Sharpen Images Online Sharpen images with adjustable intensity using unsharp mask convolution.

What Is Image Sharpen?

Image sharpening enhances edges and fine details by applying a convolution kernel that amplifies differences between neighboring pixels. The sharpen kernel increases contrast at edges making the image appear crisper. This tool uses a 3x3 sharpening kernel with adjustable intensity, blending between the original and sharpened result.

Why Use Image Sharpen?

• Adjustable sharpening intensity from subtle to aggressive
• 3x3 convolution kernel for precise edge enhancement
• Blend control between original and sharpened image
• Client-side Canvas API processing for instant results

Common Use Cases

Fix Soft Photos

Rescue slightly out-of-focus or soft images by enhancing edges.

Print Preparation

Sharpen images before printing to ensure crisp output.

Detail Enhancement

Bring out fine textures in macro photography or product shots.

Post-Resize Sharpening

Apply sharpening after resizing to compensate for interpolation softness.

Technical Guide

Sharpening uses a 3x3 convolution kernel: [0, -t, 0, -t, 1+4t, -t, 0, -t, 0] where t is the sharpening strength. As t increases, the center weight increases while neighbor weights become more negative, amplifying edge differences.

Tips & Best Practices

• 1
  Use moderate sharpening (20-40%) for natural-looking results
• 2
  Over-sharpening creates visible halos around edges
• 3
  Sharpen as the last step in your editing workflow
• 4
  Noisy images should be denoised before sharpening

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Frequently Asked Questions

Q Can sharpening fix a very blurry image?

Sharpening helps slightly soft images but cannot recover severely blurred ones.

Q What causes halo artifacts?

Over-sharpening creates bright/dark halos around high-contrast edges.

Q Should I sharpen before or after resizing?

After resizing — resizing introduces softness that sharpening can correct.

Q Does sharpening add noise?

Yes, sharpening amplifies all pixel differences including noise.

About This Tool

Image Sharpen 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.