Multiple examples of php image verification code

 //File header...
 header("Content-type: image/png");
 //Create true color white paper
 $im = @imagecreatetruecolor (50, 20) or die("Failed to create image");
 //Get the background color
 $background_color = imagecolorallocate($im, 255, 255, 255);
 //Fill the background color (this thing is similar to an oil barrel)
 imagefill($im,0,0,$background_color);
 //Get the border color
 $border_color = imagecolorallocate($im,200,200,200);
 //Draw a rectangle, border color 200,200,200
 imagerectangle($im,0,0 ,49,19,$border_color);
 //Show off the background line by line, use 1 or 0 for full screen
 for($i=2;$i / /Get a random light color
 $line_color = imagecolorallocate($im,rand(200,255),rand(200,255),rand(200,255));
 //Draw a line
 imageline($im,2,$i,47,$i, $line_color);
 }
 //Set the font size
 $font_size=12;
 //Set the printed text
 $Str[0] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
 $Str[1] = "abcdefghijklmnopqrstuvwxyz";
 $Str[2] = "01234567891234567890123456";
 //Get the first random text
 $imstr[0 ]["s"] = $Str[rand(0,2)][rand(0,25)];
 $imstr[0]["x"] = rand(2,5);
 $imstr[0 ]["y"] = rand(1,4);
 //Get the second random text
 $imstr[1]["s"] = $Str[rand(0 ,2)][rand(0,25)];
 $imstr[1]["x"] = $imstr[0]["x"]+$font_size-1+rand(0,1);
 $ imstr[1]["y"] = rand(1,3);
 //Get the 3rd random text
 $imstr[2]["s"] = $Str[ rand(0,2)][rand(0,25)];
 $imstr[2]["x"] = $imstr[1]["x"]+$font_size-1+rand(0,1) ;
 $imstr[2]["y"] = rand(1,4);
 //Get the 4th random text
 $imstr[3]["s"] = $Str[rand(0,2)][rand(0,25)];
 $imstr[3]["x"] = $imstr[2]["x"]+$font_size-1+rand(0 ,1);
 $imstr[3]["y"] = rand(1,3);
 //Write random string
 for($i=0;$i< ;4;$i++){
 //Get a random darker color
 $text_color = imagecolorallocate($im,rand(50,180),rand(50,180),rand(50,180));
 //Draw text
 imagechar($im ,$font_size,$imstr[$i]["x"],$imstr[$i]["y"],$imstr[$i]["s"],$text_color);
 }> ;
 //Display image
 imagepng($im);
 //Destroy image
 imagedestroy($im);
?>

Example 2, beautiful PHP image verification code example Complete code:

/*
 * @Author fy
 */
$imgwidth =100; //Picture width
$imgheight =40; //Picture height
$codelen =4; //Verification code length
$fontsize =20; //Font size
$charset = 'abcdefghkmnprstuvwxyzABCDEFGHKMNPRSTUVWXYZ23456789';
$font = 'Fonts/segoesc.ttf';
$im=imagecreatetruecolor($imgwidth,$imgheight);
$while=imageColorAllocate($im,255,25 5,255 );
imagefill($im,0,0,$while); //Fill the image
//Get the string
$authstr='';
$_len = strlen($charset)-1;
for ($i =0;$i $authstr .= $charset[mt_rand(0,$_len)];
}
session_start();
$_SESSION['scode']=strtolower($authstr );//Convert all to lowercase, mainly to avoid case sensitivity
//Draw random dots, which have been changed to stars
for ($i=0;$i $randcolor =imageColorallocate($im,mt_rand(200,255),mt_rand(200,255),mt_rand(200,255));
 imagestring($im,mt_rand(1,5), mt_rand(0,$imgwidth),mt_rand(0,$imgheight) , '*',$randcolor);
 //imagesetpixel($im,mt_rand(0,$imgwidth),mt_rand(0,$imgheight),$randcolor);
}
//Draw lines randomly, number of lines = characters Quantity (anything)
for($i=0;$i{
 $randcolor=imagecolorallocate($im,mt_rand(0,255),mt_rand(0,255),mt_rand(0,255));
 imageline ($im,0,mt_rand(0,$imgheight),$imgwidth,mt_rand(0,$imgheight),$randcolor);
}
$_x=intval($imgwidth/$codelen); //Calculate character distance
 $_y=intval($imgheight*0.7); //Characters are displayed at 70% of the image
for($i=0;$i $randcolor=imagecolorallocate($im ,mt_rand(0,150),mt_rand(0,150),mt_rand(0,150));
 //imagestring($im,5,$j,5,$imgstr[$i],$color3);
 // imagettftext ( resource $ image , float $size , float $angle , int $x , int $y , int $color , string $fontfile , string $text )
 imagettftext($im,$fontsize,mt_rand(-30,30),$i* $_x+3,$_y,$randcolor,$font,$authstr[$i]);
}
//Generate image
header("content-type:image/PNG");
imagePNG($im);
imageDestroy($im);

