# File lib/png/reader.rb, line 51 def self.read_IHDR data, metadata_only = false width, height, bit_depth, color_type, *rest = data.unpack 'N2C5' unless metadata_only then raise ArgumentError, "Wrong bit depth: #{bit_depth}" unless bit_depth == 8 raise ArgumentError, "Wrong color type: #{color_type}" unless color_type == RGBA or color_type = RGB raise ArgumentError, "Unsupported options: #{rest.inspect}" unless rest == [0, 0, 0] end return bit_depth, color_type, width, height end