Save images after using CSS filter

Question

I\'m building a new website that will let users apply filters to images (just like Instagram). I will use -webkit-filter for that.

The user must be able

Answer 1

You can't save images directly, but you can render them in Canvas, then save from there.

See: Save HTML5 canvas with images as an image

Answer 2

There is no direct/straight forward method to export an image with CSS Filter.

Follow the below steps for Saving/Exporting an Image with -webkit-filter applied on it:
1. Render the image to a canvas:

var canvas = document.createElement('canvas');
canvas.id="canvasPhoto";
canvas.width = imageContaainer.width;
canvas.height = imageContaainer.height;
var ctx = canvas.getContext('2d');
ctx.drawImage(imageContaainer, 0, 0, canvas.width, canvas.height);

2. Get the ImageData from canvas and apply the filter. Eg: I will apply grayscale filter to the ImageData below:

   function grayscale(ctx) {
   var pixels = ctx.getImageData(0,0,canvas.width, canvas.height);
   var d = pixels.data;
   for (var i=0; i<d.length; i+=4) {
       var r = d[i];
       var g = d[i+1];
       var b = d[i+2];
       var v = 0.2126*r + 0.7152*g + 0.0722*b;
       d[i] = d[i+1] = d[i+2] = v
   }
   context.putImageData(pixels, 0, 0);
   }
   

3. Add an event and use the below code to trigger download

   function download(canvas) {
      var data = canvas.toDataURL("image/png");
      if (!window.open(data)) 
      {
          document.location.href = data;
      }
   }