Raster graphics operations/Ruby: Difference between revisions

each_pixel do |x, y|

case format

when "P3" then ios.print @data[x][y].values.join(" "),"\n"

when "P6" then ios.print @data[x][y].values.pack('C3')

end

def save_as_png(filename)

require 'chunky_png'

#require 'stringio'

stream = StringIO.new("", "r+")

each_pixel {|x, y| stream << self[x, y].values.pack("ccc")}

stream.seek(0)

ChunkyPNG::Canvas.extend(ChunkyPNG::Canvas::StreamImporting)

canvas = ChunkyPNG::Canvas.from_rgb_stream(width, height, stream)

canvas.to_image.save(filename)

bitmap.each_pixel do |x,y|

# read 3 bytes

red, green, blue = case format

when 'P3' then ios.gets.chomp.split

when 'P6' then ios.read(3).unpack('C3')

bitmap[x,y] = RGBColour.new(red, green, blue)

each_pixel do |x,y|

gray[x,y] = self[x,y].to_grayscale

end

def to_blackandwhite

hist = histogram

# find the median luminosity

median = nil

sum = 0

hist.keys.sort.each do |lum|

sum += hist[lum]

if sum > @height * @width / 2

median = lum

break

end

end

# create the black and white image

bw = self.class.new(@width, @height)

each_pixel do |x,y|

bw[x,y] = self[x,y].luminosity < median ? RGBColour::BLACK : RGBColour::WHITE

end

bw

end

def save_as_blackandwhite(filename)

to_blackandwhite.save(filename)

def magnify(factor)

bigger = self.class.new(@width * factor, @height * factor)

each_pixel do |x,y|

colour = self[x,y]

(x*factor .. x*factor + factor-1).each do |xx|

(y*factor .. y*factor + factor-1).each do |yy|

bigger[xx,yy] = colour

end

bigger

###############################################

def histogram

histogram = Hash.new(0)

each_pixel do |x,y|

histogram[self[x,y].luminosity] += 1

histogram

end</lang>