js-zxing-pdf417
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PeculiarVentures
Not decoding PDF417 , don't seem to find start pattern
Hi,
I have barcode that don't seem to decode, I tried to figure out what the issue is and think its the start pattern that is not correct. There few other sites that is able to decode the barcode, so I know it can be done and I also know the barcode is not 100% according to specs.
Possible you can look at the barcode or maybe give me hint on how I can troubleshoot why start pattern not recognized.. I attach sample
Hi @liaan, would you mind add some links to the websites that were able to decode the barcode? Thanks, P.
https://online-barcode-reader.inliteresearch.com/ https://demo.dynamsoft.com/dbr/barcodereaderdemo.aspx
pattern [8, 1, 2, 1, 1, 1, 1, 3] seems to match, but don't have time now to figure why not decoding ..
Ok, dropped the MAX_INDIVIDUAL_VARIANCE to 160 .. , seem to decode now with above change .. I will have to test few more barcodes .. seems like the very poorly printed
@rmhrisk Not 100% sure , I;m just tasked with making a function to take a uploaded image of the license disk and decode it so string so string can be passed onto another API for decoding ... problem is, the pdf on license disk don't comply to standard (or very badly printed) so need adjust script to work around it.
ok ... not working with other barcodes. Its giving to many error in errorcorrection. will look into this other time
Though we believe it is possible to make the necessary improvements to be more accommodating of malformed and low resolution barcodes right now, as a port of the Xing PDF417 functionality, it is fairly picky. Do let us know if you make improvements, we would be glad to take them.
@rmhrisk
Ok, made progress .. its reads the first row 100%.
The next row the values are stored, but rownumber is -1 .. I will debug some more later
Sounds to me like image quality is fine, it must be ratio thing or something... will decode more later
Pic of first codeword in second row.
Ok ... just because i'm debugging Here the results from zxing vs Inlite .. now to go figure out why its reading first few columns correct and then loosing the plot :)
Inlite:
\620\924\002\621\590\195\084\230\674\501\046\207\358\137\766\263\277\189\631\243\081\402
\396\327\328\517\182\286\879\674\744\858\200\843\365\442\575\308\759\352\082\486\141\212
\036\824\213\247\414\462\134\406\420\596\522\789\035\017\013\289\029\451\249\704\255\140
\776\148\566\564\037\387\424\050\549\404\418\305\781\396\738\111\396\736\743\197\761\241
\567\667\169\548\015\593\637\525\476\117\732\387\746\389\378\003\705\431\121\380\082\799
\635\093\332\547\231\764\681\140\849\742\527\884\228\247\533\489\353\364\094\378\466\089
\249\744\457\694\872\303\434\221\808\182\328\768\652\837\666\161\670\850\370\265\129\109
\744\590\354\097\840\483\820\003\279\160\790\897\151\338\756\189\407\167\232\415\490\378
\201\249\195\704\821\584\126\707\716\450\347\030\018\258\556\100\409\789\884\316\295\137
\151\310\311\503\170\783\435\792\740\230\571\695\211\243\198\091\496\449\756\197\698\620
\778\335\186\667\372\299\339\075\634\634\490\173\413\580\305\878\280\353\733\162\738\812
\186\219\487\538\477\417\870\665\544\502\393\016\843\281\507\328\250\512\522\442\088\260
\785\327\467\219\717\506\539\558\109\182\727\641\006\302\650\779\327\173\080\478\150\506
\589\007\800\763\652\637\018\694\365\121\274\131\733\860\546\570\330\144\588\265\573\002
\889\505\329\898\156\032\091\411\747\274\547\338\685\387\044\163\259\504\154\289\006\015
\395\515\285\696\517\742\089\183\422\410\176\124\203\028\766\771\804\301\061\657\799\435
