php - How to determine the size of an image without downloading it (in full)?

Question

I'm looking to get the dimensions, width and height, of a remotely hosted JPG. I have seen how it is possible to do this by downloading the full image.

However, it would be ideal if I could do this by downloading only enough to just get this information.

Typical images are 200K in size and reading in just a few K might at the beginning might be enough for JPGs:

curl_setopt($ch, CURLOPT_RANGE, "0-4096");

For reference, I've followed these answers/comments but to no avail (though they might be on the right track):

• Get image dimensions with Curl
• Alternative to CURLOPT_RANGE to grab a specific section

Has anyone been able to put the pieces together (withor without ImageMagick)?

Answer 1

How about using ImageMagick's ping functionality like this:

identify -ping -format "%wx%h" http://www.google.com/logos/giroux1.jpg
482x142