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

Image Mask Crop - Mask-Boundary Cropping and Alpha Output

Node Purpose: Image Mask Crop crops by the mask’s bounding box or keeps original size, and optionally outputs alpha from the mask. Returns both the image and the processed mask, with robust batch size alignment.

Inputs

Name	Port	Type	Default	Range	Description
image	-	IMAGE	-	-	Input image batch.
mask	-	MASK	-	-	Input mask batch.
output_crop	-	BOOLEAN	true	-	Crop to the mask’s bbox; when false, keep original image size.
output_alpha	-	BOOLEAN	false	-	Output RGBA with alpha from the mask when true; otherwise output RGB.

Outputs

Name	Type	Description
image	IMAGE	Cropped or original-size image; RGBA if output_alpha is true.
mask	MASK	Cropped or padded mask aligned to the image output.

Features

• BBox cropping: computes bbox from mask and crops image/mask accordingly.
• Alpha channel: when output_alpha is true, the mask is written into the image alpha.
• Size preservation: when output_crop is false, keeps original size and centers/pads the mask if needed.
• Batch robustness: mismatched image/mask counts are cycled; outputs are padded to uniform sizes before stacking.

Typical Usage

• Matte extraction: set output_alpha=true to produce RGBA cutouts; downstream compositing can use alpha directly.
• Tight crops: set output_crop=true to focus on the mask region; output_alpha=false to keep RGB only.
• Full-frame effects: set output_crop=false to maintain the original canvas while applying mask alpha.

Notes & Tips

• If the mask has no non-zero pixels, the node falls back to original-size outputs and applies alpha (if enabled).
• RGBA inputs are converted to RGB before cropping unless output_alpha is requested.
• Outputs are device-safe and clamped to [0,1].