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Threshold

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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.

  1. Threshold 0–255: Pick the luminance cutoff that separates white and black regions.

  2. Luminance-based: Uses ITU-R BT.601 weights so the split matches how eyes read brightness.

  3. Live preview: Input and output panels update as you move the slider.

  4. Pure black and white: Output pixels are only #000000 or #FFFFFF on RGB channels for a true black white filter look.

  5. PNG download: Save as threshold-image.png.

  6. 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.

  1. Upload your photo

    Drop or click in the input panel (15 MB max).

  2. Adjust threshold

    Start near 128, then sweep lower for more white or higher for more black.

  3. 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.
  • 01

    Boost contrast first

    If the preview looks muddy, try /change-image-contrast before thresholding.

  • 02

    Watch fine lines

    Very thin strokes may disappear—lower threshold slightly to keep them white.

  • 03

    Start at 128

    Middle gray cutoff is a sensible default for evenly lit photos.

  • 04

    Keep the color original

    Threshold is destructive—save your source file before exporting.

  • 05

    Use PNG for logos

    Transparency is preserved on uploads with alpha.

  • 06

    Avoid heavy JPEG noise

    Compression artifacts can speckle the output—prefer PNG sources when possible.

Image Threshold Tools Compared — Which One Fits Your Workflow

How this free threshold image tool stacks up against other popular online options for converting images to black and white.

  1. ImageOnline.co

    Image threshold/binarization tool with adjustable threshold level. Clean interface but JPEG-only output with watermark prompt.

  2. PineTools.com

    Threshold adjustment with upload-apply-download. No real-time slider preview.

  3. OnlinePNGTools.com

    PNG threshold tool. Only accepts PNG input—not suitable for JPG/WebP users.

  4. Adobe Express

    Threshold not available as standalone; must use full photo editor with manual adjustments.

  5. Threshold Image

    Adjustable threshold level slider (0-255). Converts image to pure black and white (1-bit). Real-time preview. Side-by-side comparison.

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.

Sources & References

Authoritative references on image thresholding, Canvas API pixel manipulation, and the PNG format.
  • “Thresholding is the simplest method of image segmentation.”
    — Wikipedia — Thresholding (image processing)

    Thresholding (image processing): This tool applies a global luminance threshold to convert photos to pure black and white. Pixels above the cutoff become white; pixels below become black, with no gray mid-tones. en.wikipedia.org/wiki/Thresholding_(image_processing)

  • “The Canvas API provides a means for drawing graphics via JavaScript and the HTML canvas element.”
    — MDN Web Docs — Canvas API

    Canvas API (pixel manipulation): Canvas 2D getImageData/putImageData computes per-pixel luminance using BT.601 weights and compares it to the threshold slider value for real-time binary output. developer.mozilla.org/en-US/docs/Web/API/Canvas_API

  • “PNG supports lossless data compression, making it useful for storing graphics that need to be edited repeatedly without losing quality.”
    — W3C — PNG Specification (overview)

    PNG image format: Downloading the threshold result as PNG preserves the sharp black-and-white edges without compression artifacts, ideal for silhouettes and stencil art. w3.org/TR/PNG/

  • “A binary image is one that consists of pixels that can have one of exactly two colors, usually black and white.”
    — Wikipedia — Binary image

    Binary images in digital processing: Thresholding converts a grayscale image into a binary black-and-white image by setting a cutoff value — pixels above the threshold become white, below become black. en.wikipedia.org/wiki/Binary_image

Frequently Asked Questions

Quick answers about this tool—open a question to read more.