Reduce image quality on the fly and display lower quality version

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I have a competition website that uses WordPress allowing users to submit images. There are 700+ entries with up to 6 images each, with a maximum filesize of 3mb for each image.

I’ve then listed all the entries as posts, then on each post it displays the images.

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Each image is displayed using the_field('image1');, the_field('image2');, the_field('image3'); etc.

The problem I have is that the page is then trying to load 6 images at 3mb’s a time. Is there a way to optimise the image on the fly and show it at 50% quality?

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4 comments

  1. You can resize the picture on the fly after extracting it from a database (or file) without having to create another temporary file. Presumably you have a URL which gets an image from the database.

    $pdo = new PDO("somewhere");
$sql = "SELECT image_data FROM pictures WHERE id=1";

$stmt = $pdo->query( $sql );
$obj = $stmt->fetch(PDO::FETCH_OBJ);

$img = imagecreatefromstring($obj->image_data);

header('Content-Type: image/jpeg');
imagejpeg($img, NULL, 50);

imagedestroy($img);

    If you pass NULL as a file name to imagejpeg it will write the jpeg to standard out. The 3rd parameter is the quality level, in this case 50%.

  3. $file =  $_GET['file'];//URL with img parameter http://localhost/fk/test.php?file=1.jpeg
$quality = 40; //Change What quality you needed
$location = "images/".$file;
$image = imagecreatefromjpeg($file);
imagejpeg($image, $location, $quality) ;
header('Content-Type: image/jpeg');
    header('Content-Length: ' . filesize($location));
    header('Content-Disposition: inline; filename="'.$file.'"');
    echo file_get_contents($location);

  4. There is no way to resize images on the fly. There is only straight way to make CPU choke with such a denial-of-service self-attack.

    Images have to be pre-resized to reasonable size and quality right after upload. Every web-site in the world does it this way.