Core Tools
Exporting with transparency
How to export a PNG, WebP, or AVIF with true alpha channel transparency.
What "true transparency" means
A transparent image isn't just a file with a missing background — it has an alpha channel that records, for every pixel, exactly how opaque it is. Values range from 0 (fully transparent) to 255 (fully opaque), with every value in between for soft, anti-aliased edges.
NSS always exports straight alpha (unassociated alpha). This is the correct format for professional tools like Photoshop, Figma, and Affinity. Many other tools export premultiplied alpha by mistake, which causes the black-background problem in Photoshop. See Why does my export show black in Photoshop?.
Exporting from the editor
- Open your processed image in the editor
- Make any brush or edge refinement adjustments
- Click Export in the top-right corner
- Choose your format:
- PNG — lossless, universal, always correct transparency
- WebP — smaller files, excellent quality, great browser support
- AVIF — smallest files, excellent quality, Chrome/Firefox/Safari 16.4+
- JPG — no transparency; composites onto your background colour
- Set quality (for WebP/AVIF — 80 is a good default)
- Choose filename (defaults to
{original-name}-nobg.{ext}) - Click Download
Integrity check
After encoding, NSS automatically decodes the file and samples 100 pixels to verify the alpha channel is correct. If anything looks wrong (premultiplied alpha, binary alpha that should be soft), you'll see a warning before the download. This check runs on every export.
Format comparison
| Format | Transparency | Lossy | File size | Tool support |
|---|---|---|---|---|
| PNG | Yes | No | Large | Universal |
| WebP | Yes | Yes | Medium | Most tools |
| AVIF | Yes | Yes | Small | Modern tools |
| JPG | No | Yes | Small | Universal |
Batch export
Processing multiple images? Click Export all at the top of the queue. All processed images are packaged into a ZIP file and download in one click. Each file uses the format and settings you last configured.
Checking your export
To verify transparency is working correctly:
- In a browser: drag the PNG onto a new tab — you should see a checkerboard
- In Photoshop: File → Open → drag the PNG. No black background means straight alpha is correct
- In Figma: import the PNG — it should show no background immediately
- On Windows: right-click → open with Photos — transparent areas show as white (Photos doesn't show checkerboard, but the file is still correct)