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

Image Batch Extract - Select frames by index/step/uniform

Node Purpose: Image Batch Extract selects specific frames from an input image batch using three modes: explicit index list, fixed step, or uniform sampling across the batch. Supports negative indices, large-batch chunked selection, and optional capping via max_keep.

Inputs

Name	Port	Type	Default	Range	Description
image	optional	IMAGE	-	-	Input image batch.
mode	-	COMBO	step	index / step / uniform	Selection mode.
index	-	STRING	0	comma list	For index mode; comma-separated integers, supports negative indices (e.g., -1).
step	-	INT	4	1-8192	For step mode; take every step frames.
uniform	-	INT	4	0-8192	For uniform mode; select uniform frames evenly across the batch; 0 selects none.
max_keep	-	INT	10	0-8192	Cap number of selected frames; 0 keeps all.

Outputs

Name	Type	Description
image	IMAGE	Batch containing only the selected frames.

Features

• Index parsing: accepts English/Chinese commas; negative indices resolve relative to batch size.
• Step selection: pick frames at fixed stride step starting from 0.
• Uniform sampling: evenly distribute uniform picks between 0 and batch_size-1.
• Robust filtering: invalid indices are skipped; returns empty batch when no valid indices remain.
• Chunked gather: selects in chunks (size 512) to reduce memory spikes on large lists.

Typical Usage

• Extract keyframes every N frames: set mode=step, step=N.
• Uniform thumbnails: set mode=uniform, uniform=K to sample K frames across the batch.
• Custom list: set mode=index, index=0, 2, 10, -1 to include specific frames including the last.

Notes & Tips

• max_keep=0 keeps all selected frames; set >0 to cap the output size.
• If all indices are out of range, the output is an empty batch with matching dtype/device.