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Simple check in Code 39 reader to determine wide bars vary in width a lot, to cut out most false positives

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git-svn-id: https://zxing.googlecode.com/svn/trunk@442 59b500cc-1b3d-0410-9834-0bbf25fbcc57
This commit is contained in:
srowen 2008-06-18 22:52:45 +00:00
parent 180e833b3e
commit 15f34edb52
2 changed files with 17 additions and 1 deletions
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16
core/src/com/google/zxing/oned/Code39Reader.java
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@ -216,14 +216,30 @@ public final class Code39Reader extends AbstractOneDReader {
} }
maxNarrowCounter = minCounter; maxNarrowCounter = minCounter;
wideCounters = 0; wideCounters = 0;
int totalWideCountersWidth = 0;
int pattern = 0; int pattern = 0;
for (int i = 0; i < numCounters; i++) { for (int i = 0; i < numCounters; i++) {
int counter = counters[i];
if (counters[i] > maxNarrowCounter) { if (counters[i] > maxNarrowCounter) {
pattern |= 1 << (numCounters - 1 - i); pattern |= 1 << (numCounters - 1 - i);
wideCounters++; wideCounters++;
totalWideCountersWidth += counter;
} }
} }
if (wideCounters == 3) { if (wideCounters == 3) {
// Found 3 wide counters, but are they close enough in width?
// We can perform a cheap, conservative check to see if any individual
// counter is more than 1.5 times the average:
for (int i = 0; i < numCounters && wideCounters > 0; i++) {
int counter = counters[i];
if (counters[i] > maxNarrowCounter) {
wideCounters--;
// totalWideCountersWidth = 3 * average, so this checks if counter >= 3/2 * average
if ((counter << 1) >= totalWideCountersWidth) {
throw new ReaderException("Wide bars vary too much in width, rejecting");
}
}
}
return pattern; return pattern;
} }
} while (wideCounters > 3); } while (wideCounters > 3);

2
core/test/src/com/google/zxing/common/FalsePositivesBlackBoxTestCase.java
View file

@ -35,7 +35,7 @@ import java.io.IOException;
public final class FalsePositivesBlackBoxTestCase extends AbstractBlackBoxTestCase { public final class FalsePositivesBlackBoxTestCase extends AbstractBlackBoxTestCase {
// This number should be reduced as we get better at rejecting false positives. // This number should be reduced as we get better at rejecting false positives.
private static final int FALSE_POSITIVES_ALLOWED = 23; private static final int FALSE_POSITIVES_ALLOWED = 15;
// Use the multiformat reader to evaluate all decoders in the system. // Use the multiformat reader to evaluate all decoders in the system.
public FalsePositivesBlackBoxTestCase() { public FalsePositivesBlackBoxTestCase() {