Giữ bản quyền ảnh bằng watermark

<?php
 $direction = 'H';
$dim = true;
$text = '4u.jcisio.com';
$font = 2;
 
error_reporting(0);
$filename = $_SERVER['QUERY_STRING'];
 
$size = GetImageSize ($filename);
switch ($size[2])
{
 case 2:
 Header('Content-type: image/jpeg');
 $funcCreate = 'ImageCreateFromJpeg';
 $funcOutput = 'ImageJpeg';
 break;
 case 3:
 Header('Content-type: image/png');
 $funcCreate = 'ImageCreateFromPng';
 $funcOutput = 'ImagePng';
 break;
 default:
 Header ('Content-type: image/gif');
 if (! @readfile($filename))
 
 {
 $error = ImageCreate(100,40);
 $c_grey = ImageColorAllocate($error, 128, 128, 128);
 $c_white = ImageColorAllocate($error, 255, 255, 255);
 ImageFill($error, 0, 0, $c_grey);
 Imagestring($error, 5, 1, 12, 'Image error', $c_white);
 echo ImagePng($error);
 ImageDestroy($error);
 return;
 }
}
 
$width = ImageFontWidth($font)*strlen($text);
$height = ImageFontHeight($font);
 
$image = $funcCreate($filename);
if ($direction=='H')
{
 get_color($size[0]-$width-5, $size[1]-$height-5, $size[0]-5, $size[1]-5);
 ImageString($image, $font, $size[0]-$width-4, $size[1]-$height-4, $text, $color_bg);
 ImageString($image, $font, $size[0]-$width-5, $size[1]-$height-5, $text, $color);
}
else
{
 get_color($size[0]-$height-5, $size[1]-$width-5, $size[0]-5, $size[1]-5);
 ImageStringUp($image, $font, $size[0]-$height-4, $size[1]-6, $text, $color_bg);
 ImageStringUp($image, $font, $size[0]-$height-5, $size[1]-5, $text, $color);
}
echo $funcOutput($image);
ImageDestroy($image);
 
function get_color($x1, $y1, $x2, $y2)
{
 global $image, $dim, $color, $color_bg;
 if (!$dim)
 {
 $color = ImageColorAllocate($image, 0, 255, 255);
 $color_bg = ImageColorAllocate($image, 255, 0, 255);
 return;
 }
 
 for($x = $x1; $x <= $x2; $x++)
 {
 for ($y = $y1; $y <= $y2; $y++)
 {
 $colors = ImageColorsForIndex($image, ImageColorAt($image, $x, $y));
 $text_color['r'] += $colors['red'];
 $text_color['r'] /= 2;
 $text_color['g'] += $colors['green'];
 $text_color['g'] /= 2;
 $text_color['b'] += $colors['blue'];
 $text_color['b'] /= 2;
 }
 }
 $text_color['r'] = $text_color['r'] <128 ? $text_color['r'] + 128 : $text_color['r'] - 128;
 $text_color['g'] = $text_color['g'] <128 ? $text_color['g'] + 128 : $text_color['g'] - 128;
 $text_color['r'] = $text_color['r'] <128 ? $text_color['r'] + 128 : $text_color['r'] - 128;
 
 $color = ImageColorAllocate($image, $text_color['r'], $text_color['g'], $text_color['b']);
 $color_bg = ImageColorAllocate($image,
 ($text_color['r']> 128 ? 10 : 240),
 ($text_color['g']> 128 ? 10 : 240),
 ($text_color['b']> 128 ? 10 : 240));
}
?>