ComfyUI Extension: comfyui-klein-edit-composite

Klein Edit Composite — ComfyUI Custom Node

What it does

This is a ComfyUI node that intelligently composites a generated (AI-edited) image back onto an original image. Its core job is to detect only what actually changed between the two images and blend the generated content in cleanly — preserving the original background wherever it wasn't meaningfully altered.

Series of edits without the node:

Series of edits with the node:

How it works

The pipeline runs roughly in this order:

1. Alignment (Two-Pass SIFT + Homography): Uses SIFT feature matching with CLAHE preprocessing and MAGSAC outlier rejection to correct any camera/perspective shift between the original and generated image. A second pass refines alignment using only background pixels.

2. Optical Flow (DIS): After homography correction, dense optical flow catches any remaining sub-pixel or local motion between the two images.

3. Difference Detection: Computes a hybrid diff map combining perceptual color difference (Delta E in LAB color space) and structural difference (Sobel gradient magnitude). This makes it robust to minor lighting shifts while still catching real content changes.

4. Mask Refinement: The raw change mask is cleaned up via noise removal (opening-by-reconstruction), hole filling, island pruning, border bleed, and optional grow/shrink. An optional occlusion mask (forward-backward flow consistency check) can also be incorporated.

5. Color Matching: Optionally applies Reinhard color transfer (in LAB space) to match the generated image's lighting/color to the original, using only background pixels for statistics.

6. Compositing: The final mask is feathered using a guided filter (edge-aware smoothing) and used to alpha-blend the generated image over the original.

Outputs

• composited_image — the final blended result
• change_mask — the detected change region
• report — a text summary of all parameters and statistics
• debug_gallery — optional visual breakdown of intermediate steps (SIFT matches, flow, diff maps, etc.)

AI coded, I am not a developer.