More than a scanner

A phone camera reads a QR code that is plainly visible. Puzzle makers hide them: in the last bit of the blue channel, inverted, drawn in two nearly identical colors, or so faint they vanish. CacheCrack looks for codes in the picture itself and in the views where hidden ones turn up, including single colors, boosted contrast, black and white at several cutoffs, and the low bit planes, and tells you where it found each one.

Web links in a code get an Open button. Browsers that support it also read other barcodes, like Code 128, EAN and Data Matrix.

If nothing is found

A code cut into pieces or partly scratched out needs putting back together first. The Image layers tool can help you spot a code that is only visible in one layer.