Barcode detection by webcam.

I'm using 2013a version and i have a project which uses webcam to read barcode. My functions are based on a demo of Matlab vision, how could i read and decode through webcam directly, not using "getsnapshot"? I'm sorry for my bad grammar. Here is my code:

obj = videoinput('winvideo', 2,'YUY2_640x480'); 
set(obj,'ReturnedColorSpace','rgb'); 
src_obj = getselectedsource(obj); 
get(src_obj); 
vidRes = get(obj, 'VideoResolution'); 
nBands = get(obj, 'NumberOfBands'); 
hImage = image( zeros(vidRes(2), vidRes(1), nBands) );  

FinalCode1=0;

while (1)
    ip_im = getsnapshot(obj);
    imshow(ip_im);

      %filter
      fi_im=imsharpen(ip_im);

      % Convert from RGB to Gray
      gray_im= rgb2gray(fi_im);

      %1
      %Threshold Image to black and white
      J = im2bw(gray_im, graythresh(gray_im));

      %Resize and process
      J=imresize(J,[240 320]);
      Row = [80 120 160]';
      [R,F] = Feature(J, Row);

      [Center, Width, Num] = Bar(F);

      [Sequence, Num] = Detection(Width, Num, 2);

      [LGCode, LCode, GCode, RCode, LCodeRev, GCodeRev, RCodeRev] = Codebook;

      [Code, Conf] = Recognition(Center, Width, Sequence, Num, LGCode, LCode, GCode, RCode, LCodeRev, GCodeRev, RCodeRev);

      %Validation
      OddSum= Code(1:1)+Code(3:3)+Code(5:5)+Code(7:7)+Code(9:9)+Code(11:11)+Code(13:13);
      EvenSum = Code(2:2)+Code(4:4)+Code(6:6)+Code(8:8)+Code(10:10)+Code(12:12);

      Checksums = OddSum + 3*EvenSum;

      Valid = and((not(mod(Checksums,10))),(Conf >= 0.7));

      FinalCode=uint64(0);
      for i = 1 :13
          FinalCode=FinalCode*10 + uint64(Code(i:i));
      end
      if and(Valid ,(FinalCode ~= FinalCode1))
          Code'
          sprintf('%013i',FinalCode)
          FinalCode1 = FinalCode';
      end

end

Answer 1

[Walter Roberson]

If you were using R2014a or later, instead of using getsnapshot() from the Image Acquisition Toolbox, you could use snapshot() from the USB Webcams support package.

The general purpose of getsnapshot() and snapshot() are the same: they obtain a single frame from the video feed so that the frame can be analyzed.

You can see snapshot() being used in this Computer Vision demo

[Duc Do Minh]

Thank you very much! but Does "snapshot()" trigger or delay video output display? I want to make a live analysis and show the video through a figure and barcode is detected and encode in background, only the result can be showed in the figure or the code is showed in Command Window.

[Walter Roberson]

snapshot() does not trigger or delay video output. If you are using the Computer Vision toolbox you can create whatever output image you want and then step() the array with a videoplayer object to have the image displayed.