Sharpen Image
Make slightly soft photos and scans crisper — and check the result at 100%.
Preview
Drag across the photo to move the divider. Arrow keys move it too. In 100% and 200% view, drag the photo (or use the arrow keys) to look around.
Sharpening
Sharpening makes slightly soft photos and scans crisper. It cannot fix motion blur or a missed focus, and it cannot add detail the camera never captured — judge the result in the 100% view.
Save
Edit several photos
Add more photos to give them all the same settings and download them together as a ZIP.
About the Sharpen Image
Open a photo or scan and sharpen it with an unsharp mask (amount, radius and threshold) or a large-radius high-pass clarity boost for flat, hazy pictures. An optional light noise reduction runs first, so grain from a phone camera is not sharpened along with the detail.
Sharpening is judged at the pixel level, so the preview opens at 100%: drag the divider to compare the original with the result, drag the photo to look around, or switch to 200%, side by side or Fit. Add several photos to give them all the same settings and download them as one ZIP. Everything runs on your device in a background thread — nothing is uploaded.
How to use it
- Choose, drop or paste a photo (several for a batch).
- Pick a starting point — Gentle for phone photos on the web, Print for large prints, Scan / text for documents — or set Amount, Radius and Threshold yourself.
- Look at the 100% view: edges should look crisper without white or dark outlines around them. Lower the radius or the amount if you see halos; raise the threshold if skin or sky gets grainy.
- Choose a format and select Download, or Download all as ZIP for a batch.
Examples
Gentle: amount 80%, radius 0.8 px, threshold 2
Crisper eyelashes and textures; smooth skin and sky are left alone
Resize first (for example to 1080 px wide), then sharpen — sharpening is best done at the final size.
Scan / text: amount 220%, radius 1.5 px, threshold 0
Letters with cleaner, darker edges that are easier to read and to OCR
High-pass clarity: strength 60%, radius 15 px
More separation between hills, trees and sky without crunchy fine detail
How unsharp masking works
Unsharp masking is a classic technique described in Gonzalez & Woods, Digital Image Processing (4th ed.): blur the image, subtract the blur from the original to get a "mask" of fine detail, and add that mask back, scaled by the amount:
g(x, y) = f(x, y) + k · [f(x, y) − blur(f)(x, y)]
Here the blur is a Gaussian whose standard deviation is the radius, k is the amount (100% = 1), and only differences larger than the threshold (in 0–255 brightness levels, with a soft transition) are boosted. The tool sharpens brightness only (BT.601 luma), so edges do not get coloured fringes.
High-pass clarity uses the high-pass layer 0.5 + (f − blur(f)) blended in overlay mode, the well-known high-pass sharpening technique. With a large radius it increases local contrast, and the overlay blend strengthens it most in the midtones, so highlights and shadows clip less.
Choosing the settings
- Radius: match it to the detail. 0.5–1 px for web-size photos, 1–2 px for large prints and scans. Halos (light or dark outlines) mean the radius or amount is too high.
- Amount: 50–150% for most photos. Scans and text can take 200% or more.
- Threshold: 2–6 levels keeps skin, sky and noise smooth while edges are sharpened. Use 0 for text and line art.
- Reduce noise first: use it for photos taken in low light, where sharpening would otherwise make the grain worse.
Sharpen last, at the final size
Resizing changes how much sharpening an image needs, and shrinking a photo makes it look sharper on its own. Crop and resize first (for example with the Image Resizer), then sharpen, and compress last with the Image Compressor — heavy JPEG compression after sharpening can bring out blocky artefacts.
Limitations
- Sharpening raises the contrast of edges that exist; it cannot undo motion blur, camera shake or a photo that is out of focus, and it cannot invent detail that was never captured. For small images that need more pixels, an upscaler is the right kind of tool.
- Strong settings create halos and make noise and JPEG artefacts more visible — check the 100% view before saving.
- The Fit view shows a scaled-down preview, which hides most of the effect; judge sharpening at 100% or 200%.
- Photos up to 50 megapixels. Very large photos can exceed the memory of some phones.
- Saving re-encodes the photo; JPEG and WebP at 90% quality are a good balance. Metadata such as EXIF is not copied.
Privacy
Everything happens in your browser. What you enter or open here is not uploaded or stored by MySmartCoPilot.
Frequently asked questions
Can this fix a blurry photo?
Only a little. It helps photos that are slightly soft — from a phone lens, a soft scan or resizing. It cannot fix motion blur or a photo where the camera focused on the wrong thing, because the detail is not in the file.
What is the difference between unsharp mask and high-pass clarity?
Both add back the difference between the photo and a blurred copy. Unsharp mask uses a small radius and targets fine edges; high-pass clarity uses a large radius and boosts the contrast of larger shapes, which makes flat or hazy photos look more defined.
Why do I see white or dark outlines around edges?
Those are halos from too much sharpening. Lower the amount or the radius. A radius of 0.5–1.5 px is enough for most photos.
Should I sharpen before or after resizing?
After. Resize to the final size first, then sharpen for that size. Sharpening a large photo and then shrinking it wastes most of the effect.
Can I sharpen many photos at once?
Yes. Add several photos; the settings apply to all of them. Select any photo in the list to preview it, then use Download all as ZIP.
Are my photos uploaded?
No. The photos are processed in your browser, in a background thread on your device. Nothing is sent to a server, and the tool works offline once the page has loaded.