Turbid, polluted, or insufficiently treated water or liquid will decrease the clarity of the media. The same occurs when smoke, soot, or other pollution impinges gaseous media.
Barcodes, 2D barcodes, QR codes are used through scanning to detect embedded data for tagging purposes. The process of scanning and identifying the codes requires pattern recognition. Thus regardless of the pattern, finer granularity will be harder to detect except in bright light conditions. This affect can be taken advantage of by having two or more codes, either separately printed, or superimposed on one another such that the smallest pattern that can be easily discerned under a particular brightness of light will tell how clear the media is.
The following pictures show a representation of three patterns that are QR or 2D Barcodes that would be placed in the media for pattern recognition.
Separate images.
Superimposed images.The size and pattern would be chosen so that differing ease of detection under controlled, calibrated, or known lighting conditions would indicate the clarity of the medium. Detection of the smallest patterns would only occur under the clearest conditions.
-- Mark Wright.