\253\298\666\028\402\131\331\443\128\443\080\531\539\551\489\331\159\782\788\608\167\353
\015\266\278\015\116\799\678\398\182\268\704\544\653\396\734\137\146\427\351\790\546\686
\864\134\536\113\725\475\388\662\842\339\324\392\371\181\217\726\338\652\890\104\564\388
\853\620\680\666\426\847\189\132\599\159\234\767\713\862\193\334\595\266\754\372\604\740
\224\333\315\266\073\424\481\219\267\180\534\131\050\632\855\020\674\132\398\096\821\299
\399\119\155\357\358\199\845\844\364\675\122\792\113\104\526\232\442\729\613\585\413\842
\044\511\519\189\034\001\887\829\312\689\818\803\488\038\410\109\128\759\132\413\605\662
\837\008\254\752\242\047\081\113\658\176\898\099\534\404\782\344\360\015\769\784\604\337
\679\324\229\356\364\611\698\327\000\320\018\227\178\633\196\023\499\664\631\157\036\850
\684\762\327\628\263\018\591\189\374\358\127\319\156\036\596\719\464\352\008\063\198\559
\078\779\434\876\314\306\666\221\172\188\393\116\843\851\559\002\060\594\882\489\066\101
\884\732\473\130\088\371\202\524\900\900\900\900\900\900\900\900\900\900\900\900\900\900
\900\900\900\900\023\179\776\333\599\390\846\507\183\889\503\853\016\036\476\862\821\249
\135\120\107\043\737\755\776\369\902\223\130\799\407\076\311\311\601\513\472\516\020\802
\066\161\114\141\186\219\691\599\382\295\285\349\005\623\218\468\053\025\489\888\354\768
\184\417\917\520\333\274\205\395\791\050\186\764\194\182\111\418\119\126\706\470\256\534
\388\353\840\614\450\037\571\055\688\109\338\157\324\211\922\366\100\913\878\786\870\158
\431\760\309\607\289\366\495\078\325\737\418\882\021\517\220\881\263\567\545\369\136\800
Zxing JS
\620\924\002\621\590\195\084\230\000\501\000\207\358\137\766\000\000\841\778\000\402\000
\396\327\328\517\182\286\879\674\744\858\200\000\365\000\575\308\000\719\082\000\860\000
\036\824\213\247\414\462\134\406\420\596\522\789\035\000\013\289\000\451\249\000\000\676
\776\148\566\564\037\387\424\050\549\404\418\305\781\396\738\111\000\000\000\579\493\000
\567\667\169\548\015\593\637\525\476\117\732\387\000\389\378\003\000\000\121\380\082\000
\635\093\332\547\231\764\681\140\849\742\527\884\228\247\533\489\353\364\094\378\466\000
\249\744\457\694\872\303\434\221\808\182\328\768\652\837\666\161\670\850\370\000\129\000
\744\590\354\097\840\483\820\003\279\160\790\897\151\338\756\189\590\167\232\415\490\000
\201\249\195\704\821\584\126\707\716\450\467\030\018\268\556\100\514\789\884\316\000\137
\151\310\311\503\170\783\435\792\740\230\571\000\000\339\198\091\730\000\717\243\000\123
\778\335\186\667\372\299\339\075\634\634\490\173\413\580\305\878\280\353\733\162\738\812
\186\219\487\538\477\417\870\665\544\502\393\016\843\281\507\328\250\512\522\442\000\260
\785\327\467\219\717\348\838\685\746\112\239\351\093\636\793\764\685\000\000\000\669\333
\589\007\800\763\652\637\018\694\365\121\274\131\733\860\546\570\330\144\588\265\573\002
\889\505\329\898\156\032\091\411\747\274\547\338\685\387\044\163\754\709\000\837\912\856
\395\515\285\696\517\742\089\183\422\410\176\124\203\028\766\771\804\301\061\657\799\435
\253\298\666\028\402\131\331\443\128\443\080\531\539\551\489\331\159\782\788\608\167\353
\015\266\278\015\116\799\678\398\182\268\704\544\653\396\734\137\146\427\351\790\000\686
\864\134\536\113\725\475\388\662\842\339\324\392\371\181\217\726\338\652\890\104\564\000
\853\620\680\666\426\847\189\132\599\159\234\767\713\862\000\000\000\034\000\604\740\000
\224\333\315\266\073\424\481\219\267\180\534\131\050\632\855\020\674\132\398\096\000\299
\399\119\155\357\358\199\845\844\364\675\122\792\113\104\526\232\442\729\613\585\413\842
