First off, we get 3 variables passed when the script is called (see last section). $image is the full URL of the image we want the thumbnail to be of. $newWidth and $newHeight is the width and height you would like the thumbnail to be.

Next we find out the width and height of the full image we are using, and store it in the variables $width and $height

Next we take the current width of the image and take off the wanted width. This means when the image is cropped it will not get cropped too close to the edge.

The same is then done for the height

Now we generate x and y co-ordinates where the thumnail will start cropping from. There are a few ways this could be done to achieve different results, however I opted to simply half the width and height

The next part of the code makes a copy of the image to an image named $src.

Next a blank image is created with the wanted width and height

Now we can generate our actual thumbnail. This line of code copies the old image to the blank one, starting and the generated x and y co-ordinates. This will therefore crop the image at the specified size

Now we can display the image

Finally, destroy images from memory

And thats it, as I said at the start, this script can be used in many situations and at different sizes.

Finally, to use the script in your code use the following line of html. Rather than pointing the src of the img tag to an image, it points to this php script and pass the location of the image, width and height along with it.