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Insert DIY steps making microscope webcam
=== Recognizing a plant in a pinch ===
by [[James Bryan Graves]]
 
When asked to assist how to quickly recognize a plant with a webcam I remember an Apple WWDC presentation called "Find my iCone" an app that tracked an orange construction pylon using it's color.
 
I already had some web/Javascript code to do some chromakey (greenscreen) swapping, so I just re-purposed it.  However, tracking the correct color of say "purple flowers" needed to be a little less fined grained then #ef0114 (for example, I have no idea what "color" that is by looking at it's hex values), so I grabbed a [http://chir.ag/projects/ntc/ JS library] to print colors as words.
 
Here's the code:
 
    <!DOCTYPE html>
    <html>
    <head>
      <script src="ntc.js"></script>
    </head>
    <body>
      <video id='v'></video>
      <h1>I don't see anything.</h1>
      <canvas id='c'></canvas>
    <script>
    function rgbToHex(r, g, b) {
        return "#" + ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).slice(1);
    }
   
    window.addEventListener('DOMContentLoaded', function() {
      var v = document.getElementById('v');
      navigator.getUserMedia = (
        navigator.getUserMedia ||
        navigator.webkitGetUserMedia ||
        navigator.mozGetUserMedia ||
        navigator.msGetUserMedia);
      if (navigator.getUserMedia) {
        // Request access to video only
        navigator.getUserMedia({
          video: true,
          audio: false
        }, function(stream) {
          var url = window.URL || window.webkitURL;
          v.src = url ? url.createObjectURL(stream) : stream;
          v.play();
        }, function(error) {
          alert('Something went wrong. (error code ' + error.code + ')');
          return;
        });
      } else {
        alert('Sorry, the browser you are using doesn\'t support getUserMedia');
        return;
      }
    });
   
    var isStreaming = false,
      v = document.getElementById('v'),
      c = document.getElementById('c'),
      //bg = document.getElementById('bg'),
      grey = document.getElementById('grey');
      con = c.getContext('2d');
      w = 480,
      h = 480,
      greyscale = false;
   
    v.addEventListener('canplay', function(e) {
      if (!isStreaming) {
        // videoWidth isn't always set correctly in all browsers
        if (v.videoWidth > 0) h = v.videoHeight / (v.videoWidth / w);
        c.setAttribute('width', w);
        c.setAttribute('height', h);
        // Reverse the canvas image
        con.translate(w, 0);
        con.scale(-1, 1);
        isStreaming = true;
      }
    }, false);
   
    v.addEventListener('play', function() {
      // Every 33 milliseconds copy the video image to the canvas
      setInterval(function() {
        if (v.paused || v.ended) return;
        con.fillRect(0, 0, w, h);
        con.drawImage(v, 0, 0, w, h);
        //goingGrey();
        chromaKey();
      }, 33);
    }, false);
   
    var goingGrey = function() {
      var imageData = con.getImageData(0, 0, w, h);
      var data = imageData.data;
      for (var i = 0; i < data.length; i += 4) {
        var bright = 0.34 * data[i] + 0.5 * data[i + 1] + 0.16 * data[i + 2];
        data[i] = bright;
        data[i + 1] = bright;
        data[i + 2] = bright;
      }
      con.putImageData(imageData, 0, 0);
    };
   
    var count = 0;
    var purpleCount = 0;
    var chromaKey = function() {
      var camData = con.getImageData(0, 0, w, h);
      //con.drawImage(bg, 0, 0, w, h);
      var bgData = con.getImageData(0, 0, w, h);
      var imgData = con.createImageData(w, h);
      document.querySelector('h1').innerHTML = 'I see nothing.';
   
      for (i = 0; i < imgData.width * imgData.height * 4; i += 4) {
        var r = camData.data[i + 0];
        var g = camData.data[i + 1];
        var b = camData.data[i + 2];
        var a = camData.data[i + 3];
   
   
        if(++count % 200 == 0) {
          var hexColor = rgbToHex(r,g,b);
   
          var n_match  = ntc.name(hexColor);
          n_rgb        = n_match[0]; // RGB value of closest match
          n_name      = n_match[1]; // Text string: Color name
          n_exactmatch = n_match[2]; // True if exact color match
       
          // compare rgb levels for green and set alphachannel to 0;
          if (n_name.indexOf('Loulou') != -1) {
            console.log(n_name);
            console.log(hexColor);
            if(++purpleCount > 100) {
              document.querySelector('h1').innerHTML = 'I see the plant.';
              imgData.data[i + 0] = 0;
              imgData.data[i + 1] = 0;
              imgData.data[i + 2] = 0;
              imgData.data[i + 3] = 1;   
            }
          } else {
            imgData.data[i + 0] = r;
            imgData.data[i + 1] = g;
            imgData.data[i + 2] = b;
            imgData.data[i + 3] = a;
          }
        }
      }
      con.putImageData(imgData, 0, 0);
    };
   
    </script>
    </body>
    </html>
 


[[Category:DIY Manual]]
[[Category:DIY Manual]]

Revision as of 16:03, 22 November 2015

Recognizing a plant in a pinch

by James Bryan Graves

When asked to assist how to quickly recognize a plant with a webcam I remember an Apple WWDC presentation called "Find my iCone" an app that tracked an orange construction pylon using it's color.

I already had some web/Javascript code to do some chromakey (greenscreen) swapping, so I just re-purposed it. However, tracking the correct color of say "purple flowers" needed to be a little less fined grained then #ef0114 (for example, I have no idea what "color" that is by looking at it's hex values), so I grabbed a JS library to print colors as words.

Here's the code: 

   <!DOCTYPE html>
   
    
        
    
    
      
      
I don't see anything.
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