Film grain adder
Choose a photo and add grain that looks like film: set its strength and size, choose grey or coloured noise, and darken the corners with a vignette. The grain pattern is repeatable, so the saved file looks like the preview.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Choose or drop a photo.
- Set the Grain amount and Grain size.
- Choose Mono or Coloured grain.
- Add a Vignette if you want darker corners, then download.
How it works
The grain is a noise value per block of pixels, between about −64 and +64 levels at 100 %, added to the colour channels and kept between 0 and 255. After that the vignette multiplies each pixel by 1 − strength × d², where d is the distance from the centre divided by the distance to a corner.
Example
With a vignette of 50 %, a corner pixel of brightness 200 becomes 100, while the centre pixel stays 200. With the grain amount at 0 the picture is not changed at all.
Tips
- Grain looks best on pictures that are not too sharp; a size of 2 to 3 pixels is natural on photos of a few thousand pixels.
- A light vignette (15–30 %) is usually enough; strong values look like a tunnel.
Frequently asked questions
How is the grain made?
Each block of pixels gets a random offset, added to the colour channels. The offsets are the average of three random numbers, which makes small changes common and big ones rare, like real grain. The generator is seeded, so the same settings always give the same pattern.
What is the difference between mono and coloured grain?
Mono adds the same offset to red, green and blue, so only brightness flickers, as in black-and-white film. Coloured adds a separate offset to each channel, which gives the speckled colour noise of high-speed colour film or a high ISO sensor.
What does the vignette do?
It darkens the picture towards the corners. The factor is 1 minus the strength times the squared distance from the centre (0 in the middle, 1 in the corners), so a strength of 50 % halves the corner brightness and leaves the centre unchanged.
Will the grain look the same on a big file?
The grain size is in pixels of the saved file and is scaled in the preview, so the look matches. Very fine grain on a large photo is only seen at 100 % zoom.