class Magick::Image
Public Instance Methods
Creates a simple map of the image of '0's and '1's to STDERR this way you can view your image from the terminal set your terminals font very small, so the image will fit on your screen @param width The width of the image to inspect @param height The height of the image to inspect
# File lib/papirus/rmagick.rb, line 9 def inspect_bitstream(width, height) STDERR.puts to_1_bit_2_color_bw_image(width, height).get_pixels(0, 0, width, height).each_slice(width).map{|row| row.each_slice(8).map{|pixels|pixels.map{|pixel| pixel.blue == 0 ? '1' : '0'}.join}.join(' ')}.join("\n") end
Creates a 1-bit 2-color image of whatever image is loaded image is rescaled to fit the width/height and is placed in the middle @param width width the image should be scaled to @param height height the image should be scaled to
# File lib/papirus/rmagick.rb, line 17 def to_1_bit_2_color_bw_image(width, height) # Resize to fit the screen resized = resize_to_fit(width, height) # Reduce the image to a limited number of colors for a "poster" effect, brings it donw to 4-bit 16 colors posterized = resized.posterize(2) #now, as the display expects a file with all pixels set, we need to extend the image to the display size #if it is smaller in either width or height or both if (posterize.columns != width or posterize.rows != height) # extent fill color posterized.background_color = "#FFFFFF" # calculate necessary translation to center image on background x = (posterized.columns - width) / 2 y = (posterized.rows - height) / 2 # now, 'extent' the image to the correct size with the image centered posterized = posterized.extent(width, height, x, y) end # Now, make grayscale with only 2 colors, b/w, brings it down to 1-bit 2 colors return posterized.quantize(2, Magick::GRAYColorspace) end
As the EPD display needs 1-bit per pixel, which get written as a string to the fuse-fs display file we need to load all the bits together in bytes, and packed those bytes into a string @param width width the image should be scaled to @param height height the image should be scaled to @param inverse wether the image should be made negative
# File lib/papirus/rmagick.rb, line 42 def to_bit_stream(width, height, inverse = false) bytes =[] # First, we convert whatever image we got to a 1-bit 2-color image, # then we traverse over the pixels in byte (8 bits) chucks to create our output bytes to_1_bit_2_color_bw_image(width, height).get_pixels(0, 0, width, height).each_slice(8).map do |pixels| #we create a byte with its bits set to 00000000 byte = 0 0.upto(7) do |bit| #and switch the bit to 1 (or 0 if not inverse) for each pixel if it was white #we have to check pixels[7-bit] as the order is right to left byte |= 1 << bit if (inverse && pixels[7-bit].blue == 65535) || (!inverse && pixels[7-bit].blue == 0) end #and add it to the output byte stream bytes.push(byte) end #now we just need to pack all bytes into a file writable string bytes.pack('C*') end