Features
Check transparency
Inspect any image’s alpha channel — see exactly which pixels are opaque, partial, or transparent before shipping a cutout.
What it does
Drop an image and the Check Transparency tool reports:
- Total pixel count
- Fully opaque pixel count (alpha = 255)
- Partially transparent pixel count (0 < alpha < 255)
- Fully transparent pixel count (alpha = 0)
- Whether the image has any transparency at all
- Whether the image has partial alpha (soft edges, anti-aliasing, glass / fur effects)
It also overlays a visualisation on the image: a magenta checkerboard appears wherever the image is transparent, and partial-alpha pixels are highlighted in semi-transparent red so you can see them at a glance.
When you'd use this
- Pre-flight checking a cutout — confirm the BG remover actually produced a transparent background (rather than a white background that looks transparent on a white page).
- Debugging a "Photoshop shows black" problem — see the why-my-export-shows-black-in-photoshop article for context.
- Auditing artwork received from a third party — many "transparent" PNGs from stock-image sites actually have a single solid colour baked into the background.
- Validating a Glass-mode cutout has preserved partial alpha (you should see partial-alpha pixels in the report; if all pixels are 0 or 255, the partial alpha was lost somewhere downstream).
Reading the numbers
A clean photographic cutout from NSS typically shows:
- ~50–70 % fully transparent (the removed background)
- ~25–45 % fully opaque (the solid subject body)
- ~2–10 % partial alpha (the anti-aliased edge of the subject)
If you see 0 % partial alpha on a photo cutout, somewhere in the export chain you lost the soft edges — possibly a JPEG re-encode, or a tool that thresholded the alpha to binary.
If you see 0 % transparent, the image has no transparency at all. This is normal for opaque JPEGs and for some PNGs / WebPs that were saved without an alpha channel.
Different from "is this a PNG"
A PNG file can support transparency but doesn't have to. A JPEG file cannot support transparency at all. The transparency check inspects the actual alpha channel of the decoded pixels — it doesn't just check the file extension or container.
That's why a "transparent PNG" you downloaded from somewhere can be reported here as fully opaque — the file format permitted transparency but the image inside has none.
Privacy
Decoding and analysis happens entirely in-browser.