Quick Photography Tips

When used well, the addition of noise to an image with Photoshop can be very effective. Unfortunately, if you apply the Add Noise filter directly to your image layer then there is no easy way to go back and change the amount of noise or remove it completely later on without undoing all the edits you’ve made since. This tip will show you how to add noise to your images that can be adjusted or removed at any point later on.

We’ll start with this slightly creepy image of a doll’s face by Stewart…

It’s already a bit noisy due to being shot at ISO 400 but let’s add some more noise to it…

The first step is to create a new layer and fill it with 50% gray using the paint bucket. 50% gray is, as its name suggests, half way between black and white so the RGB sliders are all set to 128. The useful thing about a 50% gray layer is that a number of Photoshop’s layer blending modes treat it as tranparent. We can then add pixels to that layer that are a colour other than 50% gray and only those pixels will affect the look of out image.

The blend modes that treat 50% gray as transparent are Overlay, Soft Light, Hard Light, Vivid Light, Linear Light and Pin Light.

Once we’ve created our 50% layer above our image, we want to change its blend mode to one of those named above. Soft Light will give you a more subdued noise effect or Overlay will give you higher contrast noise.

You’ll notice that if you now turn on and off the visibility of the gray layer what you see doesn’t change because the 50% layer is just letting all the layer below show through. However, we can now apply our noise to the gray layer and add noise to our image without affecting the image layer itself. Select the gray layer and go to Filter -> Noise -> Add Noise. Choose whether you want your noise to be monochromatic or not, Gaussian or Uniform and then adjust the noise level until you get the look you are going for. Remember you can also reduce the opacity of the noise layer itself to vary the effect.

Here’s the resulting image with Soft Light blend mode…

…and with the same noise blended with the Overlay mode…