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

A perfect solution for low image quality caused by creating thumbnails in PHP. Recently, a forum will be created. The top 10 users with the most comments will be listed on the homepage, A thumbnail in the list is the latest file uploaded by the user. if the original image is used, the image is too large and the homepage loading is too slow, therefore, it is necessary to use a thumbnail or above to use imagecopyresized. This function is a perfect solution for PHP to create thumbnails, resulting in low image quality.

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

/*** @ Namethum thumbnail function * @ paramsting $ img_name Image path * @ paramint $ max_width the maximum width of a thumbnail * @ paramint $ max_height the maximum height of a thumbnail * @ paramsting $ suffix the suffix of a thumbnail (for example "img_x.jpg" indicates a thumbnail, "img_m.jpg" indicates the graph, "img_l.jpg" indicates the big image. * @ returnvoid */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]; // Picture width $ img_extension = ''; // Picture extension name 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 = ''; // skip graph 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 = hour ($ 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 status after the php version is greater than 5.12 parameter change $ 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 handle}/*** @ name get_thum_size obtain the thumbnail size * @ param $ width image width * @ param $ height image height * @ param $ max_width maximum width * @ param $ maxHeight maximum height * @ paramarray $ size; */function get_thum_size ($ width, $ height, $ max_width, $ max_height) {$ now_width = $ width; // The current width $ now_height = $ height; // the 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 base of the larger graph) */function get_thum_name ($ img_name, $ suffix) {$ str = explode ('#', $ img_name); $ str1 = explode ('. ', $ str [1]); return $ str [0]. '_'. $ suffix. '. '. $ str1 [1];}