PHP 实现的将图片转换为TXT

<?php/*2015年10月19日10:24:59*/// 打开一幅图像$file_name='d:/ascii_dora.png';$chars = "$@B%8&WM#*oahkbdpqwmZO0QLCJUYXzcvunxrjft//|()1{}[]?-_+~<>i!lI;:,/"^`'. ";function getimgchars($color_tran,$chars){  $length = strlen($chars);  $alpha=$color_tran['alpha'];  $r=$color_tran['red'];  $g=$color_tran['green'];  $b=$color_tran['blue'];  $gray = intval(0.2126 * $r + 0.7152 * $g + 0.0722 * $b);  if($gray==0){    return '.';  }  if($gray<196){     $unit = (256.0 + 1)/$length;    return $chars[intval($gray/$unit)];  }  return " ";}function color_img($color_tran,$chars){  $length = strlen($chars);  $alpha=$color_tran['alpha'];  $r=$color_tran['red'];  $g=$color_tran['green'];  $b=$color_tran['blue'];  $gray = intval(0.2126 * $r + 0.7152 * $g + 0.0722 * $b);  $rand=rand (0, $length-1);  $color="rgb(".$r.",".$g.",".$b.")";  $char=$chars[$rand];  return '<span style="color:'.$color.'" >'.$char."</span>";;  }function resize_img($file_name,$chars,$flage=true){  //header('Content-Type: image/jpeg');  list($width, $height,$type) = getimagesize($file_name);  $fun='imagecreatefrom' . image_type_to_extension($type, false);  if($type==3){    $flage=false;  }  $fun($file_name);  $new_height =100;  $percent=$height/$new_height;  $new_width=$width/$percent;  $image_p = imagecreatetruecolor($new_width, $new_height);  $image = $fun($file_name);  imagecopyresampled($image_p, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);  if($flage){    return $image_p;  }else{    return $image;  }}$im=resize_img($file_name,$chars);$width=imagesx($im);$height=imagesy($im);$back_text="";for($i=1;$i<=$height;$i++){  for($j=1;$j<=$width;$j++){    $color_index = imagecolorat($im, $j-1, $i-1);    $color_tran = imagecolorsforindex($im, $color_index);    $back_text.=color_img($color_tran,$chars,false);  }  $back_text.="<br/>";} echo "<pre>";echo $back_text;echo "</pre>";//file_put_contents('1.txt',$back_text);