1. <?php 
2. session_start(); 
3. header("content-type: image/png"); 
4. $str = "的一是在了不和有大这主中人上为们地个用工时要动国产以我到绳穷塘燥泡袋朗喂铝软渠颗惯贸粪综墙趋彼届墨碍启逆卸航雾冠丙街莱"; 
5. $imgwidth = 110; 
6. $imgheight = 24; 
7. $authimg = imagecreate($imgwidth,$imgheight); 
8. $bgcolor = imagecolorallocate($authimg,255,255,255); 
9. $fontfile = "wrzc_net.ttf"; 
10. $white=imagecolorallocate($authimg,234,185,95); 
11. imagearc($authimg, 150, 8, 20, 20, 75, 170, $white); 
12. imagearc($authimg, 100, 7,50, 22, 75, 175, $white); 
13. imageline($authimg,20,20,180,30,$white); 
14. imageline($authimg,20,18,170,50,$white); 
15. imageline($authimg,25,50,80,50,$white); 
16. $noise_num = 100; 
17. $line_num = 5; 
18. imagecolorallocate($authimg,0xff,0xff,0xff); 
19. $rectangle_color=imagecolorallocate($authimg,0xaa,0xaa,0xaa); 
20. $noise_color=imagecolorallocate($authimg,0x33,0x33,0x33); 
21. $font_color=imagecolorallocate($authimg,0x00,0x00,0x00); 
22. $line_color=imagecolorallocate($authimg,0x00,0x00,0x00); 
23. for($i=0;$i<$noise_num;$i++){ 
24.  imagesetpixel($authimg,mt_rand(0,$imgwidth),mt_rand(0,$imgheight),$noise_color); 
25. } 
26. for($i=0;$i<$line_num;$i++){ 
27.  imageline($authimg,mt_rand(0,$imgwidth),mt_rand(0,$imgheight),mt_rand(0,$imgwidth),mt_rand(0,$imgheight),$line_color); 
28. }//开源代码phpfensi.com 
29. $randnum=rand(0,strlen($str)-4); 
30. if($randnum%2)$randnum+=1; 
31. $str = substr($str,$randnum,8); 
32. $_session['supdesverify'] = $str; 
33. $str = iconv("gb2312","utf-8",$str); 
34. imagettftext($authimg, 20, 0, 0, 21, $font_color, $fontfile, $str); 
35. imagepng($authimg); 
36. imagedestroy($authimg); 
37. ?> 

原文链接：http://www.phpfensi.com/php/20140819/4437.html