我可以用PHP更改图像文件大小吗？

Question

I made a small function to upload images then show them on my website.

My question is now, can I change the file size of a image, on same time as I upload it?

Take facebook as example. Even large images has a size on like 65kb.

If so, witch function should I use?

Thanks,

Answer 1

use the imagecopyresampled function:

$source_image = imagecreatefromjpeg("youtimagejpg");
$src_w= imagesx($source_image);
$src_h= imagesy($source_image);
$dest_image = imagecreatetruecolor(100, 100); //targeted width and height

imagecopyresampled($dest_image, $source_image, 0, 0, 0, 0, 100, 100, $source_w, $source_h);
imagejpeg($dest_image,NULL,80); 
//Replace null by the path if you want to save on the server, otherwise the image will be sent to the client intead.

If you want to reduce the size of the image without resizing it; use the imagejpeg function (with a low quality factor)

Answer 2

There are next ways to change image size:

1. Convert to another image format.
2. Save image with lossy compression ( http://en.wikipedia.org/wiki/Lossy_compression )
3. Resample image with another width & height ( http://php.net/manual/en/function.imagecopyresampled.php )