Qwen Image 2.1 secretly adds alpha channels, inflating file size by 15-20%
Calm_Mix_3776 · reddit · 2026-09-24
A user found that Qwen Image 2.1 saves images with alpha channel information even when transparency isn't needed — generating a flat image or editing a non-transparent one still outputs an alpha-channel PNG, inflating file size by roughly 15-20% per image.
Fix: in ComfyUI, insert a "Split Image with Alpha" node between VAE Decode and your save node to strip the channel before saving.
Related event: Qwen Image 2.1 Adds Unneeded Alpha Channel, Bloating Files 15-20%(2 posts)→
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