這篇文章主要介紹了PHP解決圖片無損壓縮的問題,現在分享給大家,也給大家做個參考。
程式碼如下:
header("Content-type: image/jpeg"); $file = "111.jpg"; $percent = 1.5; //图片压缩比 list($width, $height) = getimagesize($file); //获取原图尺寸 //缩放尺寸 $newwidth = $width * $percent; $newheight = $height * $percent; $src_im = imagecreatefromjpeg($file); $dst_im = imagecreatetruecolor($newwidth, $newheight); imagecopyresized($dst_im, $src_im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height); imagejpeg($dst_im); //输出压缩后的图片 imagedestroy($dst_im); imagedestroy($src_im);
#我發現用php的imagecopyresized把大圖片縮成小圖片時,圖片會變得很模糊,這時候要提升清晰度不如用imagecopyresampled 代替imagecopyresized也許會更好。
註:壓縮有損失是必然的,看的清楚與否實際上就是是否接受這個範圍的問題.比如你圖像上原圖有些點是2px,但是你壓縮5倍,那麼這些點就會消失。
<?php /** * desription 压缩图片 * @param sting $imgsrc 图片路径 * @param string $imgdst 压缩后保存路径 */ function image_png_size_add($imgsrc,$imgdst){ list($width,$height,$type)=getimagesize($imgsrc); $new_width = ($width>600?600:$width)*0.9; $new_height =($height>600?600:$height)*0.9; switch($type){ case 1: $giftype=check_gifcartoon($imgsrc); if($giftype){ header('Content-Type:image/gif'); $image_wp=imagecreatetruecolor($new_width, $new_height); $image = imagecreatefromgif($imgsrc); imagecopyresampled($image_wp, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height); imagejpeg($image_wp, $imgdst,75); imagedestroy($image_wp); } break; case 2: header('Content-Type:image/jpeg'); $image_wp=imagecreatetruecolor($new_width, $new_height); $image = imagecreatefromjpeg($imgsrc); imagecopyresampled($image_wp, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height); imagejpeg($image_wp, $imgdst,75); imagedestroy($image_wp); break; case 3: header('Content-Type:image/png'); $image_wp=imagecreatetruecolor($new_width, $new_height); $image = imagecreatefrompng($imgsrc); imagecopyresampled($image_wp, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height); imagejpeg($image_wp, $imgdst,75); imagedestroy($image_wp); break; } } /** * desription 判断是否gif动画 * @param sting $image_file图片路径 * @return boolean t 是 f 否 */ function check_gifcartoon($image_file){ $fp = fopen($image_file,'rb'); $image_head = fread($fp,1024); fclose($fp); return preg_match("/".chr(0x21).chr(0xff).chr(0x0b).'NETSCAPE2.0'."/",$image_head)?false:true; } ?>
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