1hew-ComfyUI-1hewNodes/web/docs/1hew_ImageAlphaSplit/en.md

Image Alpha Split - Extract alpha and flatten to background

Node Purpose: Image Alpha Split extracts the input image alpha as a mask output, while also compositing transparent areas onto background_color and returning the processed RGB image.

Inputs

Name	Port	Type	Default	Range	Description
image	-	IMAGE	-	-	Input image, supports single image or batch; RGBA inputs extract alpha and composite against the background color; both outputs are empty when it is empty
background_color	-	STRING	1.0	named / #RRGGBB / r,g,b / 0~1 grayscale / single-letter shorthand / sm	Background color used to fill transparent areas; sm selects black, white, or #808080 per frame for subject and edge visibility

Outputs

Name	Type	Description
image	IMAGE	RGB image flattened onto the selected background
mask	MASK	Alpha mask extracted from the input image; becomes a full-white mask when the input has no alpha

Features

• Empty image (unconnected or a zero-length batch): both the image and mask outputs are empty.
• RGBA input: returns the original alpha as mask and composites transparency onto background_color; with sm, it selects black, white, or #808080 per frame based on composited subject and translucent-edge visibility.
• RGB input: passes image through unchanged and returns a full-white mask.
• Batch support: image batches are processed frame by frame and return synchronized image and mask outputs.
• Color parsing follows the same rules as the Image Solid node.

Typical Usage

• Split alpha from transparent PNGs while also generating a background-filled preview or downstream-safe RGB image.
• Prepare white-background images for nodes that do not support alpha, while keeping the transparent area as a mask.
• Standardize batch workflows that need both a flattened image and the original alpha mask.

Notes & Tips

• The image output is always RGB and does not preserve the original alpha channel.
• If the input image has no alpha channel, mask becomes fully white and background_color does not affect the image result.
• When image is empty no placeholder is built: both image and mask are returned empty so downstream branches can short-circuit.