The perfect solution to low image quality caused by creating thumbnails in PHP

I recently got a forum and asked for a ranking on the homepage to display the list of the top 10 users with the most comments. a thumbnail of the list is the latest File Uploaded By the user. If I use the original image, the picture is too large and the homepage loading is too slow. Therefore, you need to use a thumbnail.
The above uses the imagecopyresized function, which shows poor quality.

Later, the imagecopyresampled effect was significantly changed.

Complete code
[Php]
/**
* @ Name thum thumbnail Function
* @ Param sting $ img_name image path
* @ Param int $ max_width the maximum width of a thumbnail.
* @ Param int $ max_height the maximum height of a thumbnail.
* @ Param sting $ suffix thumbnail suffix (for example, "img_x.jpg" indicates a thumbnail, "img_m.jpg" indicates a graph, and "img_l.jpg" indicates a large image)
* @ Return void
*/
Function thum ($ img_name, $ max_width, $ max_height, $ suffix ){
$ Img_infos = getimagesize ($ img_name );
$ Img_height = $ img_infos [0]; // picture height
$ Img_width = $ img_infos [1]; // Image Width
$ Img_extension = ''; // image suffix
Switch ($ img_infos [2]) {
Case 1:
$ Img_extension = 'gif ';
Break;
Case 2:
$ Img_extension = 'jpeg ';
Break;
Case 3:
$ Img_extension = 'png ';
Break;
Default:
$ Img_extension = 'jpeg ';
Break;
}
$ New_img_size = get_thum_size ($ img_width, $ img_height, $ max_width, $ max_height); // new image size


// Print_r ($ new_img_size );
// Die ('test ');
$ Img_func = ''; // function name
$ Img_handle = ''; // image handle
$ Thum_handle = ''; // a thumbnail image handle
Switch ($ img_extension ){
Case 'jpg ':
$ Img_handle = imagecreatefromjpeg ($ img_name );
$ Img_func = 'imagejpeg ';
Break;
Case 'jpeg ':
$ Img_handle = imagecreatefromjpeg ($ img_name );
$ Img_func = 'imagejpeg ';
Break;
Case 'png ':
$ Img_handle = imagecreatefrompng ($ img_name );
$ Img_func = 'imagepng ';
Break;
Case 'gif ':
$ Img_handle = imagecreatefromgif ($ img_name );
$ Img_func = 'imagegif ';
Break;
Default:
$ Img_handle = imagecreatefromjpeg ($ img_name );
$ Img_func = 'imagejpeg ';
Break;
}
/****/
$ Quality = 100; // Image quality
If ($ img_func === 'imagepng '& (str_replace ('. ', '', PHP_VERSION)> = 512) {// processing of php version changes greater than 5.12
$ Quality = 9;
}
/****/
$ Thum_handle = imagecreatetruecolor ($ new_img_size ['height'], $ new_img_size ['width']);
If (function_exists ('imagecopyresampled ')){
Imagecopyresampled ($ thum_handle, $ img_handle, 0, 0, 0, $ new_img_size ['height'], $ new_img_size ['width'], $ img_height, $ img_width );
} Else {
Imagecopyresized ($ thum_handle, $ img_handle, 0, 0, 0, $ new_img_size ['height'], $ new_img_size ['width'], $ img_height, $ img_width );
}
Call_user_func_array ($ img_func, array ($ thum_handle, get_thum_name ($ img_name, $ suffix), $ quality ));
Imagedestroy ($ thum_handle); // clear the handle
Imagedestroy ($ img_handle); // clear the handle
}
 
/**
* @ Name get_thum_size obtains the size of the thumbnail.
* @ Param $ width: Image width
* @ Param $ height: Image height
* @ Param $ max_width maximum width
* @ Param $ maxHeight maximum height
* @ Param array $ size;
*/
Function get_thum_size ($ width, $ height, $ max_width, $ max_height ){
$ Now_width = $ width; // current width
$ Now_height = $ height; // current height
$ Size = array ();
If ($ now_width> $ max_width) {// if the current width is greater than the maximum width
$ Now_height * = number_format ($ max_width/$ width, 4 );
$ Now_width = $ max_width;
}
If ($ now_height> $ max_height) {// if the current height is greater than the maximum height
$ Now_width * = number_format ($ max_height/$ now_height, 4 );
$ Now_height = $ max_height;
}
$ Size ['width'] = floor ($ now_width );
$ Size ['height'] = floor ($ now_height );
Return $ size;
}
 
/**
* @ Name get_thum_name get the name of the thumbnail (add _ x to the Basic Graph)
*/Www.2cto.com
Function get_thum_name ($ img_name, $ suffix ){
$ Str = explode ('#', $ img_name );
$ Str1 = explode ('.', $ str [1]);
Return $ str [0]. '_'. $ suffix. '.'. $ str1 [1];
}