Hi, I am doing a project on reading qr code using processing. I have tried using logitech web camera C310 (windows 7) and the laptop webcam for example qrcode and bar code but it does not detect the qr code although I already snap it. How can I solve this problem?
It states that Error: Invalid number of Finder Pattern detected.
Can I ask you to be more specific? For instance
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Please provide the code you are using for this task as well as your testing image.
Kf
Sorry for that. Ok, Iām using the QRCode 0.3a by Daniel Shiffman and [Zxing For Processing (barcode library)]
[Rolf van Gelder] examples. Iām using processing 3.4
The code for the QRcode example is:
/*
QRcode reader
Generate images from a QRcode generator such as
http://qrcode.kaywa.com/ and put them in this sketch's
data folder.
Press spacebar to read from the camera, generate an image,
and scan for barcodes. Press f to read from a file and scan.
Press s for camera settings.
Created 9 June 2007
by Tom Igoe / Daniel Shiffman
*/
import processing.video.*;
import qrcodeprocessing.*;
Capture video; // instance of the video capture library
String statusMsg = "Waiting for an image"; // a string to return messages:
// Decoder object from prdecoder library
Decoder decoder;
void setup() {
size(400, 320);
video = new Capture(this, 320, 240);
video.start();
// Create a decoder object
decoder = new Decoder(this);
}
// When the decoder object finishes
// this method will be invoked.
void decoderEvent(Decoder decoder) {
statusMsg = decoder.getDecodedString();
}
void captureEvent(Capture video) {
video.read();
}
void draw() {
background(0);
// Display video
image(video, 0, 0);
// Display status
text(statusMsg, 10, height-4);
// If we are currently decoding
if (decoder.decoding()) {
// Display the image being decoded
PImage show = decoder.getImage();
image(show, 0, 0, show.width/4, show.height/4);
statusMsg = "Decoding image";
for (int i = 0; i < (frameCount/2) % 10; i++) statusMsg += ".";
}
}
void keyReleased() {
// Depending on which key is hit, do different things:
switch (key) {
case ' ':
// Spacebar takes a picture and tests it:
// copy it to the PImage savedFrame:
PImage savedFrame = createImage(video.width, video.height, RGB);
savedFrame.copy(video, 0, 0, video.width, video.height, 0, 0, video.width, video.height);
savedFrame.updatePixels();
// Decode savedFrame
decoder.decodeImage(savedFrame);
break;
case 'f': // f runs a test on a file
PImage preservedFrame = loadImage("qrcode.png");
// Decode file
decoder.decodeImage(preservedFrame);
break;
}
}
The barcode reader cam from the zxing library is:
/*****************************************************************************
*
* barcodeReaderCam - v07/26/2018
*
* An example of the use of the ZXING4P.barcodeReader() method.
*
* Opens a webcam and tries to find barcodes in the image.
*
* You can define for which barcode types it will scan.
* Per default it looks for all available types.
*
* When a barcode is detected it will display the decoded text.
*
* Run this sketch and hold a printed copy of a barcode in front of the cam.
*
* Note: make sure your video image is NOT mirrored! It won't detect QRCodes
* that way...
*
* Library page:
* http://cagewebdev.com/zxing4processing-processing-library/
*
* (c) 2013-2018 Rolf van Gelder, http://cagewebdev.com, http://rvg.cage.nl
*
*****************************************************************************/
// IMPORT THE ZXING4PROCESSING LIBRARY AND DECLARE A ZXING4P OBJECT
import com.cage.zxing4p3.*;
ZXING4P zxing4p;
// PROCESSING VIDEO LIBRARY
import processing.video.*;
Capture video;
// PIMAGE WITH THE BARCODES TO DETECT
PImage scanArea;
// TEXT THAT WAS FOUND
String decodedText;
String latestDecodedText = "";
// FORMAT OF THE LATEST FOUND BARCODE
String barcodeFormat = "";
int txtWidth;
// FOR THE VIEW FINDER AND SCAN AREA
int frameWidth = 240;
int frameHeight = 260;
int lineSize = 40;
// CORNERS OF THE VIEW FINDER
PVector ul, ur, ll, lr;
// LIST WITH BARCODE TYPES TO LOOK FOR
ArrayList<String> barcodeTypes = new ArrayList<String>();
/*****************************************************************************
*
* SETUP
*
*****************************************************************************/
void setup() {
size(640, 480);
// LAYOUT
textAlign(CENTER);
textSize(30);
// CREATE CAPTURE
video = new Capture(this, width, height);
// START CAPTURING
video.start();
// CREATE A NEW EN-/DECODER INSTANCE
zxing4p = new ZXING4P();
// DISPLAY VERSION INFORMATION
zxing4p.version();
// UPPER LEFT CORNER OF THE VIEW FINDER
ul = new PVector((width - frameWidth) >> 1, (height - frameHeight) >> 1);
