Tim Brockman . com

ASCII Art converter resampled

• Tim Brockman
• @ 4:37 am

In an earlier post I wrote a some quick code to convert simple gif images to ASCII Art using PHP GD functions. In case you didn't notice, things get distorted because pixels are square however ASCII symbols are rectangular and have spacing between each line. In my measurements this is about 8x11 (Width x Height) which means we need to squish the image to about 70% of its original height before turning it into ASCII art. (after further testing 66% looked better to me)

In order to do this we can use one of 2 functions, ImageCopyResized() or ImageCopyResampled(). For this the latter, tends to be cleaner but slower, so I'll use that. I'll also need ImageCreateTrueColor() to create the image to become the resampled copy's destination.

So here's the new code created from the old code.

giftoascii_resampled.php

<?
// displays gif as ascii art

$raw_image = imagecreatefromgif("images/dobbshead.gif");
$xlimit = imagesx($raw_image);
$raw_height = imagesy($raw_image);
$ylimit = floor($raw_height * 0.7); // or 0.66
$the_image = imagecreatetruecolor($xlimit, $ylimit);
imagecopyresampled($the_image, $raw_image, 0, 0, 0, 0, $xlimit, $ylimit, $xlimit, $raw_height);

print("<tt>\n");
for($ycurrent=0; $ycurrent < $ylimit; $ycurrent++){
for($xcurrent=0; $xcurrent < $xlimit; $xcurrent++){
$current_color = imagecolorat($the_image, $xcurrent, $ycurrent);
$rgb = imagecolorsforindex($the_image, $current_color);
$color_score = $rgb['red'] + $rgb['green'] + $rgb['blue'];
if($color_score < 300){
//black color
print("M");
}elseif($color_score > 600){
//white color
print("&nbsp;");
}else{
//gray color
print("$");
}
// print($color_score);

}
print("<br />\n");
}
print("</tt>\n");
imagedestroy($the_image);
imagedestroy($raw_image);
?>

Don't forget to add the second imagedestroy.

This can be seen in action here --> Resampled gif to ASCII art with PHP GD

and compared to the original version here --> gif to ASCII

Now that the code is modified to display images in proportion it is more appropriate for designs where proper geometry is more important like type or logos.