A cutout can look white when opened in a photo viewer even if its background is transparent. The viewer chooses what to draw behind empty pixels. A white-looking preview alone cannot distinguish transparent pixels from solid white ones.
We made a two-pixel transparent PNG, then flattened it onto white and saved a JPG. Comparing the actual alpha values verifies the format distinction, not the quality of an automatic background-removal model.
Make these distinctions first
A viewer may show empty space against white.
Try a checkerboard and a contrasting color.
JPG cannot retain the transparent alpha channel.
We read stored transparency values
- 1
We created a 2×1 image in code: the first pixel had alpha 0 (fully transparent) and the second alpha 255 (opaque), then saved it as PNG. No personal or product images were used.
- 2
We decoded the PNG to inspect the two alpha values. Next, we explicitly flattened it against white, saved it as JPG, and decoded that file. The reproducible script is scripts/measure-ocr-and-alpha.mjs.
- 3
The PNG returned alpha 0 and 255. Reading the white-background JPG yielded opaque 255 for both pixels. The JPEG decoding step supplies an opaque alpha channel; the white flattening was an explicit part of this test.
The same apparent white can mean different pixels
The first PNG pixel looks white on a white page, but the file still says ‘empty here’. Place it over blue and blue shows through. The flattened JPG contains a solid background pixel that remains white even on blue.
| File | First pixel | Second pixel | On another backdrop |
|---|---|---|---|
| Transparent PNG | Alpha 0: transparent | Alpha 255: opaque | Background shows through first pixel |
| JPG flattened on white | Opaque | Opaque | White remains at first pixel |
How to inspect your own cutout
In Toolit's result preview, switch between checkerboard, white, and dark. If the space around your subject follows the preview backdrop, that space is displayed as transparent. After downloading, place the PNG over a different color in an editor or document too.
A pale fringe that stays pale on every backdrop may be leftover source background rather than a viewing issue. Also watch for parts of a pale subject that were cut away. Review the edge where the image will actually be used.
Where PNG can lose its advantage
A messaging app, document editor, or photo app may turn a PNG into JPG or flatten it during paste/export. Renaming the resulting file to .png cannot restore lost transparency.
Keep the PNG downloaded by the remover as your original cutout. Check the destination after upload or insertion. We did not test every service's conversion policy in this experiment.
What this tiny test cannot tell us
Two pixels demonstrate how alpha works, not whether a real cutout preserves hair, shadow, or glass well. Viewers also choose different colors for empty areas. Check actual edges and the final destination separately.
Official documentation used for this analysis
Check on a contrasting backdrop before calling it a failure
Our PNG kept transparent alpha while the copy explicitly flattened on white and saved as JPG did not. If your cutout appears white, first view it on a checkerboard or another color.
Save the remover's PNG unchanged and inspect it in the destination. Leftover white fringe and transparency lost through format conversion are different problems with different fixes.