An in-depth introduction to PHP image processing functions: image processing technology of imagecreatefrompng, imagecopyresampled, imagefilter and other functions

Introduction to PHP image processing functions: Image processing technology of imagecreatefrompng, imagecopyresampled, imagefilter and other functions

Abstract: Image processing is very important in Web development and enables us to The web pages are more colorful. This article will introduce in detail the commonly used PHP image processing functions, including the use of functions such as imagecreatefrompng, imagecopyresampled and imagefilter, and give specific code examples.

1. imagecreatefrompng function
   The imagecreatefrompng function is a function in PHP specifically used to create png format image resources. It accepts one parameter, which is the path of the image file to be opened. Examples are as follows:

$source = "input.png"; // 输入图片路径
$image = imagecreatefrompng($source); // 创建png图片资源

2. imagecopyresampled function
   The imagecopyresampled function is used to copy one image to another image and can adjust the copied size. It accepts nine parameters, namely the target image resource, the source image resource, the starting coordinates of the target image, the starting coordinates of the source image, the width and height of the target image, and the width and height of the source image. Examples are as follows:

$source = "input.png"; // 输入图片路径
$image = imagecreatefrompng($source); // 创建png图片资源

$destination = imagecreatetruecolor(200, 200); // 创建目标图片资源
imagecopyresampled($destination, $image, 0, 0, 0, 0, 200, 200, imagesx($image), imagesy($image)); // 将图片复制到目标图片上并调整尺寸

header('Content-Type: image/png'); // 设置HTTP头信息
imagepng($destination);  // 输出目标图片
imagedestroy($destination); // 销毁目标图片资源
imagedestroy($image); // 销毁源图片资源

3. imagefilter function
   The imagefilter function can process various filter effects on images, such as brightness adjustment, contrast adjustment, and hue adjustment. It accepts two parameters, namely the image resource and the type of filter. Examples are as follows:

$source = "input.png"; // 输入图片路径
$image = imagecreatefrompng($source); // 创建png图片资源

imagefilter($image, IMG_FILTER_GRAYSCALE); // 将图片变为灰度图像

header('Content-Type: image/png'); // 设置HTTP头信息
imagepng($image);  // 输出目标图片
imagedestroy($image); // 销毁图片资源

Summary:
This article introduces the commonly used image processing functions in PHP, including the use of imagecreatefrompng, imagecopyresampled and imagefilter functions. These functions can help us realize the reading, copying and processing of filter effects of images. At the same time, specific code examples are given to help readers better understand and apply these functions. I hope this article can help readers use image processing technology more flexibly in Web development.

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