ns_imgsize - Determine the width and height of a JPEG, GIF or PNG image
Returns a list of two elements, the width and height of the file specified by filename. Currently files of type JPEG, GIF or PNG are supported. An error is generated if the file does not exist. If the filetype is not supported the resulting list returns width and height set to 0 (Whereas ns_jpegsize, ns_gifsize and ns_pngsize would generate an error).
% ns_imgsize screenshot.jpg 1024 768
% file exists test.html 1 % ns_imgsize test.html 0 0