Skip to main content
PulsarKit

Sharpen Image

Apply a real unsharp mask with amount, radius and a noise threshold, and preview the result before you download it.

Drop your files here

.jpg, .jpeg, .png, .webp, .avif, .bmp · up to 100 MB

How to Sharpen Image

  1. 1

    Drop your image

    Add a JPG, PNG, WebP, AVIF or BMP file, or up to twenty at once with the same settings.

  2. 2

    Move the amount slider

    Start from the Photo preset and adjust amount, radius and threshold. The before/after view updates live.

  3. 3

    Download the sharpened file

    Save one file directly, or grab a ZIP when you processed a batch.

What unsharp masking actually does

Despite the name, unsharp masking does not add detail. It exaggerates the edges that are already in the photo. The tool blurs a copy of the image, subtracts that blurred copy from the original to isolate the edges, then adds a scaled version of that difference back on top. The result is a picture where boundaries look crisper even though no new information was created. This is the same technique darkroom printers used decades before software existed, done here with a separable Gaussian blur running in linear light so contrast edges do not pick up dirty color fringes.

Reading amount, radius and threshold

Amount controls how strongly the edge difference is added back. Higher values mean more visible contrast at boundaries, and pushing it too far produces bright or dark halos next to strong edges. Radius sets how wide an edge has to be before it counts as one: a small radius sharpens fine detail like eyelashes or text, while a larger radius emphasizes broader shapes. Threshold protects flat areas: any difference smaller than the threshold is treated as sensor noise and left alone, which is exactly what keeps a smooth sky or a scanned page background from turning speckled. The Photo, Text and Web presets are just sensible starting combinations of these three numbers. Moving any slider afterward switches the preset to Custom automatically.

Your file never leaves your device

The blur, the mask and the final blend all run inside your browser tab using plain pixel math. There is no upload, no server-side queue, and no copy of your photo kept anywhere. Close the tab and the image and every intermediate buffer are gone from memory immediately.

Frequently asked questions

What does the radius slider control?

Radius sets the size of the blur used to find edges, in pixels. A small radius (0.5–1) sharpens fine texture like skin pores, hair or small text. A larger radius (3–5) targets bigger shapes and works better on scans or images meant to be viewed from a distance.

Why is there a noise threshold?

Without it, sharpening amplifies sensor grain and JPEG artifacts in flat areas, such as a blue sky or a plain wall, just as much as real edges. Threshold ignores any difference smaller than its value, so smooth regions stay smooth while genuine edges still get sharpened.

Why do I see light or dark outlines near edges?

That is called haloing, and it is a normal side effect of unsharp masking pushed too far. Lower the amount slider, or raise the threshold slightly, until the edge looks crisp rather than outlined.

Will this fix a badly blurred or out-of-focus photo?

No. Unsharp masking only strengthens contrast at edges that already exist. It cannot recover detail lost to heavy motion blur or missed focus.

What do the Photo, Text and Web presets change?

Photo (80/1.0/4) is a balanced default for regular pictures. Text (150/0.6/0) uses a tight radius and no threshold to make scanned or photographed text crisper. Web (60/0.8/8) is gentler and raises the threshold to avoid amplifying compression noise on images bound for a web page.

Does sharpening make the file bigger?

Usually only slightly. Sharpening adds contrast detail, which can make JPEG or WebP compression slightly less efficient, but the change is typically a few percent, not a dramatic size jump.

How many images can I sharpen at once?

Up to twenty files in one batch, all with the same amount, radius and threshold. Results come back as a single ZIP archive.

Why did my BMP come back as a PNG?

The browser's Canvas API can decode BMP but cannot encode it, so the sharpened result is saved as a lossless PNG instead. AVIF inputs are saved as WebP for the same reason. JPEG, PNG and WebP inputs keep their original format.

Related tools

Compress ImageShrink JPG, PNG, WebP, AVIF and GIF files in your browser: pick a level that keeps the resolution, or, for all but GIF, a target size in KB or MB.Resize ImageChange the pixel dimensions of a photo by exact size, percentage or a ready preset, without leaving your browser.Photo EditorLayers, text, shapes, a brush and colour adjustments on one canvas. Everything runs in this tab and nothing is uploaded.