Photoshop Tutorial: Contrast Masking

Tame contrast and even out the dynamic range of your photos with this simple technique.

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What you need

To follow through with this tutorial you need at least Photoshop CS. More recent versions of Photoshop may appear a little different (mostly the interface has added features) as this tutorial is originally from 2006, but the techniques here are sound and work quite well across all versions since its publish.

To follow along with this tutorial you will need to download this image: Contrast-Masking.jpg (right-click and choose: Save As).

What is Contrast Masking and when should you use it?

Contrast Masking has two purposes. Recently it has gained popularity for faking High Dynamic Range images (those that have an unusually high range of light and contrast compared to a standard image). If cranked up all the way, you can exaggerate the details in an image, making it surreal.

Traditionally, Contrast Masking comes from a darkroom technique which was used to control and tame a high contrast image and improve the mid-range details. It works great on images that have distinct areas that are light and dark and a bit too much contrast. Contrast Masking will lighten the dark areas and darken the light areas, bringing the range of brightness more towards the middle, rather than the ends. And it does this without overly flattening the contrast of the image: it still retains its “‘pop.”

How to use Contrast Masking:

Open the image (Contrast-Masking.jpg) and make sure the Layers Palette is visible. Windows shortcut keys are used here. If you use a Mac, just replace the Ctrl key with the Command key.

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  • Open the photo.

This is a decent image with good exposure and color. But I think it is too contrasty.

  • Select the Background Layer (1) and press Ctrl-J to make a duplicate of it.
  • Name this new layer “Contrast Mask” (2)

The Background Layer will stay as is and will contain your original image so you don’t destroy it, and can return to it at any time. This is a good practice for all Photoshop workflows.

Contrast masking original Your Layers Palette:
Duplicate layer and rename
  • Set the Blending Mode for the Contrast Boost layer to Overlay (3) and
  • then change the Opacity of that layer to 75% (4).

80% is not a definite number for all types of photos. I generally find 100% to always be too strong, and 80% is always a good place to start.

Overlay layer overlay layer
Now we need to remove all the color from the Contrast Mask and turn it into a negative.

  • With the Contrast Boost layer selected, in the Image menu, choose Adjustments and then Desaturate (5).

This will remove all the color from the layer, but you won’t see that effect completely in the image, since this layer is set to Overlay blending.

  • Return to the Adjustments menu and this time choose Invert (6).

This will turn that layer into a negative image.

Contrast-Masking-result-step5-6 Image>Adjustments menu:
Adjustments menu
Now the image contrast is flat. The mask made every dark pixel lighter and every light pixel darker. Masking pixels precisely creates too much detail and reduces clarity. We want to blur the mask so it masks wider zones than just pixels.

  • In the Filter menu, choose Blur, and then Gaussian Blur (7).
  • Change the Radius to 30 pixels (8).

30 pixel is not a definite number. See the grey preview in the blur window? Notice how the sharp image turned into soft blotches of black and grey. This level of blur masks out zones, rather than precise pixels and lines. This makes the mask really smooth across the whole image. This number depends on your tastes and the resolution of the image. Higher resolution images may require a higher number.

Contrast-mask-result-step7-8 Gaussian Blur
The Contrast Mask has been made and it has tamed the contrast of the image, perhaps a bit too much. Let’s tone it down.

  • Change the Opacity of the Contrast Mask layer to your liking. I went with an Opacity of 50% (9).

Decreasing the Opacity will lessen the effect of the mask. Increasing the Opacity will make the mask stronger. Find a good balance that works right for your image.

Contrast mask final 50% opacity

Final Results

To directly compare the before and after, toggle the Contrast Mask layer on and off by clicking the eye icon next to the layer. In the final image you’ll notice that overall detail is increased, shadows are reduced and more balanced, and the overall brightness is better without blowing out the highlights of the waterfall. Contrast Masking can be a powerful tool for balancing the exposure across an image without destroying details. It’s best that you experiment on multiple types of images, and multiple settings, in order to find out what works best in what situation.

Contrast masking original

Original image

Contrast mask final

With Contrast Mask applied

What's Next

More Photoshop tutorials can be found in our Articles section.

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