Using PHP getimagesize() to Retrieve Image Dimensions

The getimagesize() function in PHP can determine the size, dimensions, and file type of a wide range of image formats such as GIF, JPG, PNG, BMP, and more, returning an array that includes the width, height, and MIME type.

Its return value is an indexed array where index 0 holds the image width and index 1 holds the image height; additional information such as the MIME type is available in the associative element 'mime'.

Example usage:

<?php
$size = getimagesize($filename);
$fp = fopen($filename, "rb");
if ($size && $fp) {
    header("Content-type: {$size['mime']}");
    fpassthru($fp);
    exit;
} else {
    // error handling
}
?>