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

Image Alpha Join - Combine image and alpha

Node Purpose: Image Alpha Join combines optional image and mask inputs into a single 4-channel IMAGE output for producing RGBA images with alpha.

Inputs

Name	Port	Type	Default	Range	Description
image	-	IMAGE	-	-	Optional input image, supports single image or batch; if it already contains alpha, only the RGB channels are used
mask	-	MASK	-	0~1	Optional alpha mask; when provided together with image, it becomes the output alpha channel
invert_mask	-	BOOLEAN	true	true / false	Whether to invert mask before writing it into alpha; enabled by default

Outputs

Name	Type	Description
image	IMAGE	Combined 4-channel image (RGBA)

Features

• Both empty: returns an empty output.
• Only image: fills alpha with full white so the whole image stays visible.
• Only mask: returns a fully transparent image using the mask size only and ignoring its values.
• Both image and mask: combines the RGB from image with alpha from mask; when invert_mask=true, the mask is inverted first.
• Size mismatch: resizes mask to the image size with nearest-neighbor sampling.
• Batch support: when one side has a shorter batch, frames are reused in order.

Typical Usage

• Rebuild RGBA images from a regular image plus a separate mask.
• Quickly add a full alpha channel when a downstream workflow expects 4-channel IMAGE input.
• Keep RGBA pipeline dimensions consistent with transparent placeholder outputs.

Notes & Tips

• The output is always a 4-channel IMAGE.
• If the image input already contains alpha, this node does not preserve that original alpha; it uses the external mask or the default full-white alpha instead.
• invert_mask is enabled by default, which is more convenient for workflows where white means "remove/make transparent"; disable it if your mask already represents the intended alpha directly.