How do I threshold an image to black and white online?

Upload PNG, JPEG, WebP, or GIF. Move the threshold slider (0–255), review the two-tone preview, then download PNG. Processing runs in your browser.

Can I use this as a black and white filter?

Yes. This page is a hard black and white filter based on thresholding. If you want to make an image black and white with no gray levels, threshold is the right option.

What does the threshold value control?

Each pixel’s luminance is compared to the threshold. Values at or above the cutoff become white (255); values below become black (0). Mid settings near 128 split average photos roughly in half.

Is threshold the same as grayscale conversion?

No. Grayscale on /grayscale-image keeps many gray levels. Threshold produces a two-color black-and-white image with no mid-tones—useful for silhouettes, stamps, and high-contrast art.

How is this different from clip image?

Clip image thresholds each RGB channel separately. This tool uses one luminance cutoff so the result is true black and white based on perceived brightness.

Does threshold affect transparency?

Alpha on PNG uploads is preserved. Only RGB channels are forced to black or white.

Are files uploaded to a server?

No. Canvas processing stays on your device.

What is the maximum file size?

15 MB with a longest edge of 8192 px.

Input image

Threshold black and white online

Drop or click to upload PNG, JPEG, WebP, or GIF

Maximum file size: 15 MB

Image with threshold effect

Upload an image and move the threshold slider below—the preview updates automatically.

Threshold options

Pixels with luminance at or above the threshold become white; darker pixels become black. Lower values keep more of the image white; higher values keep more black.

Threshold

Threshold image black and white filter

Use a threshold filter to make an image black and white. Set the cutoff, preview the two-tone result, and download PNG in your browser.

What is a threshold effect?

A threshold effect converts a photo to black and white by comparing each pixel’s luminance to a cutoff value. Lighter areas become white and darker areas become black, with no gray mid-tones. In practical terms, this is a threshold filter you can use to make image black and white for silhouettes, masks, and high-contrast graphics. Move the slider to control how much of the image stays white versus black, then preview and download PNG directly in your browser.

Threshold controls

One slider threshold filter for two-tone black and white conversion.

Threshold 0–255: Pick the luminance cutoff that separates white and black regions.
Luminance-based: Uses ITU-R BT.601 weights so the split matches how eyes read brightness.
Live preview: Input and output panels update as you move the slider.
Pure black and white: Output pixels are only #000000 or #FFFFFF on RGB channels for a true black white filter look.
PNG download: Save as threshold-image.png.
Client-side only: No account and no server upload.

How to threshold an image

Steps to make image black and white with a threshold filter.

Upload your photo: Drop or click in the input panel (15 MB max).
Adjust threshold: Start near 128, then sweep lower for more white or higher for more black.
Download PNG: Save when edges and silhouettes look correct for your layout.

Tips for threshold black and white

Get cleaner two-tone black and white filter results.

Boost contrast first: If the preview looks muddy, try /change-image-contrast before thresholding.
Watch fine lines: Very thin strokes may disappear—lower threshold slightly to keep them white.
Start at 128: Middle gray cutoff is a sensible default for evenly lit photos.
Keep the color original: Threshold is destructive—save your source file before exporting.
Use PNG for logos: Transparency is preserved on uploads with alpha.
Avoid heavy JPEG noise: Compression artifacts can speckle the output—prefer PNG sources when possible.

When to use image threshold

Typical uses for two-tone black and white images.

Silhouettes and stamps: Isolate subjects as high-contrast shapes for logos or rubber-stamp mockups.
Scan cleanup: Binarize faint pencil or ink lines before tracing or OCR prep.
Stencil art: Find a cutoff that keeps cut lines closed before laser or screen printing.
QR and barcode prep: Push noisy scans toward clean black modules on white backgrounds.
Poster and zine graphics: Get punk or photocopy aesthetics with a hard threshold look.
Potrace and vector handoff: Pair with /imagetracer after thresholding high-contrast line art.

Why use this threshold tool

Benefits of browser-based black and white thresholding.

Instant feedback: Scrub the slider instead of guessing a level in desktop curves.
True 1-bit look: Not gradual grayscale—only black or white pixels on RGB.
Private: Files never leave your browser.
Free: Unlimited previews and downloads.
Complements grayscale: Use /grayscale-image when you need smooth tonal steps instead.
No install: Works on desktop and mobile with Canvas 2D.

Technical details

How threshold is applied.

Algorithm: Luminance = 0.299R + 0.587G + 0.114B; output 255 if luminance ≥ threshold else 0.
Output: Strict two-level RGB; not error-diffusion or adaptive threshold.
Rendering: Canvas 2D getImageData / putImageData; alpha unchanged.
Input limits: 15 MB; longest edge 8192 px.
Related tools: /grayscale-image for multi-tone gray; /clip-image for per-channel clipping.
Browser support: Chromium, Firefox, Safari with Canvas 2D.

Frequently Asked Questions

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