Extend

Start X/Y defines where the propagation begins, while Direction chooses whether values extend horizontally or vertically.

Channel and Range Low/High determine which data is evaluated and which values are allowed to participate in the extension.

Hold can maintain a chosen value through the operation, making Extend useful in matte and utility-map workflows where predictable channel behavior matters.

**Verified identity.** This is Krokodove Extend integrated with Resolve 21, not native Crop, Transform, Resize, CleanEdges or GrowColor. Blackmagic describes horizontal/vertical pixel replication; the legacy Krokodove guide lists Direction, Channel and Hold. Exact internal algorithms and edge behavior for the current host cannot be inferred from Inspector PNGs.

**What the original images prove.** Controls shows Start X=0.5/Y=0.5, Horizontal, Channel Each, Range Low=0/High=1 and Hold Maximum. Those are captured node values, not a universal preset or factory defaults. Channel and Hold menus are open; the dim-looking alternatives do not by themselves establish that they are disabled.

**Start and direction.** Start X and Y form one point on the canvas. Explore X first for Horizontal, Y first for Vertical; do not assume the other component is mathematically unused in every mode. The reference describes the propagation axis, not an exact sampling kernel. Inspect a synthetic grid and animate one coordinate at a time.

**Channel chooses data, not output datatype.** Red/Green/Blue/Alpha/Luminance select the source component and Each means per-channel processing. Even when Alpha is selected, Extend.Output remains a regular image stream, not a typed blue mask output. Insert Bitmap.Image → Bitmap.Mask before another tool’s EffectMask socket.

**Range Low/High is not Crop.** The two limits apply to candidate values from the selected Channel, not to geometric bounds. The screenshot shows 0–1, but does not reveal an inclusive/exclusive comparison or behavior for out-of-range samples. Compare two branches of the same test gradient, fixing Start, Direction, Channel and Hold.

**Hold options share one selector.** Within range, Minimum and Maximum appear in the supplied UI and legacy Krokodove reference. Minimum is not a darkening knob, and Maximum is not a strength slider. They control how candidate values are held; pixel-exact behavior must be verified with an A/B in the target build rather than invented from labels.

**Effect Mask versus the source Channel.** If exposed by the target installation, a blue Effect Mask would limit where Extend contributes. Selecting Alpha inside Channel instead chooses source image data to process. These are separate tasks. All three supplied captures show only Inspector; they do not verify the physical mask socket or its wire in Node Editor.

**Where Extend is practical.** Start with procedural graphics, stripes, or narrow edge padding instead of claiming it is a seamless face repair or full clean-plate tool. Real footage can form repeated horizontal or vertical streaks. Limit the affected region, compare RGB/Alpha and retain a clean parallel branch.

**Animation and QA.** Diamonds beside controls are shared keyframe widgets, not an extra Extend-specific processing parameter. Animate Start smoothly and retain frame-specific settings; switching Channel/Direction/Hold mid-shot can cause abrupt discontinuities. Acceptance should cover 24–48 moving frames, alpha edges and final output dimensions, not just one Inspector capture.

**Evidence boundaries.** The package includes three original PNGs, Blackmagic’s effect summary and a legacy Krokodove reference. Unverified: actual image/mask sockets in Resolve 21, the closed Settings panel, grey-looking choices, exact sampling math and GPU-render stability. The typed exercises below are conceptual graphs, not exported .comp files or live-render evidence.

To establish a reliable reference, build a simple Text+ / Background image and inspect how the same input behaves when only Direction or Start changes. Use 100% Viewer and a known canvas aspect ratio rather than assuming all stretched images must look identical.

For compositing, feed the processed image into Merge or ColorCorrector as an image. When a blue mask port is required, use an explicit Bitmap node and choose the channel or luminance used to construct its mask output.

The most misleading exercise is to route a Polygon or Ellipse mask stream directly into Extend.Image; that is a type mismatch, not evidence that Extend does not work. Convert the mask to image data first if the specific task needs it.