// UPPER RIGHT CORNER OF THE VIEW FINDER
ur = new PVector(ul.x + frameWidth, ul.y);
// LOWER LEFT CORNER OF THE VIEW FINDER
ll = new PVector(ul.x, ul.y + frameHeight);
// LOWER RIGHT CORNER OF THE VIEW FINDER
lr = new PVector(ur.x, ur.y + frameHeight);
// AREA TO SCAN
scanArea = createImage(frameWidth, frameHeight, RGB);
// BARCODE TYPES THAT WILL BE SCANNED FOR
// SUPPORTED BARCODE TYPES:
// AZTEC
// CODABAR
// CODE_128
// CODE_39
// CODE_93
// DATA_MATRIX
// EAN_13
// EAN_8
// ITF
// MAXICODE
// PDF_417
// QR_CODE
// RSS_14
// RSS_EXPANDED
// UPC_A
// UPC_E
// UPC_EAN_EXTENSION
barcodeTypes.add("EAN_8");
barcodeTypes.add("EAN_13");
barcodeTypes.add("DATA_MATRIX");
barcodeTypes.add("QR_CODE");
} // setup()
/*****************************************************************************
*
* DRAW
*
*****************************************************************************/
void draw() {
background(0);
// UPDATE CAPTURE
if (video.available()) video.read();
// DISPLAY VIDEO CAPTURE
set(0, 0, video);
if (frameCount % 50 == 0) {
// COPY THE VIEW FINDER AREA TO THE SCAN AREA
scanArea.copy(video, (int)ul.x, (int)ul.y, frameWidth, frameHeight, 0, 0, frameWidth, frameHeight);
}
// DISPLAY VIEW FINDER
pushStyle();
noFill();
strokeWeight(4);
stroke(255, 0, 0);
line(ul.x, ul.y, ul.x + lineSize, ul.y);
line(ul.x, ul.y, ul.x, ul.y + lineSize);
line(ur.x - lineSize, ur.y, ur.x, ur.y);
line(ur.x, ur.y, ur.x, ur.y + lineSize);
line(ll.x, ll.y, ll.x + lineSize, ll.y);
line(ll.x, ll.y - lineSize, ll.x, ll.y);
line(lr.x - lineSize, lr.y, lr.x, lr.y);
line(lr.x, lr.y - lineSize, lr.x, lr.y);
popStyle();
// DISPLAY LATEST DECODED TEXT AND FORMAT
if (!latestDecodedText.equals("")) {
pushStyle();
txtWidth = int(textWidth(latestDecodedText + " (" + barcodeFormat + ")"));
fill(0, 150);
rect((width>>1) - (txtWidth>>1) - 5, 15, txtWidth + 10, 36);
fill(255, 255, 0);
text(latestDecodedText + " (" + barcodeFormat + ")", width>>1, 43);
popStyle();
} // if (!latestDecodedText.equals(""))
// TRY TO DETECT AND DECODE A QRCODE IN THE VIDEO CAPTURE
// multiFormatReader(PImage img, boolean tryHarder)
// multiFormatReader(PImage img, boolean tryHarder, ArrayList<String> barcodeTypes)
// img: image to scan for barcodes
// tryHarder: false => fast detection (less accurate)
// true => best detection (little slower)
// barcodeTypes: barcode types to scan for
try {
// SCAN FOR ALL AVAILABLE BARCODE TYPES
//decodedText = zxing4p.barcodeReader(scanArea, false);
// SCAN FOR SPECIFIC BARCODE TYPES
decodedText = zxing4p.barcodeReader(scanArea, false, barcodeTypes);
// GET THE TYPE OF THE LAST SCANNED BARCODE
barcodeFormat = zxing4p.getBarcodeFormat();
}
catch (Exception e) {
// NOT FOUND
decodedText = "";
} // try
if (!decodedText.equals("")) {
// FOUND A BARCODE!
if (latestDecodedText.equals("") || (!latestDecodedText.equals(decodedText))) {
println("Zxing4processing detected: " + decodedText + " (" + barcodeFormat + ")");
}
latestDecodedText = decodedText;
} // if (!decodedText.equals(""))
} // draw()
/*****************************************************************************
*
* KEYBOARD HANDLER
*
*****************************************************************************/
void keyPressed() {
switch(key) {
case ' ':
// RESET
decodedText = "";
latestDecodedText = "";
break;
} // switch
} // keyPressed()
For the QR code example I press the spacebar to snap the image of the QR code from printed as attached below then the error shown. For the barcode example I didnāt press anything and just show any barcode on books and it donāt read them. Iām new to the qr code and bar code processing. I just try them based on what I googled.
All the libraries that I added from the contribution manager is:
AP-Sync peace Nigel Tiany
AndroidCapture for Processing 2.0 JianbinQi
Arduino (Firmata) 9 David A. Mellis
GL Video 1.2.3 Gottfried Haider
Image processing algorithms 1.3.0 Nick āMilchreisā MĆ¼ller
IPCapture 0.4.2 Stefano āsingintimeā Baldan
meter 1.0c Bill (Papa) Kujawa
QRCode 0.3a Daniel Shiffman
Syphon 2.0 Andres Colubri
Video 1.0.1 The Processing Foundation
Video Export 0.2.3 Abe Pazos
VSync for Processing v0.1 Maximilian Ernestus
Zxing For Processing (barcode library) 3.5 Rolf van Gelder
The code that you show looks good; Daniel and Tom are great programmers.
You probably need to check your configuration, and set the right environment.
All that you need are the libraries:
Use this for ZXING:
https://repo1.maven.org/maven2/com/google/zxing/core/3.3.2/
You can use the processingās āadd library toolā
Iām using : java version ā1.8.0_191ā
and Processing: 3.4
Ā”Good luck! 
āWhen in doubt, use brute forceā.
ā [Ken Thompson](http://genius.cat-v.org/ken-thompson/)