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.
Related
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