Summary of PHP image processing functions

PHP, as a very popular programming language, also has many functions for image processing. These functions can help us process and operate images more conveniently. In this article, we will mainly introduce some commonly used PHP image processing functions.

1. imagecreatefromjpeg, imagecreatefromgif, imagecreatefrompng
   These three functions are used to create images in JPEG, GIF and PNG formats respectively.
   For example, use the imagecreatefromjpeg function to load a JPEG format image into PHP:

   $image = imagecreatefromjpeg("example.jpg");

2. imagecopyresampled
   This function is used to resample and copy an image. Typically used to change image size.
   For example, to reduce an image to half its original size:

   $width = imagesx($image);
   $height = imagesy($image);
   $newWidth = $width / 2;
   $newHeight = $height / 2;
   $newImage = imagecreatetruecolor($newWidth, $newHeight);
   imagecopyresampled($newImage, $image, 0, 0, 0, 0, $newWidth, $newHeight, $width, $height);

3. imagescale
   This function is also used to change the image size. Unlike imagecopyresampled, it can reduce or enlarge an image to a specified size very easily.
   For example, to reduce an image to half its original size:

   $newImage = imagescale($image, imagesx($image) / 2);

4. imagecreatetruecolor
   This function is used to create an image related to true color and returns an identifier that identifies this Image resources.
   For example, to create a 100x100 pixel red image:

   $newImage = imagecreatetruecolor(100, 100);
   $red = imagecolorallocate($newImage, 255, 0, 0);
   imagefill($newImage, 0, 0, $red);

5. imagettftext
   This function is used to draw a text string into an image.
   For example, draw a string to an image:

   $text = "PHP Image Processing";
   $font = 20;
   $angle = 0;
   $x = 50;
   $y = 50;
   $black = imagecolorallocate($newImage, 0, 0, 0);
   imagettftext($newImage, $font, $angle, $x, $y, $black, 'arial.ttf', $text);

6. imagedestroy
   This function is used to destroy an image resource and release the memory associated with it.
   For example, destroy an image resource:

   imagedestroy($image);

The above functions are only a small part of the PHP image processing functions. If you need more image processing functions, you can check the PHP official documentation or use other third-party libraries to complete your tasks. No matter what functionality you need, there are many libraries to choose from in PHP.

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