What is image noise?

Noise is the fine random speckle in photos taken in low light, and grain is its film counterpart. Adding it on purpose sounds odd, but it helps: grain gives digital photos the texture of film, breaks up the visible bands in smooth gradients like skies, and makes retouched or generated areas blend in with the rest of a photo. Designers also add a little noise to flat colors for a subtle printed look.

Tool description

Open an image and set the amount. Grain size turns single pixel speckles into larger, softer grains, and Monochrome switches between gray film grain and colored noise like a digital camera's. The noise is the same every time for the same image, so it doesn't flicker while you change the settings, and the download keeps the image's full size.

Features

  • Adjustable amount and grain size
  • Monochrome film grain or colored noise
  • Before and after comparison
  • Runs in your browser, so the image never leaves your device

How it works

Every pixel gets a random brightness change from a bell curve, centered on zero so the image keeps its overall brightness. The random numbers come from a seeded generator, which is why they repeat exactly. For grains bigger than a pixel, the noise is blurred and then scaled back up to the same strength. In monochrome mode one value goes to red, green, and blue alike, so only brightness changes; otherwise each channel gets its own noise. Large photos are previewed on a smaller copy, which shows the noise the full size result has when you view it at that size.

Tips

  • For a film look, keep Monochrome on and use a small amount with a small grain size.
  • To hide banding in a gradient, a little noise is enough. Save as PNG or a high quality JPG, since strong compression smooths the noise away again.
  • Noise makes files bigger, because JPG and WebP compress it poorly.