Decoding QR codes ​​fails if the background is darker than the foreground

[sorairolake]

rqrr can decode QR codes if the background is lighter than the foreground:

However, if the background is darker than the foreground, QR codes cannot be decoded:

The results of decoding these QR codes are expected to be "QR code".

The second QR code is invalid as ISO/IEC 18004, but seems to be valid as JIS X 0510.

JIS X 0510ではQRコードの白黒を反転させることも認められているが[8]、ISO/IEC 18004では白黒を反転させる行為は許されていない。¹

See also sorairolake/qrtool#633.

Footnotes

1. Wikipedia contributors. (2024, November 3). QRコード. In Wikipedia. Retrieved 03:08, November 5, 2024, from https://ja.wikipedia.org/w/index.php?title=QR%E3%82%B3%E3%83%BC%E3%83%89&oldid=102444766 ↩

[rmader]

I can confirm this in the context of Snapshot, the Gnome camera app which is now shipping rqrr by default (thanks for providing it!). In particular when trying to scan from apps on setups with dark mode, the QR code detection is less reliable compared to light mode.