How to Use PHP to generate image thumbnails

This article mainly introduces how to use PHP to generate image thumbnails. Some common image formats are supported. For more information, see

This article mainly introduces how to use PHP to generate image thumbnails. Some common image formats are supported. For more information, see

Function: jpg, jpeg, gif, png, and bmp image formats are supported. You can scale the image according to the original image proportion. You can select whether to crop the image during image scaling, added image quality control to achieve the highest quality of the thumbnail. The complete class code is as follows:

<? Php/*** function: php class for generating thumbnail slices */class ResizeImage {public $ type; // image type public $ width; // actual width public $ height; // actual height public $ resize_width; // The width public $ resize_height after the change; // The height public $ cut after the change; // whether to cut the image public $ srcimg; // source image public $ dstimg; // target image address public $ im; // temporary image public $ quality; // Image quality function resizeimage ($ img, $ wid, $ hei, $ c, $ dstpath, $ quality = 100) {$ this-> srcimg = $ img; $ this-> resize_width = $ wid; $ this-> resize_heig Ht = $ hei; $ this-> cut = $ c; $ this-> quality = $ quality; $ this-> type = strtolower (substr (strrchr ($ this-> srcimg ,'. '), 1); // The image type $ this-> initi_img (); // initialize the image $ this-> dst_img ($ dstpath ); // target image address @ $ this-> width = imagesx ($ this-> im); @ $ this-> height = imagesy ($ this-> im ); $ this-> newimg (); // generates an image @ ImageDestroy ($ this-> im);} function newimg () {$ resize_ratio = ($ this-> resize_width) /($ this-> resize_height); // ratio of the changed image @ $ ratio = ($ this-> widt H)/($ this-> height); // ratio of the actual image if ($ this-> cut) = '1 ') {// cut image if ($ img_func = 'imagepng '& (str_replace ('. ', '', PHP_VERSION)> = 512) {// processing status after the php version is greater than 5.12 parameter change $ quality = 9 ;} if ($ ratio >=$ resize_ratio) {// high priority $ newimg = imagecreatetruecolor ($ this-> resize_width, $ this-> resize_height); imagecopyresampled ($ newimg, $ this-> im, 0, 0, 0, $ this-> resize_width, $ this-> resize_height, ($ this-> height) * $ resize_ratio ), $ this-> height); image Jpeg ($ newimg, $ this-> dstimg, $ this-> quality);} if ($ ratio <$ resize_ratio) {// width first $ newimg = imagecreatetruecolor ($ this-> resize_width, $ this-> resize_height); imagecopyresampled ($ newimg, $ this-> im, 0, 0, 0, 0, $ this-> resize_width, $ this-> resize_height, $ this-> width, ($ this-> width)/$ resize_ratio); imagejpeg ($ newimg, $ this-> dstimg, $ this-> quality) ;}} else {// if ($ ratio >=$ resize_ratio) {$ newimg = imagecreatetruecolor ($ this-> r Esize_width, ($ this-> resize_width)/$ ratio); imagecopyresampled ($ newimg, $ this-> im, 0, 0, 0, $ this-> resize_width, ($ this-> resize_width)/$ ratio, $ this-> width, $ this-> height); imagejpeg ($ newimg, $ this-> dstimg, $ this-> quality);} if ($ ratio <$ resize_ratio) {@$ newimg = imagecreatetruecolor ($ this-> resize_height) * $ ratio, $ this-> resize_height); @ imagecopyresampled ($ newimg, $ this-> im, 0, 0, 0, ($ this-> resize_height) * $ ratio, $ thi S-> resize_height, $ this-> width, $ this-> height); @ imagejpeg ($ newimg, $ this-> dstimg, $ this-> quality );}}} function initi_img () {// initialize the image if ($ this-> type = 'jpg '| $ this-> type = 'jpeg ') {$ this-> im = imagecreatefromjpeg ($ this-> srcimg);} if ($ this-> type = 'gif ') {$ this-> im = imagecreatefromgif ($ this-> srcimg);} if ($ this-> type = 'png ') {$ this-> im = imagecreatefrompng ($ this-> srcimg);} if ($ this-> type = 'wbm ') {@ $ this-> im = imagecreate Fromwbmp ($ this-> srcimg);} if ($ this-> type = 'bmp ') {$ this-> im = $ this-> ImageCreateFromBMP ($ this-> srcimg) ;}} function dst_img ($ dstpath) {// image target address $ full_length = strlen ($ this-> srcimg); $ type_length = strlen ($ this-> type); $ name_length = $ full_length-$ type_length; $ name = substr ($ this-> srcimg, 0, $ name_length-1); $ this-> dstimg = $ dstpath; // echo $ this-> dstimg ;} function ImageCreateFromBMP ($ filename) {// custom function processing bmp image if (! $ F1 = fopen ($ filename, "rb") returnFALSE; $ FILE = unpack ("vfile_type/Vfile_size/Vreserved/Vbitmap_offset", fread ($ f1, 14 )); if ($ FILE ['file _ type']! = 19778) returnFALSE; $ BMP = unpack ('vheader _ size/Vwidth/Vheight/vplanes/vbits_per_pixel '. '/Vcompression/Vsize_bitmap/Vhoriz_resolution '. '/Vvert_resolution/Vcolors_used/Vcolors_important', fread ($ f1, 40); $ BMP ['color'] = pow (2, $ BMP ['bits _ per_pixel ']); if ($ BMP ['size _ bitmap'] = 0) $ BMP ['size _ bitmap'] = $ FILE ['file _ size']-$ file ['bitmap _ offset']; $ BMP ['bytes _ per_pixel '] = $ BMP ['bits _ per_pixel']/8; $ BMP ['bytes _ per_pixel 2'] = ceil ($ BMP ['bytes _ per_pixel ']); $ BMP ['desc'] = ($ BMP ['width'] * $ BMP ['bytes _ per_pixel ']/4 ); $ BMP ['desc']-= floor ($ BMP ['width'] * $ BMP ['bytes _ per_pixel ']/4 ); $ BMP ['Demo'] = 4-(4 * $ BMP ['Demo']); if ($ BMP ['Demo'] = 4) $ BMP ['desc'] = 0; $ PALETTE = array (); if ($ BMP ['color'] <16777216) {$ PALETTE = unpack ('V '. $ BMP ['colors '], fread ($ f1, $ BMP ['colors'] * 4);} $ IMG = fread ($ f1, $ BMP ['size _ bitmap']); $ VIDE = chr (0); $ res = imagecreatetru Ecolor ($ BMP ['width'], $ BMP ['height']); $ P = 0; $ Y = $ BMP ['height']-1; while ($ Y> = 0) {$ X = 0; while ($ X <$ BMP ['width']) {if ($ BMP ['bits _ per_pixel '] = 24) $ COLOR = unpack ("V", substr ($ IMG, $ P, 3 ). $ VIDE); elseif ($ BMP ['bits _ per_pixel '] = 16) {$ COLOR = unpack ("n", substr ($ IMG, $ P, 2); $ COLOR [1] = $ PALETTE [$ COLOR [1] + 1];} elseif ($ BMP ['bits _ per_pixel '] = 8) {$ COLOR = unpack ("n", $ VIDE. substr ($ IMG, $ P, 1); $ COLOR [1] = $ PALETTE [$ COLOR [1] + 1];} elseif ($ BMP ['bits _ per_pixel '] = 4) {$ COLOR = unpack ("n", $ VIDE. substr ($ IMG, floor ($ P), 1); if ($ P * 2) % 2 = 0) $ COLOR [1] = ($ COLOR [1]> 4); else $ COLOR [1] = ($ COLOR [1] & 0x0F ); $ COLOR [1] = $ PALETTE [$ COLOR [1] + 1];} elseif ($ BMP ['bits _ per_pixel '] = 1) {$ COLOR = unpack ("n", $ VIDE. substr ($ IMG, floor ($ P), 1); if ($ P * 8) % 8 = 0) $ COLOR [1] = $ COLOR [1]> 7; elseif ($ P * 8) % 8 = 1) $ COLOR [1] = ($ COLOR [1] & 0x40)> 6; elseif ($ P * 8) % 8 = 2) $ COLOR [1] = ($ COLOR [1] & 0x20)> 5; Elseif ($ P * 8) % 8 = 3) $ COLOR [1] = ($ COLOR [1] & 0x10)> 4; elseif ($ P * 8) % 8 = 4) $ COLOR [1] = ($ COLOR [1] & 0x8)> 3; elseif ($ P * 8) % 8 = 5) $ COLOR [1] = ($ COLOR [1] & 0x4)> 2; elseif ($ P * 8) % 8 = 6) $ COLOR [1] = ($ COLOR [1] & 0x2)> 1; elseif ($ P * 8) % 8 = 7) $ COLOR [1] = ($ COLOR [1] & 0x1 ); $ COLOR [1] = $ PALETTE [$ COLOR [1] + 1];} elsereturnFALSE; imagesetpixel ($ res, $ X, $ Y, $ COLOR [1]); $ X ++; $ P + = $ BMP ['bytes _ per_pixel '];} $ Y --; $ P + = $ BMP ['Demo'];} fclose ($ f1); return $ Res ;}}?>

The usage code is as follows:

$ Resizeimage = new ResizeImage ('upload/abc.bmp ', '000000', '90', '0', 'upload/xabc.bmp ');

Another powerful PHP image thumbnail class: phpThumb

In addition to scaling images, this class can also convert images into different formats for output (for example, exporting GIF images to PNG formats). Its special features include colors and special effects.

Official Website:

We'll be using phpThumb, the open source PHP script to generate thumbnails on the fly.

Download and extract phpThumb to somewhere in your website folder. Now to use a rounded corner thumbnail of an image, simply use the img tag of HTML with src