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Stack Multiple Images Into One — Photoshop-Style Layer Compositing

Take a stack of images (with transparency) and flatten them into a single finished image, using alpha compositing — exactly like Photoshop's "Merge Visible." Automatically handles layers of different sizes with three fit modes (cover, contain, stretch) so a small logo, a full-frame photo, and a mid-size overlay can all live in the same composition without manual resizing. Perfect for watermarks, badges, overlays, subject-on-background compositing, and any workflow where you're combining separate image elements.

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What it does

Layer Compose takes a layer stack (multiple images, typically with alpha/transparency) and alpha-composites them into a single output image. The layers are stacked in order — later layers appear on top of earlier ones — and blended together using each layer's alpha channel. When a layer has a different resolution than the background, the tool automatically resizes it using the fit mode you choose. The result: one flattened image with all the layers combined, at the background's resolution.

Problem it solves

• Combine masked outputs – Composite a subject cutout (from SAM3 + Object Picker) back onto a new or blurred background
• Watermarks & logos – Stamp a transparent PNG logo onto photos without opening a graphics editor
• Badges & overlays – Add stickers, seals, banners, or corner badges to product images or thumbnails
• Portrait-mode compositing – Layer a sharp subject over a Lens-Blurred background for a shallow depth-of-field look
• Multi-element scenes – Combine background + subject + foreground effects into one image
• Handle mixed resolutions – Small logo, mid-size overlay, and full-frame photo all sit correctly without manual resizing
• Batch composite – Apply the same layered composition to many inputs without repeating placement work
• Fully alpha-aware – Respects transparency in every layer for clean, seam-free composites

Input/Output

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• Input: A stack of image layers
  • Format: Any image format; layers with alpha (PNG, RGBA) blend transparently
  • Layer order: First layer in the stack is the bottom (background); later layers are drawn on top
  • Resolution: Layers can be any size — differences are handled by the fit mode
  • Alpha: Fully respected — transparent pixels let underlying layers show through; partial transparency blends smoothly

• Options:

  • How to fit differently-sized layers to the background resolution:

    Controls what happens when a layer's dimensions don't match the background. Same idea as CSS object-fit.

    Mode	Behavior	Best For
    cover (default)	Layer is scaled to fully cover the background, cropping any overflow. Aspect ratio preserved.	Full-frame overlays where you want to fill every pixel, even if edges get trimmed
    contain	Layer is scaled to fit entirely inside the background, adding transparent letterboxing if needed. Aspect ratio preserved.	Logos, badges, or images you want to keep whole — no cropping
    stretch	Layer is stretched to exactly match background dimensions. Aspect ratio not preserved (image may distort).

• Output: Single composed image

  • Format: PNG (with alpha) — flattened composite of all input layers

  • Resolution: Matches the background layer's resolution

  • Content: All layers blended in stack order, with fit-mode-driven resizing applied to non-matching layers

    

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How to Use

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1. Prepare your layers → Set up the images you want to composite (background, subjects, overlays, watermarks). Layers with transparency should be PNG / RGBA.
2. Order matters → Arrange the layers in stack order — the first layer is the background (bottom); each subsequent layer is drawn on top of the previous one.
3. Connect to Layer Compose → Wire the layer stack into the Layer Compose node
4. Pick a fit mode → Choose cover (default), contain, or stretch based on how you want mismatched-size layers to be resized
5. Run Flow → All layers are alpha-composited into one output image at the background's resolution </aside>

Note: Layer Compose is the finishing step for any workflow that produces separate image elements — subject cutouts, blurred backgrounds, transparent overlays, badges, logos — and needs them merged into one final image. Pair it with SAM3 + Object Picker (for subject extraction), Lens Blur (for backgrounds), and Draw Text (for captions) to build a complete portrait-mode / hero-shot pipeline in a single flow. For pure text overlays without a separate image layer, Draw Text alone is simpler..