Black and White Image Threshold guide
Turn a color image into pure black and white pixels with a controllable luminance cutoff, entirely in your browser.
What this tool does
The Black and White Image tool creates a two-tone image. It calculates perceptual luminance from each pixel’s red, green, and blue values, then compares that result with your selected threshold. Pixels at or above the threshold become white; pixels below it become black. Transparency is kept, so transparent areas in a PNG or WebP remain transparent.
This is thresholding, not ordinary grayscale conversion. A grayscale image can contain hundreds of shades between black and white, while this result contains only the two extremes in its visible RGB channels. Lower thresholds make more of the picture white. Higher thresholds require a brighter source pixel to produce white, so the result becomes darker.
The tool applies one threshold to the complete image. It does not trace objects, remove backgrounds intelligently, create vector paths, recognize text, or use adaptive thresholds for different regions. Photos with uneven lighting may need editing elsewhere before a single global cutoff produces a clean result.
How to use it
- Choose a JPG, PNG, or WebP file up to 25 MB.
- Move the threshold slider toward 0 for a lighter result or toward 255 for a darker result.
- Select Apply threshold to process the current setting.
- Download the new image and inspect fine edges at full size.
- Keep the source file in case you want to try another cutoff.
For scanned handwriting, start near the middle and increase the threshold until paper texture disappears without losing thin strokes. For silhouettes, try several values because hair and soft edges can change quickly.
Use the Grayscale Image Converter when intermediate shades should remain instead of becoming pure black or white.
Benefits
- Produces true two-tone RGB output instead of gray shades
- Uses luminance weighting rather than a simple channel average
- Preserves the source pixel dimensions and alpha channel
- Supports common JPG, PNG, and WebP input
- Enforces a decoded-pixel limit for browser stability
- Processes the file locally without an upload
Export and quality notes
The browser re-encodes the processed pixels. PNG is the best choice for sharp two-tone graphics, but a JPG source is exported as JPG and can show compression artifacts around hard edges. Embedded EXIF, color-profile, and text metadata may not be retained by canvas export. The original file is never overwritten.