workflow-templates-broken-zap-2026-06-08/site/knowledge/nodes/custom/JoinImageWithAlpha.md

JoinImageWithAlpha

Category: mask/compositing

Display Name: Join Image with Alpha

Also known as: add transparency, apply alpha, composite alpha, RGBA

Description

This node is designed for compositing operations, specifically to join an image with its corresponding alpha mask to produce a single output image. It effectively combines visual content with transparency information, enabling the creation of images where certain areas are transparent or semi-transparent.

Inputs

Parameter	Type	Default	Description
image	Image	—
alpha	Mask	—

Outputs

Output	Type
)],
)

@classmethod
def execute(cls, image: torch.Tensor, alpha: torch.Tensor) -> io.NodeOutput:
    batch_size = min(len(image), len(alpha))
    out_images = []

    alpha = 1.0 - resize_mask(alpha, image.shape[1:])
    for i in range(batch_size):
       out_images.append(torch.cat((image[i][:,:,:3], alpha[i].unsqueeze(2)), dim=2))

    return io.NodeOutput(torch.stack(out_images) | Image |

Source: comfy_extras/nodes_compositing.py

Used in 1 template(s)