The code uses PHP to resize an image (currently only jpeg). Using this method, the resized image is of much better quality than a browser-side resizing. The file size of the new downsized image is also smaller (quicker to download).
The code comes in two parts:
- imageResizer() is used to process the image
- loadimage() inserts the image url in a simpler format
<?php function imageResizer($url, $width, $height) { header('Content-type: image/jpeg'); list($width_orig, $height_orig) = getimagesize($url); $ratio_orig = $width_orig/$height_orig; if ($width/$height > $ratio_orig) { $width = $height*$ratio_orig; } else { $height = $width/$ratio_orig; } // This resamples the image $image_p = imagecreatetruecolor($width, $height); $image = imagecreatefromjpeg($url); imagecopyresampled($image_p, $image, 0, 0, 0, 0, $width, $height, $width_orig, $height_orig); // Output the image imagejpeg($image_p, null, 100); } //works with both POST and GET $method = $_SERVER['REQUEST_METHOD']; if ($method == 'GET') { imageResize($_GET['url'], $_GET['w'], $_GET['h']); } elseif ($method == 'POST') { imageResize($_POST['url'], $_POST['w'], $_POST['h']); } // makes the process simpler function loadImage($url, $width, $height){ echo 'image.php?url=', urlencode($url) , '&w=',$width, '&h=',$height; } ?>Usage
Above code would be in a file called image.php.
Images would be displayed like this:
<img src="<?php loadImage('image.jpg', 50, 50) ?>"
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Whats about GIF and PNG?
Get/Post
$method = $_SERVER[‘REQUEST_METHOD’];
…
Should go with
imageResize($_REQUEST[‘url’], $_REQUEST[‘w’], $_REQUEST[‘h’]);
Hi! How would you format the link so that it includes the required alternate tag for the image?
I am trying to link to images in specific directories but it encodes URL so images come back black.
Is there a way to modify script to prevent encoding URL?
Tom,
I think (not sure) your problem is not ENCODEDING stuff.
I think problems is URL invocation:
Depends of PHP installation your URLs has to be /root/ directory based not domain (http://www…..) related, means:
if you try to use a image in a directory “inside” same php installation (means image is in the same server as the resize script) you have to use something like this:
/root/www/domain/htpdocs/images/yourimage.jpg instead:
http://www.doamin.com/images/yourimage.jpg
to find out your “real” path use: PHP supervariable
$_SERVER[“DOCUMENT_ROOT”]
$myPath = $_SERVER[“DOCUMENT_ROOT”];
$myImage = $mypath . “/images/myimagen.jpg”;
or better check this trick (that works perfect for us in all or scripts):
if (!file_exists($urlImage)) $urlImage=str_ireplace(‘http://’.$_SERVER[“HTTP_HOST”],$_SERVER[“DOCUMENT_ROOT”],$urlImage);
Got it? it reemplace “http://www.domain.com” with your “real” path IF “don’t” find the image (means internal image)
Hope this help you.
Be aware of the high CPU RESOURCES used by functions like imagecreatetruecolor(), imagecreatefromjpeg(), imagecopyresampled() and other PHP image’s related functions.
We used a PHP resize approcach in a high traffic website and we have to remove it because CPU SERVER RESOURCES were going crazy a couple of times a crash occurs (a resize process for every single user) we opted for a different approach (a WordPress like) at the moment of upload we create different sizes to be served (WordPress do that when a image is used in their posts)
This would work perfectly with a client-side service like picturePolyfill. Give it a try!
How do you add support for png?
This resize code is very good for version 1.0.
For version 2.0, it would be great to save the aspect-ratio, by given width OR height (strictly only one of them).
For version 3.0: cached images (with restricted sizes) ;)
(I will do these for myself)
I have given below code for all type of basic image format.
function imageResizer($url, $width, $height) {