How to reset image size in php

With the development of today's digital age, people are increasingly inclined to share pictures and videos through the Internet. Therefore, many websites pay great attention to the size of images to ensure that their websites load quickly without affecting the user experience.

PHP is a scripting language widely used in website development. It provides developers with many functions for processing and manipulating images. One of the most commonly used functions is to resize images in PHP.

So, how to reset the image size in PHP? Next, we'll learn some basic methods.

1. Use the imagecopyresampled() function

Imagecopyresampled() is a very useful function for operating images in PHP. By using this we can easily resize the image. The following is the code using this function:

<?php
// 获取原始图片文件
$source_image = imagecreatefromjpeg("原始图片文件路径");

// 声明缩略图的宽度和高度
$thumbnail_width = 150;
$thumbnail_height = 150;

// 声明缩略图图像变量
$thumbnail_image = imagecreatetruecolor($thumbnail_width, $thumbnail_height);

// 将原始图片复制到缩略图图像变量中
imagecopyresampled($thumbnail_image, $source_image, 0, 0, 0, 0, $thumbnail_width, $thumbnail_height, imagesx($source_image), imagesy($source_image));

// 将缩略图保存为新文件
imagejpeg($thumbnail_image, "缩略图文件路径", 90);
?>

In the above code, we first use the imagecreatefromjpeg() function to obtain the original image file, then declare the width and height of the thumbnail, and create it using the imagecreatetruecolor() function Created a new image variable to store the thumbnail. Next, we use the imagecopyresampled() function to copy the original image into a new image variable and save the thumbnail as a new file.

2. Using the imagescale() function

The imagescale() function is another useful function in the PHP GD library for resizing images. Below is the code that uses this function:

<?php
// 获取原始图片文件
$source_image = imagecreatefromjpeg("原始图片文件路径");

// 使用imagescale()函数将图片缩放成指定大小
$thumbnail_image = imagescale($source_image, 150, 150);

// 将缩略图保存为新文件
imagejpeg($thumbnail_image, "缩略图文件路径", 90);
?>

In the above code, we first use the imagecreatefromjpeg() function to get the original image file, and then use the imagescale() function to scale it to the specified size. Finally, we save the thumbnail as a new file.

3. Use the imagecopyresized() function

The imagecopyresized() function is very similar to the imagecopyresampled() function and can be used to resize the image. The following is the code using this function:

<?php
// 获取原始图片文件
$source_image = imagecreatefromjpeg("原始图片文件路径");

// 声明缩略图的宽度和高度
$thumbnail_width = 150;
$thumbnail_height = 150;

// 声明缩略图图像变量
$thumbnail_image = imagecreatetruecolor($thumbnail_width, $thumbnail_height);

// 将原始图片复制到缩略图图像变量中
imagecopyresized($thumbnail_image, $source_image, 0, 0, 0, 0, $thumbnail_width, $thumbnail_height, imagesx($source_image), imagesy($source_image));

// 将缩略图保存为新文件
imagejpeg($thumbnail_image, "缩略图文件路径", 90);
?>

In the above code, we first use the imagecreatefromjpeg() function to obtain the original image file, then declare the width and height of the thumbnail, and create it using the imagecreatetruecolor() function Created a new image variable to store the thumbnail. Next, we use the imagecopyresized() function to copy the original image into a new image variable and save the thumbnail as a new file.

Summary

To resize images in PHP, you can use many different functions and methods, including imagecopyresampled(), imagescale(), and imagecopyresized(). No matter which method you choose, you should always keep in mind that you may lose some image quality by resizing your pictures. Therefore, care should be taken when working with any images to ensure that they are always of high quality.

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