Composite and finish existing images

The Nodespell composite-and-finish recipe builds one finished still from images you already have. You bring a foreground and a background into an Image Compositor, pull a matte with Keyer, match the foreground with Color Correct, place it with Transform, merge it over the background, then crop and download. Compositor nodes run in the editor, so this recipe uses no generation credits.

What you need

• A foreground image (for example, a subject shot on a green or blue screen, or a cutout from Remove Background).
• A background image.
• Both images in Asset Manager, or as results on nodes in your Project.

Graph at a glance: Background Asset + Foreground Asset → Image Compositor { Compositor Input → Keyer → Color Correct → Transform → Merge → Compositor Output } → Crop → download

Credits

Keyer, Color Correct, Transform, Merge, and Crop are image-processing nodes, not model runs, so they do not use credits. You spend credits only if you generate a missing ingredient, such as a background from Image Generator.

Stage 1: Bring the images into an Image Compositor

1. Open the Project in Graph mode.
2. Press Tab and add an Asset node for the background. Right-click it, choose Load Asset, and pick the background image. Repeat for the foreground.
3. Press Tab and add Image Compositor.
4. Connect the background Asset to the Image Compositor Images input first, then connect the foreground Asset. The connection order sets each image’s index: the first is 0, the second is 1.
5. Select the Image Compositor node and set Canvas size, for example First input to match the background, or a preset such as 1080p Landscape · 1920 × 1080.

Image Compositor is the still-image compositor; Compositor is the time-based version for video. See Compositing.

Stage 2: Pull the foreground matte

1. Select the Image Compositor and press Enter, or right-click it and choose Enter Node. A new compositor already contains a Compositor Input connected to a Compositor Output.
2. Select the existing Compositor Input and leave Index at 0. This is the background.
3. Press Tab and add a second Compositor Input. Set its Index to 1. This is the foreground.
4. Press Tab, add Keyer, and connect the foreground Compositor Input to it.
5. Choose the keying mode that matches the footage: Green Screen, Blue Screen, Red Screen, Chroma Distance, Luminance, or Saturation.
6. Adjust Screen Color, Clip Black, and Clip White until the background is clean and the subject is solid. Set Output to Matte View while you tune, then back to Write Alpha.

If the foreground is already a cutout with transparency, skip Keyer. Add Erode/Dilate after Keyer when the matte edge needs to shrink or grow. See Masks and keying.

Stage 3: Match the color and place the foreground

1. Add Color Correct after Keyer. Choose Mode (Lift Gamma Gain or Shadows Midtones Highlights) and use Color Wheels to match the foreground’s blacks, midtones, and highlights to the background.
2. Add Transform after Color Correct. Scale, move, and rotate the foreground into place. Choose a Filter (for example Lanczos 3) for sharper resampling.

See Color correction and Transforms and crop.

Stage 4: Merge and output

1. Add Merge.
2. Connect the background Compositor Input to Background and the Transform output to Foregrounds.
3. Leave Mode on Over to place the foreground on top. Lower the mix to blend it.
4. Connect the Merge output to Compositor Output, replacing the default connection from the first Compositor Input.
5. Press U to return to the parent graph.

Merge offers many blend modes, including Screen, Multiply, Overlay, and a Custom mode with expressions for Colour and Alpha. See Compositing.

Stage 5: Crop and download

1. Back in the parent graph, press Tab, add Crop, and connect the Image Compositor Image output to it.
2. Select Crop. Drag the handles in the Design panel viewer to set the frame. Hold Shift to lock the aspect ratio and Option/Alt to resize from the center.
3. Right-click the Crop node and choose Download.

See Export for download options.

Check the result

• Select the Image Compositor. The Design panel shows the composite, and you can zoom to inspect the matte edge.
• Temporarily set Keyer Output to Matte View and look for gray holes in the subject or specks in the background.
• Select the original foreground Asset and the Crop node together to compare them as A and B in the Design panel.

Variations

• Several foregrounds. Connect more images to Images (indices 2, 3, …) and feed each prepared layer into Foregrounds of the same Merge.
• Grade the whole frame. Add Color Correct or Grade after Merge, inside the compositor, so the correction applies to the assembled image.
• Composite a video shot. Use Compositor instead of Image Compositor when the background or foreground is a video, then render and download its video output.
• Add depth effects. Feed a depth map into the same compositor and add ZDefocus or Depth Atmosphere; see Refocus with depth and add atmosphere.

Frequently asked questions

Why does my compositor show only the background?

The default Compositor Output is connected to the first Compositor Input. Connect the Merge output to Compositor Output instead.

How does a Compositor Input know which image to use?

Index is a zero-based position in the parent compositor’s Images input, in connection order. The first connected image is 0.

Can I use Keyer outside a compositor?

Yes. Keyer, Color Correct, Transform, and Crop also work in the main graph. Merge and Compositor Input work only inside a compositor.

How do I get back out of the compositor?

Press U to go up one level to the parent graph.

Related

• Compositing — compositor types, inputs, and Merge modes
• Masks and keying — Keyer and matte tools in depth
• Color correction — Color Correct, Curves, and Hue Correct
• Transforms and crop — Transform, Resize, and Crop
• Export — download finished media