Sharpening is one of those features that sounds great in theory. Blurry photo? Sharpen it! Soft image? Sharpen it! But the reality is more nuanced, and over-sharpening is far more common than under-sharpening.
What Sharpening Actually Does
Sharpening doesn't add detail. I want to be clear about that. It doesn't recover information that isn't there. What it does is increase the contrast along edges — making the boundary between light and dark areas more pronounced.
This creates an illusion of more detail. A slightly soft photo can look crisper. But push it too far and you get halos around edges, crunchy textures, and amplified noise. That "over-sharpened" look is immediately recognizable and looks terrible.
When Sharpening Helps
After resizing down. When you shrink an image, some sharpness is lost in the resampling process. A light sharpen (amount 50-80%, radius 0.5-1.0) restores the perceived crispness. This is probably the most legitimate use of sharpening.
Scanned documents. Scans of printed text are often slightly soft. Gentle sharpening makes text more readable.
Slightly out-of-focus photos. Emphasis on "slightly." A photo that's just a tiny bit soft can benefit from careful sharpening. A photo that's significantly out of focus cannot be saved by sharpening — it'll just look bad in a different way.
When Sharpening Hurts
Portraits. Sharpening accentuates skin texture, pores, wrinkles, and blemishes. Every skin imperfection becomes more visible. Portrait photographers typically apply a slight blur to skin, not sharpening.
Noisy images. Sharpening amplifies noise. If your photo has visible grain or digital noise (common in low-light photos), sharpening makes it look much worse. Denoise first, then consider very gentle sharpening.
Already-sharp images. If your photo is well-focused and shot on a good lens, it doesn't need sharpening. Adding it anyway creates those telltale halos and crunchy artifacts.
My Recommended Settings
For the typical "resize for web and sharpen" workflow:
- Amount: 60-80% (never above 120%)
- Radius: 0.5-1.0 pixels (larger radius = more aggressive)
- Threshold: 2-4 levels (prevents sharpening of smooth areas)
For scanned documents:
- Amount: 100-150%
- Radius: 1.0-1.5 pixels
- Threshold: 0-2 levels
Sharpen your images with precise control
Adjust amount, radius, and threshold. Preview the result before downloading.
Try Sharpen (Photo Editor)The Over-Sharpening Epidemic
I see over-sharpened images everywhere. Real estate listing photos with halos around every roofline. Product photos where the texture looks crunchy. Landscape photos where the trees look like they're glowing.
The test I use: zoom to 100% (actual pixels) and look at edges. If you can see a bright line along any edge that isn't in the original scene, you've over-sharpened. Back off until that halo disappears.
Better to under-sharpen than over-sharpen. A slightly soft image looks natural. An over-sharpened image looks processed. And once you've exported an over-sharpened JPEG, you can't undo it.