php - Can't change font size for GD imagestring()

Question

I'm trying to follow this example to generate an image with dynamic text.

I wanted to change the size of the font, I put even 100 instead of 4, but it still appears same as before.

I'm not very good at PHP. Any sort of help would be appreciated.

Here's an example how small it appears :(

Here's my example code -

       $font = 'arial.ttf'; //FONT SIZE

       $width = imagefontwidth($font) * strlen($string) ;
       $height = imagefontheight($font) ;
       $im = imagecreatefrompng($imageO);

       $x = imagesx($im) / 2;   //PLACEMENT CENTERISH – X
       $y = imagesy($im) / 2;   //PLACEMENT CENTERISH – Y

      // $backgroundColor = imagecolorallocate ($im, 255, 255, 255);

       $transparency = 25;
       imagesavealpha($im, true);
       $background = imagecolorallocatealpha($im, background_r, background_g, background_b, $transparency);

       $textColor = imagecolorallocate ($im, 0,0,0);
       imagestring ($im, $font, $x, $y, $string, $textColor);
       imagepng($im,$imageN[$k]);
       $w = imagesx($im);
       $h = imagesy($im);

Thanks

ADDED LATER

Ok now here it is what I have done but as a result, no text is visible in the callout box.

       $font = 'arial.ttf'; //YOUR FONT SIZE

       $im = imagecreatefrompng($imageO);
       $string = "My Text";
       $imageN ="NewImage.png";

       $transparency = 25;
       imagesavealpha($im, true);
       $background = imagecolorallocatealpha($im, background_r, background_g, background_b, $transparency);

       $textColor = imagecolorallocate ($im, 0,0,0);
       //imagestring ($im, 5, $x, $y, $string, $textColor);
       imagettftext($im, 36, 0, 10, 20, $textColor, $font, $string);
       imagepng($im,$imageN);

Answer 1

You can't put 100 - http://php.net/manual/en/function.imagestring.php

Only 1-5 (by default)

UPDATE

To be able fully control the font size you might want to use http://php.net/manual/en/function.imagettftext.php

Example (from the same site):

<?php
// Set the content-type
header('Content-Type: image/png');

// Create the image
$im = imagecreatetruecolor(400, 30);

// Create some colors
$white = imagecolorallocate($im, 255, 255, 255);
$grey = imagecolorallocate($im, 128, 128, 128);
$black = imagecolorallocate($im, 0, 0, 0);
imagefilledrectangle($im, 0, 0, 399, 29, $white);

// The text to draw
$text = 'Testing...';
// Replace path by your own font path
$font = 'arial.ttf';

// Add some shadow to the text
imagettftext($im, 20, 0, 11, 21, $grey, $font, $text);

// Add the text
imagettftext($im, 20, 0, 10, 20, $black, $font, $text);

// Using imagepng() results in clearer text compared with imagejpeg()
imagepng($im);
imagedestroy($im);
?>