Tween Node

Tween takes two images as input (Input 0 = frame A, Input 1 = frame B) and generates an in-between frame at a position set by the Interpolation Parameter (0 = frame A, 1 = frame B, 0.5 = midpoint).

Very flexible, since you can tween between any images, not only adjacent frames of a video. Use cases: a smooth transition between two stills, simple slow motion through animated interpolation.

• Effects Library: Tools > Optical Flow > Tween
• Quick add: right-click in the Node Editor → Add Tool > Optical Flow > Tween

Time Stretcher

Works on a video sequence with an animatable Source Time. For classic retiming.

Tween

Works on two arbitrary images (not necessarily sequential). More flexible for specific interpolations.

Rule of thumb: retiming a video sequence → Time Stretcher. Interpolating between 2 non-sequential images → Tween.

• Input 0 (orange) - the "previous" frame.
• Input 1 (green) - the "next" frame.
• Effect Mask (blue) - optional. Limits the interpolation to specific areas.

Smooth transition between 2 stills:
ImageA (still) ─┐
                ├── Tween (Interpolation animated 0 → 1 over 60 frames)
ImageB (still) ─┘
                  → MediaOut
   = a smooth A → B morph over 60 frames

Frame interpolation for slow motion:
Frame N ────┐
            ├── Tween (Interpolation = 0.5)
Frame N+1 ──┘    → in-between frame at 0.5
                = doubles the effective frame rate

With a color correction match:
ImageA → Color Correct ─┐
                        ├── Tween → Output
ImageB → Color Correct ─┘
   = pre-color match for a better OF

Interpolation Parameter (default: 0.5)

Position of the generated frame between the sources. 0 = pure frame A, 1 = pure frame B, 0.5 = midpoint. Animate it for a transition.

Depth Ordering

Fastest On Top / Slowest On Top. Render priority based on the speed of the motion vectors.

Clamp Edges

Removes transparent edge gaps. Can introduce stretching.

Edge Softness (default 0.01-0.03)

Reduces the stretching artifacts from Clamp Edges.

Source Frame & Warp Direction

Four checkboxes: Prev Forward, Next Forward, Prev Backward, Next Backward. They can be blended for a robust interpolation.

Optical Flow Options

Standard OF parameters (Classic / Advanced).

The Settings tab is shared with the other Optical Flow nodes and exposes common blending and masking controls:

Blend (0.0 - 1.0)

Mix between the input and the generated tween. 0 = pure input (frame A or B depending on Interpolation), 1 = full tween.

Process When Blend Is 0.0

Processes the node even when Blend = 0 (scripted).

RGBA Channel Selectors

Limit the tween to specific channels.

Apply Mask Inverted / Multiply by Mask

Mask channel options.

Use Object / Use Material

Enables Object/Material IDs as masks. Sliders + Sample button.

Correct Edges

Edge toggle for multi-object images.

Hide Incoming Connections

Hides the wires for a clean graph.

Comments / Scripts

Annotation + 3 render-time script fields.

• Transition between 2 stills - two similar photos: Tween + animated Interpolation = a smooth morph.
• Slow motion on limited footage - doubles the frame rate by interpolating between adjacent frames.
• Custom frame interpolation - you need to generate a specific frame between two non-sequential frames: Tween directly.
• Smooth scene transitions - two different scenes: Tween for an organic transition instead of a simple dissolve.
• Stop motion / 2D animation - interpolation between 2 key drawings to animate more smoothly.

• Pre-color match - images A and B with very different colors: OF struggles. Color correct them first to match before the Tween.
• Pre-denoise for a clean OF - noise in the sources makes the OF worse. Remove Noise upstream = a better result.
• Interpolation 0.5 = midpoint - start there, animate it if you need a transition.
• Use Clamp Edges sparingly - only for minor edge gaps.
• OF limits - Tween works on similar images. If A and B are radically different, the OF fails (same limits as the standard Optical Flow).
• Cache the output - Tween is heavy (internal OF). Cache it to reuse it without recomputing.
• For whole sequences, prefer Time Stretcher with a cacheable external Optical Flow.