What transparent pixels mean
A PNG stores an alpha value for every pixel: fully opaque shows the subject, fully transparent shows whatever sits behind the image, and partial alpha creates smooth anti-aliased edges. That is what lets one cutout work on any background.
Soft material — fur, steam, defocused edges — needs partial alpha. Forcing every pixel to fully-visible or fully-invisible turns a photo into a sticker.
Which formats keep transparency
If a service converts your upload to JPG, transparency is gone no matter how carefully you exported.
| Format | Alpha channel | Watch out for |
|---|---|---|
| PNG | Yes — full 8-bit alpha | The safe master format. Larger files than JPG. |
| WebP | Yes | Great for the web; some older tools flatten it on import. |
| JPG / JPEG | No | Converting to JPG replaces transparency with a solid color — usually white. |
| GIF | 1-bit only | A pixel is fully on or off; soft edges turn jagged. |
Export and verify the actual file
- Remove and inspect
Run the automatic pass, then check the result on white and gray previews — halos and leftover fragments hide on the checkerboard.
- Confirm internal gaps
Food, bicycles, furniture, and handles have openings that must be transparent. A connected background patch inside an opening is a one-stroke smart-erase fix.
- Download as PNG
The BGCut download keeps the alpha channel. Do not re-save it through an editor or messenger that flattens transparency.
- Verify at the destination
Drop the file onto a colored background in your design tool. A white thumbnail in the file browser proves nothing — previews often render alpha as white.
Delivery checklist
- The file extension is .png — not a renamed JPEG.
- The result was viewed over at least one light and one dark background.
- Internal openings and gaps around the subject are actually transparent.
- Semi-transparent edges look smooth, with no color fringe from the old background.
- The transparent master is stored separately from any flattened copy.