TalkPHP - Applying a Filter in GD

TalkPHP (http://www.talkphp.com/forums.php)

- Tips & Tricks (http://www.talkphp.com/tips-tricks/)

- - Applying a Filter in GD (http://www.talkphp.com/tips-tricks/1897-applying-filter-gd.html)

Applying a Filter in GD

In Rendair's thread about the wave effects for the reflections, somebody mentioned that you can apply overlay filters which affect the image below. So for example if I had a captcha image below, how could I apply a wave effect on the top to skew those letters?

What I'm trying to do is replicate the Gmail captcha image which is very simple, but merely skews the letters:

Could you give me an example of the Google Mail Captcha system?

Can you not see the image in my original post? :-(

I believe they use Imagick, not GD. The reason for this is the object has a direct "distortImage" method, and I cannot find a similar filter for GD. This is by best guess.

PHP: Imagick::distortImage - Manual

Quote:

Originally Posted by Wildhoney (Post 7912)

Can you not see the image in my original post? :-(

Sorry a bit tired.

Thanks for your replies. So in that case, what is Kalle going on about in this post?

I honestly have no clue, I'm not very experienced with GD. I do browse the manuals as I find questions though. From what I understand, as of PHP5, there's no predefined filter for waves or "wet floor"-like effects. imagefilter() is the function that applies a filter, but the defined constants don't include a wave filter.

Maybe they have a newer version?

Edit:

I think I found it, all the functions are hand made using the imagecopy() function. Some of the user contributed code is(authors bolded before the code):
administrador(ensaimada)sphoera(punt)com

PHP Code:


		
			
function wave_region($img, $x, $y, $width, $height,$grade=5){

        for ($i=0;$i<$width;$i+=2){

            imagecopy($img,$img,

                $x+$i-2,$y+sin($i/10)*$grade,     //dest

                $x+$i,$y,             //src

                2,$height);

        }

    }

designerkamal at gmail dot com

PHP Code:


		
			
function Skew($src, $dest, $skew_val)

{

  $imgsrc = imagecreatefromgif($src);

  $width = imagesx($imgsrc);

  $height = imagesy($imgsrc);

  $imgdest = imagecreatetruecolor($width, $height+($height*$skew_val));

  $trans = imagecolorallocate($imgdest,0,0,0);

  $temp=0;

  for($x=0 ; $x<$width ; $x++)

   {

     for($y=0 ; $y<$height ; $y++)

    {

        imagecopy($imgdest, $imgsrc, $x, $y+$temp, $x, $y, 1, 1);

      imagecolortransparent($imgdest,$trans);

       

    }

    $temp+=$skew_val;

   }

  imagepng($imgdest, $dest);

  imagedestroy($imgsrc);

  imagedestroy($imgdest);

}

You could probably inspire some code for yourself based off these two functions, and get a slightly wavy skew filter.