Working with Images in PHP: GD and Imagick

Working with Images in PHP: GD and Imagick Libraries

Image processing is one of the key tasks in web development. In PHP, two main libraries are used for this: GD (built-in) and Imagick (a wrapper over ImageMagick). In this article, we will explore their capabilities, learn how to resize, crop, add watermarks, and optimize images.

1. GD Library

GD is a standard PHP extension available on most hosting platforms. It allows you to create, modify, and save images in JPEG, PNG, GIF, and WebP formats.

Enabling and checking:

<?php// Check if the GD extension is installedif (extension_loaded('gd') && function_exists('gd_info')) {    echo "GD is installed: ";    print_r(gd_info());} else {    echo "GD not found";}?>

1.1 Resizing an Image

The most common scenario is reducing an image to the desired dimensions while maintaining proportions.

<?phpfunction resizeImage($sourcePath, $destPath, $newWidth, $newHeight) {    // Get dimensions of the source image    list($width, $height, $type) = getimagesize($sourcePath);        // Create a resource from the source file    switch ($type) {        case IMAGETYPE_JPEG:            $source = imagecreatefromjpeg($sourcePath);            break;        case IMAGETYPE_PNG:            $source = imagecreatefrompng($sourcePath);            break;        case IMAGETYPE_GIF:            $source = imagecreatefromgif($sourcePath);            break;        default:            return false;    }        // Create a new image    $newImage = imagecreatetruecolor($newWidth, $newHeight);        // Preserve transparency for PNG/GIF    imagealphablending($newImage, false);    imagesavealpha($newImage, true);        // Copy and resample    imagecopyresampled($newImage, $source, 0, 0, 0, 0, $newWidth, $newHeight, $width, $height);        // Save the result    imagejpeg($newImage, $destPath, 85); // Quality 85%        // Free memory    imagedestroy($source);    imagedestroy($newImage);    return true;}

// Usage exampleresizeImage('photo.jpg', 'photo_thumb.jpg', 300, 200);?>

1.2 Cropping an Image

Cropping allows you to extract the central part of an image at the desired size.

<?phpfunction cropCenter($sourcePath, $destPath, $cropWidth, $cropHeight) {    list($width, $height) = getimagesize($sourcePath);    $source = imagecreatefromjpeg($sourcePath);        // Calculate center coordinates    $x = ($width - $cropWidth) / 2;    $y = ($height - $cropHeight) / 2;        $newImage = imagecreatetruecolor($cropWidth, $cropHeight);    imagecopyresampled($newImage, $source, 0, 0, $x, $y, $cropWidth, $cropHeight, $cropWidth, $cropHeight);        imagejpeg($newImage, $destPath, 90);    imagedestroy($source);    imagedestroy($newImage);}

cropCenter('photo.jpg', 'photo_cropped.jpg', 400, 400);?>

1.3 Adding a Watermark

Adding text or a logo over an image.

<?phpfunction addWatermarkText($sourcePath, $destPath, $text = "© PythonLib.ru") {    $source = imagecreatefromjpeg($sourcePath);    $width = imagesx($source);    $height = imagesy($source);        // Text color (white with transparency)    $color = imagecolorallocatealpha($source, 255, 255, 255, 50);        // Font size (using built-in font)    $fontSize = 5;    $x = 10;    $y = $height - 20;        imagestring($source, $fontSize, $x, $y, $text, $color);        imagejpeg($source, $destPath, 90);    imagedestroy($source);}

addWatermarkText('photo.jpg', 'photo_watermarked.jpg');?>