Black and White Stamp Creator Use Cases

Preparing a stamp graphic for laser engraving or stencil cutting
Creating a high-contrast, ink-like version of a photographed stamp
Reducing a scanned stamp's file size by simplifying it to two colors

Common Mistakes

Expecting smooth gradients to survive the conversion — thresholding always produces hard edges, never soft ones.
Using a threshold that's too extreme for the source image's actual brightness range, losing most detail to one color.

Tips

If you need multiple shades preserved instead of just two, use the stamp-to-grayscale converter instead.
Combine with the stamp color changer afterward if you want the 'black' ink recolored to something else.

Black and White Stamp Creator