Outputting raw image stream rather than jpeg, on-the-fly image resizing - php

Question

I have a PHP function that does on-the-fly image resizing for thumbnail creation.
I am having trouble as it's just displaying raw image stream instead of the actual image.
My code is using a function called thumbnail:
$thumbnail = thumbnail($item['filename'], 209, 137);
imagejpeg($thumbnail);
I've tried putting in:
header("Content-type: image/jpeg");
However, this just expects the full page to be an image. I have absolutely no idea where to go from here, been working at it for a while. I'd rather not save the image to disk although it's looking like this might be necessary.

Answer 1

You either
Do it the normal way
This mean you point at one url, and serve the contents of one image:
<img src="myimage.php">
and myimage.php is a script that looks like:
header('Content-type: image/jpeg');
imagejpeg($thumbnail);
die;
This technique has the advantage of being.. the normal way of doing things.
OR
Output the image inline
Using data uris outputting the contents as a base64 encoded string
<img src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUA
AAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO
9TXL0Y4OHwAAAABJRU5ErkJggg==" alt="Red dot">
This technique is most appropriate with small images.
It has the advantage of meaning all the images are in the main http request - at the (possibly sizable) disadvantage of making the page harder to edit/build and possibly negating the benefits of browser caching (unless the html page is itself cached).
Being normal is easier
Regarding this statement in the question:
However, this just expects the full page to be an image
That's right - if you do it the normal way you want to point at your php script with the src attribute of an image tag, and server only an image - i.e. the exact same response as if you were pointing at an image file with a browser.
Unless you have a good reason to do things a different way - the "normal" way is a good place to start.

Answer 2

You can point an html img tag to an php file.
<img src='thumbnail.php?file=<?php echo $item['filename']; ?>' />
Then on your php file you display the image and change the headers since all it is doing is displaying an image.
$thumbnail = thumbnail($_GET['filename'], 209, 137);
imagejpeg($thumbnail);
header("Content-type: image/jpeg");

Answer 3

You need to insert the image like you would a normal image in HTML and create the image in a separate PHP file:
image.php
<?php
$img = imagecreate(100,100); //Create an image 100px x 100px
imagecolorallocate($img, 255,0,0); //Fill the image red
header('Content-type: image/jpeg'); //Set the content type to image/jpg
imagejpeg($img); //Output the iamge
imagedestroy($img); //Destroy the image
?>
myWebpage.html
<img src="image.php" />