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match badly-printed QR codes 

recognize QR codes despite smears caused by bad printers
This commit is contained in:
Alessandro Florio 2022-10-31 17:00:24 +01:00
parent 4f3a13fb2a
commit a48bc1dec5
1 changed files with 15 additions and 2 deletions
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17
src/zxing/zxing/qrcode/detector/QRFinderPatternFinder.cpp
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@ -87,11 +87,24 @@ bool FinderPatternFinder::foundPatternCross(int *stateCount)
int moduleSize = (totalModuleSize << 8) / 7; int moduleSize = (totalModuleSize << 8) / 7;
int maxVariance = moduleSize / 2; int maxVariance = moduleSize / 2;
// Allow less than 50% variance from 1-1-3-1-1 proportions // Allow less than 50% variance from 1-1-3-1-1 proportions
return ::abs(moduleSize - (stateCount[0] << 8)) < maxVariance && if ( ::abs(moduleSize - (stateCount[0] << 8)) < maxVariance &&
::abs(moduleSize - (stateCount[1] << 8)) < maxVariance && ::abs(moduleSize - (stateCount[1] << 8)) < maxVariance &&
::abs(3.0f * moduleSize - (stateCount[2] << 8)) < 3 * maxVariance && ::abs(3.0f * moduleSize - (stateCount[2] << 8)) < 3 * maxVariance &&
::abs(moduleSize - (stateCount[3] << 8)) < maxVariance && ::abs(moduleSize - (stateCount[3] << 8)) < maxVariance &&
::abs(moduleSize - (stateCount[4] << 8)) < maxVariance; ::abs(moduleSize - (stateCount[4] << 8)) < maxVariance
) {
return true;
}
// Proportions are not matched by the pattern. However, a bad print or a blurred frame
// may lead to a false negative. Try to check whether there is a valid center and the
// two extremities are of similar size, with blacks and whites having matching widths.
return ::abs(3.0f * moduleSize - (stateCount[2] << 8)) < 3 * maxVariance && // center is 3/7 +- variance
::abs(2.0f * moduleSize - ((stateCount[0] + stateCount[1]) << 8)) < 2 * maxVariance && // left/top is 2/7 +- variance
::abs(2.0f * moduleSize - ((stateCount[3] + stateCount[4]) << 8)) < 2 * maxVariance && // right/bottom is 2/7 +- variance
(::abs(stateCount[0] - stateCount[4]) << 8) < maxVariance && // difference between first and last black is < variance
(::abs(stateCount[1] - stateCount[3]) << 8) < maxVariance; // difference between whites is < variance
} }
float FinderPatternFinder::crossCheckVertical(size_t startI, size_t centerJ, int maxCount, int originalStateCountTotal) float FinderPatternFinder::crossCheckVertical(size_t startI, size_t centerJ, int maxCount, int originalStateCountTotal)