How to process images using PHP built-in functions?

PHP built-in functions provide convenient image processing functions, which can realize image scaling, cropping, adding watermarks and other operations. Use imagecopyresampled() to resize the image, imagecrop() to crop the image, and imagecopymerge() to add a watermark.

How to use PHP built-in functions to process images

PHP provides a wealth of built-in functions for image processing, allowing you to operate images conveniently and quickly. This article will introduce how to use these functions to perform common operations on images, including scaling, cropping, adding watermarks, etc. The following content includes actual case code.

Scale the image

imagecopyresampled() The function can scale the image:

<?php
$src_image = 'image.jpg';
$dst_image = 'image-scaled.jpg';
$scaled_width = 300;
$scaled_height = 200;

$src = imagecreatefromjpeg($src_image);
$dst = imagecreatetruecolor($scaled_width, $scaled_height);
imagecopyresampled($dst, $src, 0, 0, 0, 0, $scaled_width, $scaled_height, imagesx($src), imagesy($src));
imagejpeg($dst, $dst_image);
?>

Crop the image

imagecrop() Function can crop the image:

<?php
$src_image = 'image.jpg';
$dst_image = 'image-cropped.jpg';
$crop_x = 100;
$crop_y = 200;
$crop_width = 300;
$crop_height = 200;

$src = imagecreatefromjpeg($src_image);
$dst = imagecrop($src, ['x' => $crop_x, 'y' => $crop_y, 'width' => $crop_width, 'height' => $crop_height]);
imagejpeg($dst, $dst_image);
?>

Add watermark

imagecopymerge() Function Watermark can be added:

<?php
$main_image = 'image.jpg';
$watermark_image = 'watermark.png';
$output_image = 'image-with-watermark.jpg';
$margin = 50;

$main = imagecreatefromjpeg($main_image);
$watermark = imagecreatefrompng($watermark_image);

$watermark_width = imagesx($watermark);
$watermark_height = imagesy($watermark);

$dst_x = imagesx($main) - $margin - $watermark_width;
$dst_y = imagesy($main) - $margin - $watermark_height;

imagecopymerge($main, $watermark, $dst_x, $dst_y, 0, 0, $watermark_width, $watermark_height, 75);
imagejpeg($main, $output_image);
?>

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