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POChromakey'd HTML webcam wont save with transparancy
 

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  1. POChromakey'd HTML webcam wont save with transparancy
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    <p>I have set up a green screen with a webcam, HTML5 video and canvas. I took an idea from MDN on creating a chroma key (green screen). But with a live webcam instead of a prerecorded video. Everything works as expected except when I go to save the image, the chroma key area is white instead of transparent. There is a background of the ocean. When the webcam is on and a person is standing in front of it, it looks like the person is in the ocean. Again, saving that image just gives me a white box with myself in the middle of it. The webcam dimensions are 640 x 480 and the canvas dimensions are 1600 x 800. </p> <p><strong>Edit:</strong> I changed the chroma key tolerance to be anything dark greyish and above. Now if you put something white in front of your camera, it should, in theory, show the entire background image. But its left with a 640x480 box the same color as the <code>&lt;body&gt;</code>.</p> <p><a href="http://cultofpoopsy.net/cam/booth.html" rel="nofollow">Here is a demo</a> Doesn't really work unless you have some green in the background. Webkit only.</p> <p>Webcam chroma key:</p> <pre><code>var processor = { timerCallback: function() { if (this.webcam.paused || this.webcam.ended) { return; } this.computeFrame(); var self = this; setTimeout(function () { self.timerCallback(); }, 0); }, doLoad: function() { this.webcam = document.getElementById("webcam"); this.c1 = document.getElementById("c1"); this.ctx1 = this.c1.getContext("2d"); this.c2 = document.getElementById("c2"); this.ctx2 = this.c2.getContext("2d"); var self = this; this.webcam.addEventListener("play", function() { self.width = 640; self.height = 480; self.timerCallback(); }, false); }, computeFrame: function() { this.ctx1.drawImage(this.webcam, 0, 0, 640, 480); //draw webcam to canvas var frame = this.ctx1.getImageData(0, 0, 640, 480); //capture a frame var l = frame.data.length / 4; for (var i = 0; i &lt; l; i++) { //loop through pixels var r = frame.data[i * 4 + 0]; var g = frame.data[i * 4 + 1]; var b = frame.data[i * 4 + 2]; if (g &gt; 100 &amp;&amp; r &lt; 95 &amp;&amp; b &gt; 60 &amp;&amp; b &lt; 160 ){ frame.data[i * 4 + 3] = 0; } } this.ctx2.putImageData(frame, 480, 300); //place chroma video over bg img return; } }; </code></pre> <p>script.js</p> <pre><code>processor.doLoad(); //more stuff runs takePicture(); function takepicture() { var canv = document.getElementById('c2'); var photo = document.querySelector('#inptPhoto'); var data = canv.toDataURL('image/png'); photo.setAttribute('src', data); } </code></pre> <p>I came across another SO post that suggested my image might not in fact be transparent, but white in the background, which is consistent with my results. Is there another way to do this?</p>
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    1. USsmulholland2
    1. USsmulholland2
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    1. COCheck script.js, line 147. Is it possible you're missing a pair of parenthesis on `drawLayers`?
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      1. POChromakey'd HTML webcam wont save with transparancy
      1. USbrianchirls
    2. COI was really hoping that was it. No luck. I changed the chroma key tolerance to be anything dark greyish.
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      1. POChromakey'd HTML webcam wont save with transparancy
      1. USsmulholland2
    3. COThe keying seems to be working okay. The background definitely is transparent. But I'm not seeing any of the images show up. Looks like they're not getting drawn to the canvas. For every frame, you have to draw first the background image and then the processed video.
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      1. POChromakey'd HTML webcam wont save with transparancy
      1. USbrianchirls
 

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