RMagick - how do I find out the pixel dimension of an image
rmagick, ruby
Solution
require 'rmagick'
img = Magick::Image.ping( 'demo.png' ).first
width = img.columns
height = img.rows
Note `.ping` method imported from comments. If you need to read the image to process it, then use `Magick::Image.read( 'demo.png' ).first` - the use of `ping` works in this stand-alone code and speeds processing up for some image types where IM can just read a header block. This is useful for cases where you don't need to load the image itself to do work on it.
Problem
How does one find the image width and height in pixels? `image.x_resolution` and `image.y_resolution` both return 0 for some reason.