How can you generate thumbnail with php?

You can read about two popular thumbnail generating methods in this article. The first method requires GD library. If you select the other way you need Imagick which is a native php extension to create and modify images using the ImageMagick API. Let's see the code!

First method: GD library

function gd_thumbnail($filename, $width = 200, $height = 200) {
    $source = imageCreateFromString(file_get_contents($filename));
    $x = imageSX($source);
    $y = imageSY($source);

    if ($x > $y) { // landscape orientation
        $height = intval($y/($x/$width));
    } else { // square or portrait orientation
        $width = intval($x/($y/$height));
    }

    $destination = ImageCreateTrueColor($width, $height);
    imageCopyResamled($destination, $source, 0, 0, 0, 0, $width, $height, $x, $y);
    imagejpeg($destination, NULL, 92);
}

Second method: Imagick extension

function im_thumbnail($filename, $width = 200, $height = 200) {
    $image = new Imagick($filename);
    $image->thumbnailImage($width, $height, TRUE);
    echo $image;
}

Usage

You can generate thumbnail image to visitor's browser:

header('Content-type: image/jpeg');
im_thumbnail('path/to/image.jpg'); // you can use gd_thumbnail() here

This code will response a JPEG image.

You can save thumbnail image to file:

$fileContent = gd_thumbnail('path/to/image.jpg'); // you can use im_thumbnail() here
file_put_contents('path/to/image_thumbnail.jpg', $fileContent); // save image

This is very easy, isn't it?

Have a nice day, and use these code as you need.