OneTaskBy Tim King · Updated
Sharpen Blurry Photo Online
Unsharp Mask and Edge-Preserving Denoise to Fix Grainy, Soft Photos
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How the Image Sharpen And Denoise works
Use this to sharpen blurry photo online, with optional denoise. Drop in a photo that came out a little soft or a little grainy and tune two things: how much noise to smooth away and how much to sharpen what remains. The denoise step runs first so the sharpening does not amplify the grain, and a detail score tells you whether the result really has more edge contrast than the original. The picture never leaves your browser.
Sharpen blurry photo online: getting a good result
Sharpening and denoising pull in opposite directions, which is why doing them in the wrong order makes a photo worse. Noise is fine, high-frequency variation; sharpening boosts exactly that. So this tool smooths first and sharpens second, and lets you set each independently.
Denoise strength controls how aggressively pixel variation is smoothed. Smooth (keep edges) uses a bilateral filter: each pixel is averaged with its neighbours, but neighbours that differ a lot in colour are given little weight, so flat areas like sky and skin are cleaned while real edges stay crisp. It suits sensor grain from a high-ISO photo. Median (speckle) replaces each pixel with the median of its neighbourhood, which is the right choice for salt-and-pepper noise, dust from a scanned print or JPEG blocking, because isolated wrong pixels are simply voted out. Push either method too far and the image starts to look like a painting; twenty to forty is the usual range.
Sharpen amount is an unsharp mask, the same operation as in Photoshop and Lightroom. A blurred copy of the image is subtracted from the original to isolate the edges, and that difference is added back scaled by the amount. Sharpen radius sets how wide the blur is, which decides what counts as an edge: around one to two pixels for fine texture and web-sized images, larger for big prints or when you want to lift broad, soft shapes rather than fine detail. Amounts over about 120 percent tend to leave bright haloes along strong edges.
The detail score is the variance of the Laplacian, a standard measure of how much edge energy an image has. A higher number after processing means sharper; a much higher number with a low denoise setting usually means you have sharpened the noise. Images larger than 4000 pixels on the long side are scaled down before processing, and the result is saved as a PNG.
FAQ
Which order should I set the sliders?
Denoise first, until the grain is gone from flat areas but edges are still crisp, then add sharpening until the detail score rises without haloes. The tool always applies them in that order regardless of which slider you move first.
Why are there bright halos along edges?
Too much sharpen amount or too wide a radius. Drop the amount below about 120% and keep the radius at one to two pixels for web-sized images.
Can it fix a badly out-of-focus photo?
No. Unsharp masking boosts edge contrast that already exists; it cannot recover detail that was never captured. It rescues a slightly soft photo, not a missed focus.
Which denoise method for a scanned print?
Median. Dust and scratches are isolated wrong pixels, which the median filter removes outright, whereas the bilateral filter would soften them into smudges. Keep the radius small so the filter takes out specks without rounding off the edges of text.
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