require 'RMagick' img = Magick::Image.read("images/Flower_Hat.jpg").first begin img = img.level_colors("green", "orange", true) img.alpha(Magick::DeactivateAlphaChannel) rescue NotImplementedError not_imp = Magick::Image.read('images/notimplemented.gif').first img = not_imp.resize(img.columns, img.rows) end img.write("level_colors.jpg")