Most of them are probably lost due to the heavy compression applied... but extracting yellow dots from scanned documents is possible in theory. E.g. it was most

Most of them are probably lost due to the heavy compression applied... but extracting yellow dots from scanned documents is possible in theory. E.g. it was most likely the reason why Reality Winner got arrested so quickly after she gave NSA documents to the press: https://en.wikipedia.org/wiki/Reality_Winner https://en.wikipedia.org/wiki/Reality_Winner