Example 3, php5 image verification code example code

Example of php5 generating image verification code.

You need to use php GD library function: 1,imagecreatetruecolor-----Create a true color image imagecreatetruecolor(int x_size,int y_size) //x represents width, y represents height 2. imagecolorallocate assigns colors (palette) to an image imagecolorallocate(resource image,int red,int green,int blue)//red,green,blue----three primary colors 3. imagestring drawing function iamgestring(resource image,font,int x,int y,content,color); 4. Output function PHP's header is an action that defines the header. PHP5 supports 3 types: 1,Content-type: xxxx/yyyy 2,Location:xxxx:yyyy/zzzz 3,Status: nnn xxxxxx xxxx/yyyy indicates the type of content file Such as: image/gif image/jpeg image/png Example: header("Content-type:image/jpeg") There are corresponding image types in the GD library imagejpeg(),imagegif(),imagepang() 5.imageline line drawing function iamgeline(resource image,int x1,int y1,int x2,int y2,int color); image ---picture x1 ---starting coordinates y1 x2 ---end point coordinates y2 6.imagesetpixel drawing point function imagesetpixel(resource image,int x,int y,int color) 7.imagettftext writing function with font imagettftext(resource image,float size,float angle,int x,int y,int color,string fontfile,string text) 8. How to insert Chinese php verification code iconv("gb2312","utf-8","string"); //First convert the text into utf-8 format 9. Random function 1, rand([int min,int max]) //rand(1,4) generates numbers from 1 to 4 2, dechex (decimal number) //Convert to hexadecimal

Steps to generate verification code: Generate random numbers -- create pictures -- write random numbers into pictures -- save in session

Enter verification code example gdchek.php

/*
* Generate image verification code
* and open the template in the editor.
*/
session_start();
for($i=0;$i$rand.=dechex(rand(1,15)); //Generate a 4-digit random number containing hexadecimal
}
$_SESSION[check_gd]=$rand;
$img=imagecreatetruecolor (100,30); //Create a picture
$bg=imagecolorallocate($img,0,0,0); //The first time the background color is generated
$fc=imagecolorallocate($img,255,255,255); // Generated font color
//Draw lines on the picture
for($i=0;$i$te=imagecolorallocate($img,rand(0,255),rand(0,255),rand(0,255 ));
imageline($img,rand(0,15),0,100,30,$te);
}
//Draw some points on the picture
for($i=0;$i$te=imagecolorallocate($img,rand(0,255),rand(0,255),rand(0,255));
imagesetpixel($img,rand()%100,rand()%30,$te);
}
 //First, convert the text into utf-8 format
//$str=iconv("gb2312","utf-8","Hehehe");
//Add Chinese verification
//smkai.ttf is In order to use a font file as a font on other people’s computers, put the file in the root directory of the project and download it. There is also
imagettftext($img,11,10,20, 20,$fc,"simkai.ttf","Hello Hello");
//Write the string in the image
//imagestring($img,rand(1,6),rand(3,70) ,rand(3,16),$rand,$fc);
//Output image
header("Content-type:image/jpeg");
imagejpeg($img);
?>

login.php

/*
*
*
*/
session_start();
if($_POST[sub]){
//Judge whether the verification code is the same
if($_POST[gd_pic ]==$_SESSION[check_gd]){
echo "Verification successful!";
}else{
echo "Verification code error";
}
}
?>
 Username:  
Password: < ;br> 
Verification code: