// Applies simple sharpening to the row data to improve performance of the 1D Readers.
@Override
public BitArray getBlackRow(int y, BitArray row) throws NotFoundException {
LuminanceSource source = getLuminanceSource();
int width = source.getWidth();
if (row == null || row.getSize() < width) {
row = new BitArray(width);
} else {
row.clear();
}
initArrays(width);
byte[] localLuminances = source.getRow(y, luminances);
int[] localBuckets = buckets;
for (int x = 0; x < width; x++) {
int pixel = localLuminances[x] & 0xff;
localBuckets[pixel >> LUMINANCE_SHIFT]++;
}
int blackPoint = estimateBlackPoint(localBuckets);
int left = localLuminances[0] & 0xff;
int center = localLuminances[1] & 0xff;
for (int x = 1; x < width - 1; x++) {
int right = localLuminances[x + 1] & 0xff;
// A simple -1 4 -1 box filter with a weight of 2.
int luminance = ((center * 4) - left - right) / 2;
if (luminance < blackPoint) {
row.set(x);
}
left = center;
center = right;
}
return row;
}
/**
* Identify where the end of the middle / payload section ends.
*
* @param row row of black/white values to search
* @return Array, containing index of start of 'end block' and end of 'end block'
* @throws NotFoundException
*/
int[] decodeEnd(BitArray row) throws NotFoundException {
// For convenience, reverse the row and then
// search from 'the start' for the end block
row.reverse();
try {
int endStart = skipWhiteSpace(row);
int[] endPattern = findGuardPattern(row, endStart, END_PATTERN_REVERSED);
// The start & end patterns must be pre/post fixed by a quiet zone. This
// zone must be at least 10 times the width of a narrow line.
// ref: http://www.barcode-1.net/i25code.html
validateQuietZone(row, endPattern[0]);
// Now recalculate the indices of where the 'endblock' starts & stops to
// accommodate
// the reversed nature of the search
int temp = endPattern[0];
endPattern[0] = row.getSize() - endPattern[1];
endPattern[1] = row.getSize() - temp;
return endPattern;
} finally {
// Put the row back the right way.
row.reverse();
}
}
/**
* Skip all whitespace until we get to the first black line.
*
* @param row row of black/white values to search
* @return index of the first black line.
* @throws NotFoundException Throws exception if no black lines are found in the row
*/
private static int skipWhiteSpace(BitArray row) throws NotFoundException {
int width = row.getSize();
int endStart = 0;
while (endStart < width) {
if (row.get(endStart)) {
break;
}
endStart++;
}
if (endStart == width) {
throw NotFoundException.getNotFoundInstance();
}
return endStart;
}
/**
* @param row row of black/white values to search
* @param rowOffset position to start search
* @param pattern pattern of counts of number of black and white pixels that are being searched
* for as a pattern
* @return start/end horizontal offset of guard pattern, as an array of two ints
* @throws NotFoundException if pattern is not found
*/
private static int[] findGuardPattern(BitArray row, int rowOffset, int[] pattern)
throws NotFoundException {
// TODO: This is very similar to implementation in UPCEANReader. Consider if they can be
// merged to a single method.
int patternLength = pattern.length;
int[] counters = new int[patternLength];
int width = row.getSize();
boolean isWhite = false;
int counterPosition = 0;
int patternStart = rowOffset;
for (int x = rowOffset; x < width; x++) {
boolean pixel = row.get(x);
if (pixel ^ isWhite) {
counters[counterPosition]++;
} else {
if (counterPosition == patternLength - 1) {
if (patternMatchVariance(counters, pattern, MAX_INDIVIDUAL_VARIANCE) < MAX_AVG_VARIANCE) {
return new int[] {patternStart, x};
}
patternStart += counters[0] + counters[1];
for (int y = 2; y < patternLength; y++) {
counters[y - 2] = counters[y];
}
counters[patternLength - 2] = 0;
counters[patternLength - 1] = 0;
counterPosition--;
} else {
counterPosition++;
}
counters[counterPosition] = 1;
isWhite = !isWhite;
}
}
throw NotFoundException.getNotFoundInstance();
}
