Resizing images with PHP
The following script will easily allow you to resize images using PHP.
The code
/* * File: SimpleImage.php * Author: Simon Jarvis * Copyright: 2006 Simon Jarvis * Date: 08/11/06 * Link: http://www.white-hat-web-design.co.uk/articles/php-image-resizing.php * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details: * http://www.gnu.org/licenses/gpl.html * */ class SimpleImage { var $image; var $image_type; function load($filename) { $image_info = getimagesize($filename); $this->image_type = $image_info[2]; if( $this->image_type == IMAGETYPE_JPEG ) { $this->image = imagecreatefromjpeg($filename); } elseif( $this->image_type == IMAGETYPE_GIF ) { $this->image = imagecreatefromgif($filename); } elseif( $this->image_type == IMAGETYPE_PNG ) { $this->image = imagecreatefrompng($filename); } } function save($filename, $image_type=IMAGETYPE_JPEG, $compression=75, $permissions=null) { if( $image_type == IMAGETYPE_JPEG ) { imagejpeg($this->image,$filename,$compression); } elseif( $image_type == IMAGETYPE_GIF ) { imagegif($this->image,$filename); } elseif( $image_type == IMAGETYPE_PNG ) { imagepng($this->image,$filename); } if( $permissions != null) { chmod($filename,$permissions); } } function output($image_type=IMAGETYPE_JPEG) { if( $image_type == IMAGETYPE_JPEG ) { imagejpeg($this->image); } elseif( $image_type == IMAGETYPE_GIF ) { imagegif($this->image); } elseif( $image_type == IMAGETYPE_PNG ) { imagepng($this->image); } } function getWidth() { return imagesx($this->image); } function getHeight() { return imagesy($this->image); } function resizeToHeight($height) { $ratio = $height / $this->getHeight(); $width = $this->getWidth() * $ratio; $this->resize($width,$height); } function resizeToWidth($width) { $ratio = $width / $this->getWidth(); $height = $this->getheight() * $ratio; $this->resize($width,$height); } function scale($scale) { $width = $this->getWidth() * $scale/100; $height = $this->getheight() * $scale/100; $this->resize($width,$height); } function resize($width,$height) { $new_image = imagecreatetruecolor($width, $height); imagecopyresampled($new_image, $this->image, 0, 0, 0, 0, $width, $height, $this->getWidth(), $this->getHeight()); $this->image = $new_image; } }
Usage
Save the above file as SimpleImage.php and take a look at the following examples of how to use the script.
The first example below will load a file named picture.jpg resize it to 250 pixels wide and 400 pixels high and resave it as picture2.jpg
include('SimpleImage.php'); $image = new SimpleImage(); $image->load('picture.jpg'); $image->resize(250,400); $image->save('picture2.jpg');
If you want to resize to a specifed width but keep the dimensions ratio the same then the script can work out the required height for you, just use the resizeToWidth function.
include('SimpleImage.php'); $image = new SimpleImage(); $image->load('picture.jpg'); $image->resizeToWidth(250); $image->save('picture2.jpg');
You may wish to scale an image to a specified percentage like the following which will resize the image to 50% of its original width and height
include('SimpleImage.php'); $image = new SimpleImage(); $image->load('picture.jpg'); $image->scale(50); $image->save('picture2.jpg');
You can of course do more than one thing at once. The following example will create two new images with heights of 200 pixels and 500 pixels
include('SimpleImage.php'); $image = new SimpleImage(); $image->load('picture.jpg'); $image->resizeToHeight(500); $image->save('picture2.jpg'); $image->resizeToHeight(200); $image->save('picture3.jpg');
The output function lets you output the image straight to the browser without having to save the file. Its useful for on the fly thumbnail generation
header('Content-Type: image/jpeg'); include('SimpleImage.php'); $image = new SimpleImage(); $image->load('picture.jpg'); $image->resizeToWidth(150); $image->output();
The following example will resize and save an image which has been uploaded via a form
if( isset($_POST['submit']) ) { include('SimpleImage.php'); $image = new SimpleImage(); $image->load($_FILES['uploaded_image']['tmp_name']); $image->resizeToWidth(150); $image->output(); } else {
<form action="upload.php" method="post" enctype="multipart/form-data"> <input type="file" name="uploaded_image" /> <input type="submit" name="submit" value="Upload" /> </form>
}
Further Information
This script will eventually be developed further to include functions for easily sharpening, bluring, cropping, brightening and colouring images.
If you have any problems using this script please email us. If you find this script useful then please consider linking to this page or why not make a donation to the developer via paypal.




