Free Online Image Denoiser — Remove Noise & Grain from Photos
Easily reduce digital noise and grain from your photos with our free online denoising tool. Powered by a median filter algorithm, it removes random noise pixels while preserving edge sharpness and image detail — unlike simple blur filters that soften everything. Perfect for fixing low-light photos, reducing sensor noise from high ISO settings, cleaning up scanned images, or removing compression artifacts. All processing happens in your browser for complete privacy — your images never leave your device.
Upload the image you want to denoise by dragging it onto the upload area or clicking to browse your files.
Drag the denoise radius slider to control the strength. Radius 1-2 for subtle, 3-4 for moderate, 5-6 for strong, 7-8 for aggressive denoising. The preview updates instantly.
Download your denoised image in its original format when you're satisfied with the result.
Tips for Better Denoising Results
- For subtle noise reduction on slightly grainy photos, use radius 1-2. This preserves fine details like skin texture and hair while smoothing minor noise.
- For low-light or high-ISO photos with significant noise, use radius 3-4 for a good balance between noise removal and detail preservation.
- For extremely noisy images, use radius 6-8 for aggressive denoising. Be aware that very large radii will significantly soften fine details. When in doubt, start with a moderate radius and increase gradually.
Frequently Asked Questions — Image Denoising
Is the image denoising tool really free?
Yes, completely free. No registration, no hidden charges, no watermarks, and no file size limits. All processing happens locally in your browser — your images never leave your device.
How does the median filter denoising algorithm work?
The median filter works by examining each pixel's neighborhood (defined by the radius slider) and replacing the pixel with the median value of all pixels in that neighborhood. For each color channel (R, G, B), the values are collected and sorted, and the middle value is selected as the output. This is remarkably effective at removing random noise pixels while preserving sharp edges — unlike mean/average filters that blur everything equally.
What does the denoise radius control do?
The radius slider (0-8) controls the size of the neighborhood examined for each pixel. Radius 1 = 3×3 (9px), radius 2 = 5×5 (25px), radius 3 = 7×7 (49px), radius 5 = 11×11 (121px), radius 8 = 17×17 (289px). A larger radius provides stronger noise reduction but progressively softens fine image details. For most photos, radius 2-4 offers the best balance.
What image formats are supported?
JPG, PNG, WebP, BMP, AVIF, GIF, TIFF, SVG, HEIC and more. The denoised result is saved in your original upload format, preserving compatibility.
What is the difference between median filter denoising and blurring?
This is an important distinction! A blur (mean) filter averages all pixels in the neighborhood equally, which reduces noise but also blurs edges and fine details. A median filter replaces each pixel with the median value of its neighbors, which effectively removes outlier noise pixels while keeping edges relatively sharp. This makes median filtering the preferred choice for noise reduction in photography.
Can denoising fix blurry or out-of-focus photos?
No. Denoising removes random pixel noise (grain), not blur. If your photo is blurry or out of focus, the blur/sharpening tools elsewhere on ImageMatrix are more appropriate. Denoising specifically targets the random brightness variations that create a grainy or noisy appearance.
How large of an image can I process?
Our tool handles images up to 50 megapixels (50,000,000 pixels total). If your image exceeds this limit, you'll see a warning and can try a smaller version or reduce the resolution before denoising.