Features in detail > Key > Spill suppression

Even a perfectly composited image can still suffer from color spill. This is when the green or blue of the screen is reflected on the subject. While this is often difficult to see in the original image, once it has been composited it becomes extremely obvious, resulting in unwanted color fringing around edges.

In this original photo the green spill is not immediately obvious to the naked eye:

Once the green screen is removed by PhotoKey, it is evident that there is green around the edges of her hair:

Here's a close-up view - note the green visible on the outside edge of the hair:

With PhotoKey's spill suppression turned on, the green tint is replaced with a neutral color, without the other colors being affected:

Again, here is a close-up of the same area:

The amount of spill will vary depending on the subject and your green screen setup. White clothing, for example, can be particularly susceptible to bounced green light.

There are multiple types of spill suppression, each of which can be fine tuned.

Apply

Spill suppression can be applied before or after Masks.

If applied before, any masks that are set to retain parts of the foreground will include the original coloring from the photo. This is useful if you are using masks to retain objects which are the same color as the screen, such as green clothing, where you need to also retain the original color.

If applied after, the entire image will be spill suppressed, including any masked areas set to retain parts of the foreground. This is useful if you are using masks to fix problems such as highly reflective materials or crystal, where you want to retain detail but remove green spill.

Spill method

There are five types of spill suppression: standard, extended, advanced, spill simulation and spill simulation pro.

In most cases spill simulation pro will provide the best results.

Spill simulation pro

The spill simulation pro method gives you fine control and replaces the original green spill with natural, simulated spill from your new background image. This creates the most realistic composite images.

View

You can switch to the despill view mode when using the spill simulation method. This shows exactly which parts of the image will be spill suppressed.

You can use the despill view to make sure that only the areas that need spill suppressing are affected. This can be very useful for avoiding discoloration of your subject.

Amount

Varies the strength of the spill suppression.

Hue range, balance & hue balance

These three sliders area used to adjust how much of the foreground image is affected by the spill suppression. They are best adjusted when in the despill view, so you can see how much is affected.

Luminance

The brightness of the background can be used to influence the brightness of the spill suppressed areas. The effectiveness of this will depend on the specific combination of lighting in your foreground and background.

Blur

The background is used to generate a new, realistic spill that replaces the original spill from the green screen. Increasing the blur generates a softer, more diffuse spill which doesn't correlate as directly with the background details.

Spill simulation

This method works similarly to Spill simulation pro, but instead of using the background image for the spill replacement it instead uses a single specified color.

The default is a neutral grey R128 G128 B128.

Standard, Extended and Advanced

These modes are provided primarily for legacy purposes. They remove spill using a less sophisticated method, with advanced providing specific control over each color channel.