浅谈关于PHP解决图片无损压缩的问题
本文介绍了关于PHP解决图片无损压缩的问题,分享给大家,具体如下:
代码如下:
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);
我发现用php的imagecopyresized把大图片缩成小图片时,图片会变得很模糊,这时候要提升清晰度不如用imagecopyresampled代替imagecopyresized也许会更好。
注:压缩有损失是必然的,看的清楚与否实际上就是是否接受这个范围的问题.比如你图像上原图有些点是2px,但是你压缩5倍,那么这些点就会消失。
600?600:$width)*0.9; $new_height=($height>600?600:$height)*0.9; switch($type){ case1: $giftype=check_gifcartoon($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; case2: 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; case3: 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($image_wp); break; } } /** *desription判断是否gif动画 *@paramsting$image_file图片路径 *@returnbooleant是f否 */ functioncheck_gifcartoon($image_file){ $fp=fopen($image_file,'rb'); $image_head=fread($fp,1024); fclose($fp); returnpreg_match("/".chr(0x21).chr(0xff).chr(0x0b).'NETSCAPE2.0'."/",$image_head)?false:true; } ?>
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