GD Library is used to create and manipulate image files in common formats like JPEG, PNG, GIF. It supports functions to create and modify images, set colors, and add text. Key functions include imagecreate to generate a blank image, imagecolorallocate to set colors, and imagettftext to add text to an image from a TrueType font. Code examples demonstrate creating an image, allocating colors, adding text with a font, and drawing ellipses before outputting the image.

1. GD Library
Jigar Makhija

2. Introduction
• It is used to create and manipulate image files in a variety of different
image formats, including GIF, PNG, JPEG, WBMP, and XPM.
• Fonts in GD are identified by numbers.
For Reference: https://www.php.net/manual/en/book.image.php

3. GD supports a varity of formats, below is a list of
formats supported by GD.

4. Functions
• // Create the size of image or blank image
$image = imagecreate(500, 300);
or
$image=imagecreatetruecolor($w,$h);
• // Set the background color of image and Setting the text color of
image
• $color = imagecolorallocate($image, 255, 255, 255);

5. Functions
// Function to create image which contains string.
//bool imagestring( $image, $font, $x, $y, $string, $color )
• imagestring($image, 5, 50, 100, " A computer portal", $text_color);
or
• imagettftext($image,40,0,50,50,$blacktext,$font,$text);
• header("content-type: image/png");
• imagepng($image);
• imagedestroy($image);

6. Code to implement <?php
//Set the Content Type
header('content-type:image/png');
$w=730;
$h=450;
//imagecreatefromjpeg(string $filename): GdImage|false
$image=imagecreatefrompng("img.png");
$text='hello world';
$whitebackground=imagecolorallocate($image,255,200,255);
$blacktext=imagecolorallocate($image,0,255,0);
$font =$font_path = dirname(__FILE__) . '/font.ttf';
imagettftext($image,40,0,50,50,$blacktext,$font,$text);
imagepng($image);
imagedestroy($image);
?>
<?php
$w=730;
$h=450;
$image=imagecreatetruecolor($w,$h);
$bg = imagecolorallocate($image, 0, 0, 0);
$col_ellipse = imagecolorallocate($image, 255, 255, 255);
imageellipse($image, 200, 150, 300, 200, $col_ellipse);
Header('content-type:image/jpeg');
imagejpeg($image);
?>