captcha.php

<?php
define ('start_x', 6);
define ('word_h', 31);

function get_ans($url) {

    $im = imagecreatefromjpeg($url);
    imagegif($im, '0.gif');
    $rgbArray = array();
    $res = $im;
    $size = getimagesize($url);

    $wid = $size['0'];
    $hid = $size['1'];
    for ($i = 0; $i < $hid; ++ $i) {
        for ($j = 0; $j < $wid; ++ $j) {
            $rgb = imagecolorat($res, $j, $i);
            $rgbArray[$i][$j] = imagecolorsforindex($res, $rgb);
        }
    }
    for ($i = 0; $i < $hid; $i ++) {
        for ($j = 0; $j < $wid; $j ++) {

            if ($rgbArray[$i][$j]['blue'] < 212) {
                echo '0';
            } else {
                echo '1';
            }
        }
        echo "\n";
    }

    $data = array("", "", "", "");
    $l = $wid;
    $r = 0;
    $cnt = 0;
    $pre_is_word = 0;
    for ($i = 0; $i < $wid; $i++) {
        if ($cnt > 3) break;
        $has_num = 0;
        for ($j = start_x; $j < start_x + word_h; $j++) {
            if ($rgbArray[$j][$i]['blue'] < 212) {
                $l = min($l, $i);
                $r = max($r, $i);
                $has_num = 1;
                $pre_is_word = 1;
                break;
            }
        }
        if ($has_num == 0 && $pre_is_word == 1) {
            for ($x = start_x; $x < start_x + word_h; $x++) {
                for ($y = $l; $y < $r + 1; $y++)
                    if ($rgbArray[$x][$y]['blue'] < 212) {
                        $data[$cnt] .= '0';
                        #            echo '0';
                    }
                    else {
                        $data[$cnt] .= '1';
                        #            echo '1';
                    }
                #echo "\n";
            }
            $cnt = $cnt + 1;
            $l = $wid;
            $r = 0;
            $pre_is_word = 0;
        }
    }

    #for ($i = 0; $i < 4; $i++)  echo $data[$i]."\n";
    $Keys = array(  
        '0' => '1000000000000001000000000000000000000000000000000000000000000000000001111110000000000111111000000000011111100000000001111110000000000111111000000000011111100000000001111110000000000111111000000000011111100000000001111110000000000111111000000000011111100000000001111110000000000111111000000000011111100000000001111110000000000111111000000000011111100000000001111110000000000111111000000000011111100000000001111110000000000111111000000000000000000000000000000000000000000000000000001000000000000001',
        '1' => '1100000110000011000001000000100000010000000000000000000000000001100000110000011000001100000110000011000001100000110000011000001100000110000011000001100000110000011000001100000110000011000001100000110000011000001100000',
        '2' => '1000000000000001000000000000000000000000000000000000000000000000000001111110000000000111111000000000011111100000000001111110000000000111111000000000011111100000111111111100000011111111110000001111111110000001111111111000001111111111000000111111111000000111111111100000111111111100000011111111110000011111111110000001111111110000001111111111000001111111111000000111111111100000111111111100000111111111100000011111111110000011111111110000000000000000000000000000000000000000000000000000000000000000',
        '3' => '1000000000000001000000000000000000000000000000000000000000000000000001111110000000000111111000000000011111100000000001111110000000000111111000000000011111100000111111111110000011111111100000001111111100000001111111000000011111111100000011111111110000000111111111110000000111111111100000001111111111000000111111111110000011111111111000000000011111100000000001111110000000000111111000000000011111100000000001111110000000000111111000000000000000000000000000000000000000000000000000001000000000000001',
        '4' => '11111110000001111111111100000111111111111000001111111111100000011111111111000001111111111110000011111111111000000111111111110000011111111111000000111111111110000001111111111100000111111111110000001111111111100000010000011111000001100000111100000011000001111000000110000011110000011100000111000000111000001110000001110000011100000111100000110000001111000001100000000000000000000000000000000000000000000000000000000000000000000111111111100000111111111111000001111111111110000011111111111100000111111111111000001111111111110000011',
        '5' => '0000000000000000000000000000000000000000000000000000000000000000000001111111111100000111111111110000011111111111000001111111111100000111111111110000011111111111000001111111111100000000000000010000000000000000000000000000000000000000000000001111111111100000111111111110000011111111111000001111111111100000111111111110000011111111111000000000011111100000000001111110000000000111111000000000011111100000000001111110000000000111111000000000000000000000000000000000000000000000000000001000000000000001',
        '6' => '1000000000000001000000000000000000000000000000000000000000000000000001111110000000000111111000000000011111100000000001111110000000000111111000000000011111111111000001111111111100000111111111110000011111111111000000000000000100000000000000000000000000000000000000000000000000000111111000000000011111100000000001111110000000000111111000000000011111100000000001111110000000000111111000000000011111100000000001111110000000000111111000000000000000000000000000000000000000000000000000001000000000000001',
        '7' => '0000000000000000000000000000000000000000000000000000000000000000000001111110000000000111110000000000011111000001000001111100000111111111110000011111111110000001111111111000001111111111100000111111111110000011111111110000001111111111000001111111111100000111111111110000011111111110000001111111111000001111111111100000111111111110000011111111110000001111111111000001111111111100000111111111100000011111111110000001111111111000001111111111100000111111111100000011111111110000001111111111000001111111',
        '8' => '1000000000000001000000000000000000000000000000000000000000000000000001111110000000000111111000000000011111100000000001111110000000000111111000000000011111100000000001111110000000000011110000001000000000000001110000000000001111100000000001111100000000000011100000000000000100000001110000000000011111100000000001111110000000000111111000000000011111100000000001111110000000000111111000000000011111100000000001111110000000000111111000000000000000000000000000000000000000000000000000001000000000000001',
        '9' => '1000000000000001000000000000000000000000000000000000000000000000000001111110000000000111111000000000011111100000000001111110000000000111111000000000011111100000000001111110000000000111111000000000011111100000000001111110000000000000000000000000000000000000000000000000000010000000000000001111111111100000111111111110000011111111111000001111111111100000000001111110000000000111111000000000011111100000000001111110000000000111111000000000000000000000000000000000000000000000000000001000000000000001',
        '+' => '11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111000001111111111110000011111111111100000111111111111000001111111111110000011111111111100000111111000000000000000000000000000000000000000000000000000000000000000000001111110000011111111111100000111111111111000001111111111110000011111111111100000111111111111000001111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111',
        '-' => '111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111000000000000000000000000000000000000111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111',
    ); 

    $oper = -1;
    $a = 0;
    $b = 0;

    foreach($data as $numKey => $numString)  
    {  
        $max=0.0;  
        $num = 0;  
        foreach($Keys as $key => $value)  
        {  
            $percent=0.0;  
            similar_text($value, $numString,$percent);  
            if(intval($percent) > $max)  
            {  
                $max = $percent;  
                $num = $key;  
                if(intval($percent) > 95)  {
                    if ('0' <= $key && $key <= '9') {
                        if ($oper == -1) {
                            $a = $a * 10 + intval($key - '0');
                        } else {
                            $b = $b * 10 + intval($key - '0');
                        }
                    } else if ($key == '-') {
                        $oper = 0;
                    } else {
                        $oper = 1;
                    }
                    break;  
                }
            }  
        }  
    }  
    if ($oper == 0)
        return $a - $b;
    else
        return $a + $b;
}