\044\511\519\189\034\001\887\829\312\689\818\803\488\038\410\109\128\759\132\413\000\662
\837\008\254\752\242\047\081\113\658\176\898\099\534\404\782\344\360\015\769\784\000\000
\679\324\229\356\364\611\698\327\000\320\018\227\178\000\196\000\499\000\000\928\000\442
\684\762\327\628\263\018\591\189\374\358\127\319\156\036\596\719\464\352\008\063\000\559
\078\779\434\876\314\306\666\221\172\188\393\116\843\851\559\002\060\594\882\489\066\101
\884\732\473\130\088\371\202\524\900\900\900\900\900\900\900\900\000\000\667\667\667\900
\900\900\900\900\023\179\776\333\599\390\846\507\183\889\503\000\016\036\476\028\821\000
\135\120\107\043\737\755\776\369\902\223\130\799\407\076\311\311\601\513\000\516\020\802
\066\161\114\141\186\219\691\599\382\295\285\349\005\623\218\468\053\025\489\888\212\000
\184\417\917\520\333\274\205\395\791\050\186\000\194\182\111\206\899\000\000\000\000\856
\388\353\840\614\450\037\571\055\688\109\338\157\324\211\922\366\100\913\878\786\870\158
\431\760\309\607\289\366\495\078\325\737\647\882\021\517\220\881\263\000\000\000\000\000
Image used:
@rmhrisk Any idea what ZXing.PDF417.Internal.PDF417ScanningDecoder.CODEWORD_SKEW_SIZE does ? I thought its the skewness of the row and bigger allow more skew? Reason, changed it to 1 now and decodes barcode better....
Found another issue ..... shift right (>>) in JS only support 32 bit .. so decodedBytes.push((value >> (8 * (5 - j1)))); drops the first bits and corrupts data. Busy reworking code to make it work
so following line don't work as expected: decodedBytes.push((value >> (8 * (5 - j1)))); easy test:
var bla = 0b11001101100001001010001010000111100000001
for(i=0; i <40;i++){
console.log('bla',bla.toString(2),'i',i,'shifted',((bla >> i)).toString(2));
Output
bla 11001101100001001010001010000111100000001 i 0 shifted 1001010001010000111100000001
bla 11001101100001001010001010000111100000001 i 1 shifted 100101000101000011110000000
bla 11001101100001001010001010000111100000001 i 2 shifted 10010100010100001111000000
bla 11001101100001001010001010000111100000001 i 3 shifted 1001010001010000111100000
bla 11001101100001001010001010000111100000001 i 4 shifted 100101000101000011110000
bla 11001101100001001010001010000111100000001 i 5 shifted 10010100010100001111000
bla 11001101100001001010001010000111100000001 i 6 shifted 1001010001010000111100
bla 11001101100001001010001010000111100000001 i 7 shifted 100101000101000011110
bla 11001101100001001010001010000111100000001 i 8 shifted 10010100010100001111
bla 11001101100001001010001010000111100000001 i 9 shifted 1001010001010000111
bla 11001101100001001010001010000111100000001 i 10 shifted 100101000101000011
bla 11001101100001001010001010000111100000001 i 11 shifted 10010100010100001
bla 11001101100001001010001010000111100000001 i 12 shifted 1001010001010000
bla 11001101100001001010001010000111100000001 i 13 shifted 100101000101000
bla 11001101100001001010001010000111100000001 i 14 shifted 10010100010100
bla 11001101100001001010001010000111100000001 i 15 shifted 1001010001010
bla 11001101100001001010001010000111100000001 i 16 shifted 100101000101
bla 11001101100001001010001010000111100000001 i 17 shifted 10010100010
bla 11001101100001001010001010000111100000001 i 18 shifted 1001010001
bla 11001101100001001010001010000111100000001 i 19 shifted 100101000
bla 11001101100001001010001010000111100000001 i 20 shifted 10010100
bla 11001101100001001010001010000111100000001 i 21 shifted 1001010
bla 11001101100001001010001010000111100000001 i 22 shifted 100101
bla 11001101100001001010001010000111100000001 i 23 shifted 10010
bla 11001101100001001010001010000111100000001 i 24 shifted 1001
bla 11001101100001001010001010000111100000001 i 25 shifted 100
bla 11001101100001001010001010000111100000001 i 26 shifted 10
bla 11001101100001001010001010000111100000001 i 27 shifted 1
bla 11001101100001001010001010000111100000001 i 28 shifted 0
bla 11001101100001001010001010000111100000001 i 29 shifted 0
bla 11001101100001001010001010000111100000001 i 30 shifted 0
bla 11001101100001001010001010000111100000001 i 31 shifted 0
bla 11001101100001001010001010000111100000001 i 32 shifted 1001010001010000111100000001
bla 11001101100001001010001010000111100000001 i 33 shifted 100101000101000011110000000
bla 11001101100001001010001010000111100000001 i 34 shifted 10010100010100001111000000
bla 11001101100001001010001010000111100000001 i 35 shifted 1001010001010000111100000
bla 11001101100001001010001010000111100000001 i 36 shifted 100101000101000011110000
bla 11001101100001001010001010000111100000001 i 37 shifted 10010100010100001111000
bla 11001101100001001010001010000111100000001 i 38 shifted 1001010001010000111100
bla 11001101100001001010001010000111100000001 i 39 shifted 100101000101000011110
Just a hint: ByteStream.js has class BitStream which supports right and left shifting for unlimited data.
Just a hint: ByteStream.js has class BitStream which supports right and left shifting for unlimited data.
Thanks ... trying to use BigInteger's shiftRight function seeing its already included.
seems to work with this
ZXing.PDF417.Internal.DecodedBitStreamParser.byteCompaction = function (p) {
var mode = p.mode, codewords = p.codewords, codeIndex = p.codeIndex;
var decodedBytes = [];
var count = 0;
//var value = 0;
var value = new bigInt(0);
//console.log('new value',value.shiftRight(1).toString(2));
var end = false;
if (mode == 901) {
count = 0;
value =bigInt(0);
var byteCompactedCodewords = new Int32Array(6);
end = false;
var nextCode = codewords[codeIndex++];
while ((codeIndex < codewords[0]) && !end) {
byteCompactedCodewords[count++] = nextCode;
// value = 900 * value + nextCode;
value = bigInt(900 * value + nextCode);
nextCode = codewords[codeIndex++];
if (nextCode == 900 || nextCode == 901 || nextCode == 902 || nextCode == 924 || nextCode == 928 || nextCode == 923 || nextCode == 922) {
codeIndex--;
end = true;
}
else {
if ((count % 5 === 0) && (count > 0)) {
for (var j = 0; j < 6; ++j) {
decodedBytes.push((value >> (8 * (5 - j))));
}
value = 0;
count = 0;
}
}
}
if (codeIndex == codewords[0] && nextCode < 900)
byteCompactedCodewords[count++] = nextCode;
for (var i = 0; i < count; i++) {
decodedBytes.push(byteCompactedCodewords[i]);
}
} else if (mode == 924) {
count = 0;
value = bigInt(0);
end = false;
while (codeIndex < codewords[0] && !end) {
var code = codewords[codeIndex++];
if (code < 900) {
count++;
value = bigInt(900 * value + code);
// console.log('val2',value)
//console.log('code',code)
}
else {
if (code == 900 || code == 901 || code == 902 || code == 924 || code == 928 || code == 923 || code == 922) {
codeIndex--;
end = true;
}
}
if ((count % 5 == 0) && (count > 0)) {
for (var j1 = 0; j1 < 6; ++j1) {
// value.shiftRight(6)
decodedBytes.push((value.shiftRight(8 * (5 - j1))));
//console.log(typeof value.shiftRight(5))
//console.log('values',value, '', 8 * (5 - j1),(value >> (8 * (5 - j1))));
}
//console.log('val',value)
value = 0;
count = 0;
}
}
}
//console.log('bla',String.fromCharCode.apply(null, decodedBytes))
p.result += (String.fromCharCode.apply(null, decodedBytes));
return codeIndex;
};
@liaan do I understand correctly you think you found what the core issue was and are now able to use the library for your use case?
@rmhrisk Any idea what ZXing.PDF417.Internal.PDF417ScanningDecoder.CODEWORD_SKEW_SIZE does ? I thought its the skewness of the row and bigger allow more skew? Reason, changed it to 1 now and decodes barcode better....
@patriziobruno can you explain?
@liaan do I understand correctly you think you found what the core issue was and are now able to use the library for your use case?
Well .. it decodes the barcode .. but only 80% of data is correct, rest is wrong. I would have thought with 6x error correction it would be 100% correct. So either the error correction code is buggy or there even more typo's in code.
I will spend more time on it at some point
@rmhrisk, @liaan is right that's the max threshold for the "skewness"
@liaan - Did you manage to get this working for the South African Drivers license?
@liaan - Did you manage to get this working for the South African Drivers license?
Morning, No, the library don't follow PDF417 standards correctley and simply don't have time to fix all the problems. I got it to scan most of the ID's but the error detection/redundancy part of the library seems to be very buggy so never produce correct output unless its 100% correctley scanned, it does not fix problems as it should (PDF417 have >6 times redundancy).
@liaan if you do have fixes we would love to have them, we will find time to get back to this library again in the not so distant future.
seems to work with this
ZXing.PDF417.Internal.DecodedBitStreamParser.byteCompaction = function (p) { var mode = p.mode, codewords = p.codewords, codeIndex = p.codeIndex; var decodedBytes = []; var count = 0; //var value = 0; var value = new bigInt(0); //console.log('new value',value.shiftRight(1).toString(2)); var end = false; if (mode == 901) { count = 0; value =bigInt(0); var byteCompactedCodewords = new Int32Array(6); end = false; var nextCode = codewords[codeIndex++]; while ((codeIndex < codewords[0]) && !end) { byteCompactedCodewords[count++] = nextCode; // value = 900 * value + nextCode; value = bigInt(900 * value + nextCode); nextCode = codewords[codeIndex++]; if (nextCode == 900 || nextCode == 901 || nextCode == 902 || nextCode == 924 || nextCode == 928 || nextCode == 923 || nextCode == 922) { codeIndex--; end = true; } else { if ((count % 5 === 0) && (count > 0)) { for (var j = 0; j < 6; ++j) { decodedBytes.push((value >> (8 * (5 - j)))); } value = 0; count = 0; } } } if (codeIndex == codewords[0] && nextCode < 900) byteCompactedCodewords[count++] = nextCode; for (var i = 0; i < count; i++) { decodedBytes.push(byteCompactedCodewords[i]); } } else if (mode == 924) { count = 0; value = bigInt(0); end = false; while (codeIndex < codewords[0] && !end) { var code = codewords[codeIndex++]; if (code < 900) { count++; value = bigInt(900 * value + code); // console.log('val2',value) //console.log('code',code) } else { if (code == 900 || code == 901 || code == 902 || code == 924 || code == 928 || code == 923 || code == 922) { codeIndex--; end = true; } } if ((count % 5 == 0) && (count > 0)) { for (var j1 = 0; j1 < 6; ++j1) { // value.shiftRight(6) decodedBytes.push((value.shiftRight(8 * (5 - j1)))); //console.log(typeof value.shiftRight(5)) //console.log('values',value, '', 8 * (5 - j1),(value >> (8 * (5 - j1)))); } //console.log('val',value) value = 0; count = 0; } } } //console.log('bla',String.fromCharCode.apply(null, decodedBytes)) p.result += (String.fromCharCode.apply(null, decodedBytes)); return codeIndex; };
I have got the same codewords as inlite returns but after that, ByteCompaction return decodedbytes with values 1, 411, 105225, 26937669, 1765387075584 for initial codewords and then
p.result += (String.fromCharCode.apply(null, decodedBytes));
the above line returns
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