Usage
{{#invoke:ImageRatio|ratio|Filename.jpg}}
This returns the ratio of width to height (w/h) for an image. Defaults to returning 1 if the image doesn't exist, this avoids divide by 0 errors in templates that use it.
local p={}
function p.ratio(frame)
local file = frame.args[1] and mw.title.new('File:' .. mw.uri.decode(mw.ustring.gsub(frame.args[1],'%|.*$',''), 'WIKI'))
file = file and file.file
local w = tonumber(file.width) or 1
local h = tonumber(file.height) or 1
local r = w/h or 1
return r
end
return p