Binarize Images Online Convert images to pure black and white using adjustable threshold.

What Is Image Threshold?

Converts images to pure black and white. Pixels brighter than the threshold become white (255), darker become black (0).

Why Use Image Threshold?

• Adjustable threshold
• Clean binary output
• Useful for OCR preprocessing
• Fast per-pixel operation

Common Use Cases

Document Cleanup

Clean scanned documents.

Stencil Creation

Generate black-and-white stencils.

Logo Extraction

Isolate logos from backgrounds.

Shadow Art

Create silhouette art from photos.

Technical Guide

Luminance = R*0.299 + G*0.587 + B*0.114. If luminance >= threshold: 255, else 0.

Tips & Best Practices

• 1
  Start at 128 and adjust
• 2
  Lower = more white
• 3
  Higher = more black
• 4
  160-200 for text extraction

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Frequently Asked Questions

Q Same as grayscale?

No — grayscale has 256 shades; threshold has only black and white.

Q Right threshold?

Start at 128. For documents try 160-200.

Q What is luminance?

R*0.299+G*0.587+B*0.114, matching human brightness perception.

Q Per-channel threshold?

This uses combined luminance.

About This Tool

Image Threshold is a free online tool by FreeToolkit.ai. All processing happens directly in your browser — your data never leaves your device. No registration or installation required.