Cropping image in PHP

I'd like crop an image in PHP and save the file. I know your supposed to use the GD library but i'm not sure how. Any ideas?

Thanks

You could use imagecopy to crop a required part of an image. The command goes like this:

imagecopy  ( 
    resource $dst_im - the image object ,
    resource $src_im - destination image ,
    int $dst_x - x coordinate in the destination image (use 0) , 
    int $dst_y - y coordinate in the destination image (use 0) , 
    int $src_x - x coordinate in the source image you want to crop , 
    int $src_y - y coordinate in the source image you want to crop , 
    int $src_w - crop width ,
    int $src_h - crop height 
)

Code from PHP.net - a 80x40 px image is cropped from a source image

<?php
// Create image instances
$src = imagecreatefromgif('php.gif');
$dest = imagecreatetruecolor(80, 40);

// Copy
imagecopy($dest, $src, 0, 0, 20, 13, 80, 40);

// Output and free from memory
header('Content-Type: image/gif');
imagegif($dest);

imagedestroy($dest);
imagedestroy($src);
?>

This function will crop image maintaining image aspect ratio :)

 function resize_image_crop($image, $width, $height)
     {

        $w = @imagesx($image); //current width

        $h = @imagesy($image); //current height
        if ((!$w) || (!$h)) { $GLOBALS['errors'][] = 'Image couldn\'t be resized because it wasn\'t a valid image.'; return false; }
        if (($w == $width) && ($h == $height)) { return $image; }  //no resizing needed
        $ratio = $width / $w;       //try max width first...
        $new_w = $width;
        $new_h = $h * $ratio;    
        if ($new_h < $height) {  //if that created an image smaller than what we wanted, try the other way
            $ratio = $height / $h;
            $new_h = $height;
            $new_w = $w * $ratio;
        }
        $image2 = imagecreatetruecolor ($new_w, $new_h);
        imagecopyresampled($image2,$image, 0, 0, 0, 0, $new_w, $new_h, $w, $h);    
        if (($new_h != $height) || ($new_w != $width)) {    //check to see if cropping needs to happen
            $image3 = imagecreatetruecolor ($width, $height);
            if ($new_h > $height) { //crop vertically
                $extra = $new_h - $height;
                $x = 0; //source x
                $y = round($extra / 2); //source y
                imagecopyresampled($image3,$image2, 0, 0, $x, $y, $width, $height, $width, $height);
            } else {
                $extra = $new_w - $width;
                $x = round($extra / 2); //source x
                $y = 0; //source y
                imagecopyresampled($image3,$image2, 0, 0, $x, $y, $width, $height, $width, $height);
            }
            imagedestroy($image2);
            return $image3;
        } else {
            return $image2;
        }
    }