Resizing base64 Images

I have multiple Images - saved as Base64 Strings and now i want to resize these images to get thumbnails of them...

Best would be using Javascript (Node-Server) to resize them, but it would be possible to resize them with php, too.

Thanks in advance

Your best bet is to use PHPThumb in PHP.

An alternative is to invoke ImageMagick however you prefer:

No idea how to do that (or well, anything) in node.js, but the PHP bit of your question is certainly possible. After parsing the Base64, load it into a GD image and then resample it.

http://php.net/manual/en/function.imagecopyresampled.php

I agree to the method from Jon Hanna: Do Parsing the Base64code then load it to GD Image before Resample. However to get it back as data it is not as easy as I though. On php in GAE it will need to enable output buffering by setting output_buffering = "On" in php.ini file.

Here I explain the step in detail.

This doc is taken as reference to Create Image Resource using the Parsing of Base64code: http://php.net/manual/en/function.imagecreatefromstring.php

// Create image resource from Base64code
$data64 = 'iVBORw0KGgoAAAANSUhEUgAAABwAAAASCAMAAAB/2U7WAAAABl'
        . 'BMVEUAAAD///+l2Z/dAAAASUlEQVR4XqWQUQoAIAxC2/0vXZDr'
        . 'EX4IJTRkb7lobNUStXsB0jIXIAMSsQnWlsV+wULF4Avk9fLq2r'
        . '8a5HSE35Q3eO2XP1A1wQkZSgETvDtKdQAAAABJRU5ErkJggg==';
$image = imagecreatefromstring(base64_decode($data64));

This is an image resource which can be directly put to the Resample function: http://php.net/manual/en/function.imagecopyresampled.php

// Resample
$image_p = imagecreatetruecolor($new_w, $new_h);
imagecopyresampled($image_p, $image, 0, 0, 0, 0, $new_w, $new_h, $org_w, $org_h);

The result is also an image resource. To get it as a data we need Buffering.
See how to create a base64encoded string from image resource

// Buffering
ob_start();
imagepng($image_p);
$data = ob_get_contents();
ob_end_clean();

Using doc below I set a GCS bucket on my project as a website so I can Store & Display it directly: https://cloud.google.com/storage/docs/website-configuration#tips

//Store & Display
$context = stream_context_create([
   'gs' =>[
        'acl'=> 'public-read', 
        'Content-Type' => 'image/jpeg', 
        'enable_cache' => true, 
        'enable_optimistic_cache' => true,
        'read_cache_expiry_seconds' => 300,
    ]
]);
file_put_contents("gs://mybucket/resample/image.jpeg", $data, false, $context); 
header("Location: http://mybucket/resample/image.jpeg");