Dissolve

Purpose. Dissolve combines two image streams into one output and makes their transition animatable in a Fusion graph. It is useful for title state changes, before/after grades, and node-controlled transitions.

The basic graph is MediaIn A → Background, MediaIn B → Foreground and Dissolve.Output → MediaOut. In normal Dissolve, Background/Foreground at 0 shows A and 1 shows B; 0.5 is a useful midpoint check.

Ports have distinct meanings. Background, Foreground and Gradient Map accept images; Effect Mask accepts a mask. All three image ports are optional. Do not treat these sockets as four interchangeable layers.

Missing inputs. When either main image is unavailable on a frame, Dissolve can pass the remaining image regardless of the slider. That makes it a simple automatic switcher, but clip boundaries still need testing in the actual graph.

Operation is one dropdown, not multiple nodes. The captured screenshot contains eight entries: Dissolve, Additive Dissolve, Erode, Random Dissolve, Random Noise Dissolve, Alpha Merge, Gradient Wipe and SMPTE Wipe. The Resolve 21 reference documents seven of them.

Normal Dissolve is a conventional crossfade: A fades out as B fades in. Start with this operation, verify A/B wiring and keys, then move to more stylized choices.

Additive Dissolve brings in the second image before the first has fully receded. Its midpoint may be brighter than either endpoint; inspect highlights, HDR range and clipping on scopes.

Erode reveals B as the darkest regions of Background spread, producing a burnt or corroded film appearance. Unlike a uniform opacity fade, it responds to the content of A.

Random Dissolve reveals B through a random point pattern. Random Noise Dissolve uses a moving random point pattern; playback is needed to understand their different temporal behavior.

Gradient Wipe uses the luminance of a third image at the Gradient Map socket to define the spatial reveal order. Background/Foreground still governs overall progression; the map determines which regions reveal earlier.

Gradient Map can receive a gradient, FastNoise, a texture, water footage or another image. A nearly flat map produces little spatial variation; inspect and improve map contrast before altering the transition timing.

Effect Mask does not replace Gradient Map. The mask limits where the Dissolve result affects the image, while Gradient Map shapes the Gradient Wipe itself. Test them as separate inputs to understand the difference.

SMPTE Wipe generates its own geometric transition, without requiring a third map. The reference documents horizontal left-to-right and vertical top-to-bottom styles; Wipe Style selects a pattern and Invert Wipe reverses direction.

Wipe controls are conditional. Softness feathers the Gradient/SMPTE wipe edge. Border adds a colored edge; Border Softness and Border Color become available when Border is enabled.

Softness is not a full-frame blur of source A or B; it widens the zone where the two images meet. Start with a small value for a crisp wipe and increase it only as needed.

Border Softness changes the width and density of the colored edge. Adjust it after Softness and Border Color to separate edge decoration from the softness of the underlying transition.

Alpha Merge is visible as an eighth Operation entry in the original Inspector screenshot, but the Resolve 21 Composite Nodes chapter does not describe its compositing formula. Do not assume it matches standard Merge, straight-alpha or premultiplied-alpha until tested in the target build.

Input resolution and pixel aspect should be normalized before Dissolve. With mismatched sizes, the output can inherit the active endpoint dimensions at 0 or 1 and jump to the larger canvas while mixing.

Output domain changes can affect downstream Transforms, masks and layout. For robust graphics templates, normalize Background, Foreground and Gradient Map to a consistent frame format first.

Check transparent edges separately: a transition can reveal poor source alpha preparation or premultiplication. Inspect the midpoint over a checkerboard and compare against the upstream sources.

Mask example: Rectangle → Effect Mask confines the SMPTE transition to a selected area, but the rectangle does not define the wipe geometry. Check the mask polarity and the underlying wipe controls independently.

Dissolve versus Merge. Dissolve works well for an animated A↔B state transition or clips of different duration; Merge is built for persistent foreground-over-background compositing with more layer positioning and blend controls.

Animation quality. Inspect the start, midpoint and end before adjusting Spline interpolation. With Random Noise and Gradient Wipe, preview adjacent frames to catch erratic reveal patterns or distracting edge motion.

Validation boundary. Screenshots establish the Controls layout and eight visible menu entries. Conditional wipe controls, switcher behavior, changing output domains and Alpha Merge still merit a live test in the installed Resolve version; source review alone is not a render test.