javascript - If statement changing image to greyscale -


currently have image converted greyscale, on click of button. need able remove function either using same button or button. thought possible using if statement although im not sure how this.

<html> <body> <script>      function greyscale(){     //get canvas         var canvas = document.getelementbyid("canvas");     //get context property     var ctx = canvas.getcontext('2d');     //get image     var image = document.getelementbyid("imgsrc");     //draw image canvas     ctx.drawimage(image,0,0);     //get image data     var imagedata = ctx.getimagedata(0,0,130,130);     //get pixel data     var px = imagedata.data;     //get entire length of pixel data     var length = px.length;      //loop , manipulate pixels     for(var i=0;i<length;i+=4){         var redpx = px[i];         var greenpx = px[i+1];         var bluepx = px[i+2];         var alphapx = px[i+3];              //create greyscale sub pixel         var greyscale = redpx*.3 + greenpx * .59 + bluepx * .11;          //store each subpixel greyscale subpixel         px[i] = greyscale;         px[i+1] = greyscale;         px[i+2] = greyscale;          }      //put manipulated image data canvas     ctx.putimagedata(imagedata,0,0);      } </script><img src="flower.jpg" id="imgsrc"/> <canvas id="canvas" width="130" height="130"></canvas>  <br>  </script>  <input id="btngreyscale" type="button" value="greyscale" onclick="greyscale();" /> <input id="btngreyscaleoff" type="button" value="greyscale off" onclick="loadimage();" />  <br> <input type="radio" name="zing" id="on" checked/>on <input type="radio" name="zing" id="off"/>off  <script type="text/javascript"> if (document.getelementbyid('btngreyscale').checked) { alert('on'); } else { (document.getelementbyid('btngreyscaleoff').checked)  alert('off'); } </script>  </body> </html>

as roman hocke said, not able use greyscale turn colorful image, since threw information away. go colorful image have redraw first image.

so in code be:

(document.getelementbyid('btngreyscaleoff').checked)     alert('off');    ctx.drawimage(image,0,0);  }

this can done because have saved image object in dom.


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