# AI Image Sharpener: Fix Soft Renders Free in Your Browser URL: https://prexi.art/tools/ai-image-sharpener Type: tool Locale: en Published: 2026-10-20 Updated: 2026-10-24 --- > Load a soft render, tune amount, radius and threshold, and drag the split to compare. A free in-browser sharpener with a halo check. Nothing leaves your device. ## The AI Image Sharpener That Runs Free in Your Browser Load a soft render, push the sliders, drag the split. Your image never leaves your device, and the sharpened file is one click away. ## Image sharpener Load an image or use the soft sample. Pick a preset, tweak amount, radius and threshold, then drag the split to compare. Nothing is uploaded. *[Interactive widget — see the live page for the full experience]* ## Three sliders, one honest filter No black box. Here is exactly what happens to your pixels. ### Blur, subtract, add back The tool makes a blurred copy of your image, subtracts it from the original to isolate the edges, then adds those edges back, scaled by your amount. That is an unsharp mask, the oldest trick in the darkroom and still the one that works. ### Radius and threshold Radius sets how wide the blur is, so how thick the edges you boost. Threshold ignores differences smaller than your setting, which keeps skin, sky and soft gradients clean instead of grainy. ### A number you can check After every change the tool measures detail gain with a Laplacian variance, and counts clipped pixels. Gain tells you if anything changed. Clipping tells you if you pushed into halos. *When to use it* ## Soft is not the same as bad Most AI renders come out a touch soft. Flux at 1024 px, a Midjourney upscale, a Nano Banana Pro export you shrank for the web: the composition is right, the edges are mushy. A light unsharp mask is the fastest fix, and it costs nothing. Use the presets as a starting point, then trust your eyes at 100%. - AI render, slightly soft: amount 130%, radius 1.2 px. Good for fresh Flux and Midjourney outputs. - Everyday photo: amount 90%, radius 0.8 px. A clean, believable lift. - Upscaled or very soft: amount 160%, radius 2 px. Run this after a 2x or 4x enlarge. - Light touch for the web: amount 60%, radius 0.6 px. Survives JPEG compression. ## Sharpen in under a minute 1. **Load your image** — Pick a JPG, PNG or WebP file, or start from the built-in soft sample to see how the sliders behave. 2. **Pick a preset, then adjust** — Start with the preset closest to your image. Nudge amount first, radius second, threshold last. Drag the split to compare. 3. **Check the verdict, then download** — If the readout says clean, export at full size as PNG, JPEG or WebP. If it warns about halos, back off the amount. Steal this workflow. ## Common questions ### Is this actually AI? No, and we are not going to pretend. It is a classic unsharp mask, the same maths behind the sharpen filter in every photo editor. It fixes the soft look of most Flux, Midjourney and Nano Banana Pro outputs. It does not invent detail. For that you need a generative upscaler like Magnific, Krea or Topaz. ### Is it free, and does my image get uploaded? Free, no signup, no email gate. Your image never leaves your browser. The sharpening runs on your own device, so there is nothing to upload and nothing stored. ### What do amount, radius and threshold actually do? Amount is how hard the edges get pushed. Radius is how wide the edge contrast spreads, in pixels at full size. Threshold skips tiny differences so skin, sky and gradients stay smooth instead of turning into noise. ### Why do I get white halos around edges? You pushed amount or radius too far. The filter overshoots on both sides of an edge, and past a point that overshoot reads as a glow. Watch the clipped pixels figure under the preview: above 3% you are in halo territory. ### What is the detail gain number? It compares the variance of a Laplacian edge filter before and after, a standard quick measure of sharpness. A gain of x1.5 to x3 usually looks natural. Much above x8 and you are sharpening noise. ### Should I sharpen before or after upscaling? After. Upscale first, then sharpen once at the final size. Sharpening a small image and then enlarging it magnifies the halos along with everything else. ### Why does sharpening brightness only matter? Sharpening each color channel separately can leave colored fringes on high contrast edges. Working on brightness alone keeps the colors untouched, which is why it is the default. ### Will it fix a badly blurred or out of focus image? No. Unsharp masking restores crispness to a slightly soft image. Real motion blur or missed focus has lost the information, and only a generative model can guess it back. ## Steal this prompt, then sharpen what it makes. prexi.art tracks what actually works across Midjourney, Flux, Nano Banana and SD3.5. Tested, not guessed. *Call to action: Explore more prompts on prexi.art* ## FAQ ### Is this actually AI? No, and we are not going to pretend. It is a classic unsharp mask, the same maths behind the sharpen filter in every photo editor. It fixes the soft look of most Flux, Midjourney and Nano Banana Pro outputs. It does not invent detail. For that you need a generative upscaler like Magnific, Krea or Topaz. ### Is it free, and does my image get uploaded? Free, no signup, no email gate. Your image never leaves your browser. The sharpening runs on your own device, so there is nothing to upload and nothing stored. ### What do amount, radius and threshold actually do? Amount is how hard the edges get pushed. Radius is how wide the edge contrast spreads, in pixels at full size. Threshold skips tiny differences so skin, sky and gradients stay smooth instead of turning into noise. ### Why do I get white halos around edges? You pushed amount or radius too far. The filter overshoots on both sides of an edge, and past a point that overshoot reads as a glow. Watch the clipped pixels figure under the preview: above 3% you are in halo territory. ### What is the detail gain number? It compares the variance of a Laplacian edge filter before and after, a standard quick measure of sharpness. A gain of x1.5 to x3 usually looks natural. Much above x8 and you are sharpening noise. ### Should I sharpen before or after upscaling? After. Upscale first, then sharpen once at the final size. Sharpening a small image and then enlarging it magnifies the halos along with everything else. ### Why does sharpening brightness only matter? Sharpening each color channel separately can leave colored fringes on high contrast edges. Working on brightness alone keeps the colors untouched, which is why it is the default. ### Will it fix a badly blurred or out of focus image? No. Unsharp masking restores crispness to a slightly soft image. Real motion blur or missed focus has lost the information, and only a generative model can guess it back.