Data encoding in printed material using varying IR reflective materials
Disclosed herein are methods and systems for encoding data in composite patterns such that the encoded data is perceptible in one or more infrared spectral ranges while significantly imperceptible in visible light spectral range by encoding the data in one or more first partial patterns and/or in one or more second partial patterns of the composite pattern where the first partial pattern(s) is painted using a first print material and the second partial pattern(s) is painted using a second. The first and second paint materials are characterized by reflecting substantially similar light in the visible light spectral range and significantly different light in the infrared spectral range(s) such that the first and second patterns are indistinguishable in the visible light spectral range while highly distinguishable in the infrared spectral range(s). further disclosed are methods and systems for decoding the composite patterns to decode and extract the encoded data.
1. A method of decoding data encoded in patterns perceptible in infrared spectral range, comprising:
using at least one processor for:
receiving at least one infrared image depicting, in at least one infrared spectral range, a composite printed pattern comprising at least a first partial pattern printed using a first paint material and a second partial pattern printed using a second paint material, the first and second paint materials are characterized by: (1) light reflected by the first paint material in visible light spectral range deviates less than a first value from the light reflected by the second paint material, and (2) light reflected by the first paint material in the at least one infrared spectral range deviates more than a second value from the light reflected by the second paint material;
analyzing the at least one infrared image to identify the first partial pattern and/or the second partial pattern separated from each other; and
decoding data encoded in the first partial pattern and/or in the second partial pattern;
wherein the first partial pattern and the second partial pattern are each composed of a plurality of blotches.
2. The method of claim 1 , wherein the first value equals 20% and the second value equals 35%.
3. The method of claim 1 , wherein the at least one infrared spectral range is a member of a group consisting of: near infrared (NIR) having a wavelength in a range of 750-1400 nanometer, and short wave infrared (SWIR) having a wavelength in a range of 1400-3000 nanometer.
4. The method of claim 1 , wherein the first partial pattern is distinguished from the second partial pattern according to a threshold of infrared light reflection in the at least one infrared spectral range applied to each of a plurality of pixels of the at least one infrared image,
wherein each pixel reflecting infrared light exceeding the threshold is mapped to one of the first pattern or the second pattern while each pixel reflecting infrared light not exceeding the threshold is mapped to the other pattern.
5. The method of claim 4 , wherein the threshold is selected in a range defined by the second value.
6. The method of claim 1 , further comprising applying at least one background flattening algorithm to flatten the at least one infrared image prior to the analysis.