Question

I’m using imagecreatefromjpeg(), imagecreatefrompng() and imagecreatefromgif() to convert some image files and want to know the filesize of the image after conversion. I’ve tried filesize(imagecreatefrompng(filename)) and getimagesize() – but none of them seem to work. Is there another way?

Answer 1

filesize() and getimagesize() expect a filename. imagecreatefromwhatever() returns a GD file handle. You cannot feed one into the other. You’d need to save your image to a file, then use filesize on that new file, or use the output buffering mechanism to capture the output of the save functions and do a strlen on that, e.g.

$handle = imagecreatefromgif('original.gif');
imagepng($handle, 'new.png');
$size = filesize('new.png');

or

$handle = imagecreatefromgif('original.gif');
ob_start();
imagepng($handle);
$png = ob_get_clean();
$size = strlen($png);

There is no other practical method to determine the final image size WITHOUT producing that file in the first place – PNG/JPG output compression depends heavily on the content of the image – “simple” images will compress far more than “busy” images.