Sharpening makes an image look clearer by increasing contrast at the edges where different colors or brightness levels meet. It doesn't add new details - it enhances the contrast that already exists, making the image appear more defined to the human eye.
How Sharpening Works
The tool uses an unsharp mask algorithm. It identifies edges (places where pixel values change rapidly) and increases the contrast at those boundaries. Light side becomes slightly lighter, dark side becomes slightly darker. This creates an illusion of greater sharpness that works well for most images when applied at modest levels (10-30% intensity).
When to Sharpen
- Slightly soft photos - Fix mild focus issues or camera shake in otherwise good shots.
- Product images - Bring out fabric textures, metal finishes, and fine details.
- Screenshots - Make text and UI elements more legible when sharing screen captures.
- Before printing - Compensate for the slight softening that happens during the printing process.
What Sharpening Can't Do
Sharpening can't fix heavily blurry or out-of-focus photos. It can't invent detail that was never captured. A very blurry image will still look blurry after sharpening - just with added edge halos. For truly blurry photos, you're better off retaking the shot.
Tips for Natural Results
- Start with 10-20% intensity and increase gradually
- Watch for noise in dark areas - high sharpening amplifies grain
- Sharpen should be the final step after resizing and cropping