CODEWITHSUNDEEP
javascriptbase64image-manipulation
Pandafinity
Pandafinity

Reputation: 713

How to resize or change resolution of base64 image through manipulating the base64 code?

There are lots of examples of encoding images to Base64. Is there a way of changing the size or resolution of that image by simply manipulating the actual base64 encoded content?

Your base64 code might be:

iVBORw0KGgoAAAANSUhEUgAAAWQAAAFjCAIAAACFfObPAAAAA3NCSVQICAjb4U/gAAAgAE...

Is there an algorithm or equation that allows you to manipulate that Base64 string to change the size of the image or change the resolution?

My question is aimed at people looking at progressive images, data manipulation, and WebP formats, which is a lossless and lossy compression of images.

I am not interested in creating Canvas elements and manipulating the contents of the canvas. I am interested in an approach that can be used either on the client or server and can be sent via HTTP or socket communication.

Upvotes: 18

Views: 37797

Answers (2)

Rodrigo García
Rodrigo García

Reputation: 13

Well this is very old but you can manipulate it using it as background with an url and background-size:contain; That way the image should show inside the height and with you establish and not be clipped by the container.

Upvotes: 0

hampusohlsson
hampusohlsson

Reputation: 10219

It is possible by using the <canvas> element

var canvas = document.createElement("canvas");
var ctx = canvas.getContext("2d");

canvas.width = 32; // target width
canvas.height = 32; // target height

var image = new Image();
document.getElementById("original").appendChild(image);

image.onload = function(e) {
    ctx.drawImage(image, 
        0, 0, image.width, image.height, 
        0, 0, canvas.width, canvas.height
    );
    // create a new base64 encoding
    var resampledImage = new Image();
    resampledImage.src = canvas.toDataURL();
    document.getElementById("resampled").appendChild(resampledImage);
};

image.src = "data:image/png; base64,iVBORw0KGgoAAAANSUhEUgAAADAAAAAwCAMAAABg3Am1AAABaFBMVEVMoUNNoURNokROokVPokZQo0dRpEhSpElTpUpUpUtVpk1Wpk1Xp09ZqFBZqFFaqFJbqVJbqVNdqlVeqlVeq1Zgq1hgrFhirFpirVtlrl5mr15nr2BpsGFqsWNssmRus2dvs2hwtGlxtGlytWtztWx4uHF5uXJ6uXR+u3d/vHiAvHqBvXqCvXyDvn2Evn6HwIGMw4aPxImRxYuUx46Vx5CWyJGbypacy5egzZuizp2kz5+kz6Cm0KGn0aKp0qSp0qWs1Kiu1Kmw1ayy1q602LC12LG627e83Lm+3bvF4cPI4sXJ48bK48jL5MjM5MrN5cvP5szQ5s7R58/S59DU6dLV6dPa7Nnf7t7g79/h79/i8OHj8OLk8ePm8uXn8ubp9Ojq9Onr9ers9evt9ezu9u3v9+7w9+/x+PDy+PHy+PL0+fP0+fT1+vX2+vX3+/f4+/j5/Pj5/Pn6/Pr7/fv9/v3+/v7+//7////VxbUKAAABVElEQVR4Ae3L65cKcQDH4e9YYe2utMnFsuu+rCyFKDVyKSTG/X6RVO5Ums+/r3HQOZz5zcyb7U3P+0drbcLKVRVF/DacVQSbnkL/oCJY+Axv4orgpAvOlMJYvJXU0GWgqBBSDd4ekhR7CINjClYGellJ21rwfocCWYUBcDUmHfkBj2IKlv4EPEhI54GKQlh4DjQOyKoBp2Syf1qemZtAN6PZV/Btr/xNdz5cnNeQVXKBK+uXvsNd+TsH9K4taujEF+D+1iw35uTP7gK4zlFL2vMCeL1vWUaJC208jzMbNFsHzijIxtPP8LzLz62z3UsKwTp+D8/Xyq7DUzKZ36nflq73AXpbZFSi49irKXm2lz9CVWZ3+KVVL6aT0ubcy90ye8JIs1ZYiStIYqVQa/JXXr4A/ZFMF+stPMsSYAojqVXbac+EDiPmwD/GH/431mAwhmA28RMGFbXqgVfHnwAAAABJRU5ErkJggg==";
<p>Original (48x48)</p>
<div id="original"></div>
<p>Resampled (32x32)</p>
<div id="resampled"></div>

Upvotes: 17

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