Class: Bmp

Inherits:
Object
  • Object
show all
Defined in:
lib/bmp.rb

Overview

This class contains the methods to read bmp files It supports 1,2,4,8,16,24 bits per pixel and RLE compression

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(path) ⇒ Bmp

getters



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# File 'lib/bmp.rb', line 11

def initialize(path)
  puts "Inside bmp constructor"
  file_descriptor = IO.sysopen(path)
  @raw_data = IO.new(file_descriptor)
  @signature = @raw_data.sysread(2)
  @size = @raw_data.sysread(4).unpack('L')[0] # Because little endian format
  @raw_data.sysseek(10)
  @offset = @raw_data.sysread(4).unpack('L')[0]
  @info_header_size = @raw_data.sysread(4).unpack('L')[0]
  @width = @raw_data.sysread(4).unpack('L')[0]
  @height = @raw_data.sysread(4).unpack('L')[0]
  @planes = @raw_data.sysread(2).unpack('S')[0]
  @bits_per_pixel = @raw_data.sysread(2).unpack('S')[0]
  @numcolors = 2**@bits_per_pixel
  @compression = @raw_data.sysread(4).unpack('L')[0]
  @compressed_size = @raw_data.sysread(4).unpack('L')[0]
  @x_pixels_per_m = @raw_data.sysread(4).unpack('L')[0]
  @y_pixels_per_m = @raw_data.sysread(4).unpack('L')[0]
  @colors_used = @raw_data.sysread(4).unpack('L')[0]
  @num_of_imp_colors = @raw_data.sysread(4).unpack('L')[0]
  read_to_palette if @bits_per_pixel <= 8
  read_masks if @bits_per_pixel >= 16
  puts @raw_data.pos.to_s
end

Instance Attribute Details

#height ⇒ Object (readonly)

Returns the value of attribute height.



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# File 'lib/bmp.rb', line 49

def height
  @height
end

#width ⇒ Object (readonly)

IO.write(“results/palette.txt”, @palette.join(“n”))



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# File 'lib/bmp.rb', line 48

def width
  @width
end

Class Method Details

.populate_colors(array) ⇒ Object 



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# File 'lib/bmp.rb', line 353

def self.populate_colors(array)
  colors = Hash.new
  height = array.length
  #raise exception if empty array
  width = array[0].length
  index = 0
  #creating a hashmap of unique colors for palette
  (1...height).each do |i|
    (1...width).each do |j|
      #debug
      #if(array[i][j].class.to_s != "Array")
      #  puts "******"
      #  puts array[i][j]
      #  puts i
      #  puts j
      #  puts "******"
      #end
      if(colors.key?(array[i][j]))
        next
      else
        colors.store(array[i][j], index)
        index += 1
      end
      if(index > 255)
        print "ERROR"
        return
        #raise exception

      end
    end
  end
  colors
end

.write_to_bmp(name, array, bpp, compression_type) ⇒ Object 



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# File 'lib/bmp.rb', line 387

def self.write_to_bmp(name, array, bpp, compression_type)
  height = array.length
  #raise exception if empty array
  width = array[0].length
  filestep = ((width*3 + 3) & -(4))
  zeropad = "\0\0\0\0"
  bmp_header_size = 40

  if(bpp<=8)
    palette_size = 1024
    header_size = 14 + bmp_header_size + palette_size
    ############
    colors = populate_colors(array)
    
    (1..colors.length).each do |i|
      puts colors.keys[i-1].length

    end
    ####debug###
    #IO.write("palette2.txt", colors)
    ############
    file_size = height*filestep

    fileEntity = File.new(name, "w")
    if fileEntity
      size = [file_size+header_size]
      offset = [54+1024]
      x_pixels_per_m = 2000
      y_pixels_per_m = 2000
      fileEntity.syswrite([19778].pack('S')) #signature - "BM"
      fileEntity.syswrite(size.pack('L')) #size
      fileEntity.syswrite([0].pack('L')) #random 4 bytes ###check if accounting for palette
      fileEntity.syswrite(offset.pack('L')) #offset
      fileEntity.syswrite([bmp_header_size].pack('L')) #header size
      fileEntity.syswrite([width].pack('L')) #width
      fileEntity.syswrite([height].pack('L')) #height
      fileEntity.syswrite([1].pack('S')) #planes
      fileEntity.syswrite([bpp].pack('S')) #bits per pixel
      fileEntity.syswrite([compression_type].pack('L')) #compression
      fileEntity.syswrite([0].pack('L')) #compressed size
      fileEntity.syswrite([x_pixels_per_m].pack('L')) #x_pixels_per_m
      fileEntity.syswrite([y_pixels_per_m].pack('L')) #y_pixels_per_m
      fileEntity.syswrite([0].pack('L')) #number of important colors
      fileEntity.syswrite([0].pack('L')) #number of important colors
      (1..colors.length).each do |i| #writes palette
        fileEntity.syswrite([colors.keys[i-1][0]].pack('C')) #b
        fileEntity.syswrite([colors.keys[i-1][1]].pack('C')) #g
        fileEntity.syswrite([colors.keys[i-1][2]].pack('C')) #r
        #fileEntity.syswrite([colors.keys[i-1][3]].pack('C'))
        fileEntity.syswrite([0].pack('C')) #random
      end
      (1..547).each do |i| #writes palette
        fileEntity.syswrite([0].pack('C')) #random
      end
      #starts writing the pixel info
      (1...height).each do |i|
        (1...width).each do |j|
          fileEntity.syswrite([colors[array[height-i][j-1]]].pack('C'))

        end
        (1..((width*2) % 4)).each do
          fileEntity.syswrite([0].pack('C'))
        end
      end
      fileEntity.syswrite([0].pack('C'))
      fileEntity.syswrite([1].pack('C'))
    end
    print "Successfully created bmp file"
  else

  end

end

Instance Method Details

#decompress_RLE4 ⇒ Object 



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# File 'lib/bmp.rb', line 192

def decompress_RLE4
  a = Array.new(height)
  (1..@height).each do |j|
    i = 0
    row_array = []
    len = 0
    loop do

      first_byte = @raw_data.sysread(1).unpack('C')[0]
      second_byte = @raw_data.sysread(1).unpack('C')[0]
      if first_byte != 0
        pixel_two = second_byte & 15
        pixel_one = second_byte >> 4
        rolling_array = [pixel_one, pixel_two]
        k = 0
        (1..first_byte).each do
          row_array.push(@palette[rolling_array[k]])
          k = k ^ 1
          len += 1
        end
      elsif second_byte > 2
        sz = (((second_byte + 1)>>1) + 1) & (~1)
        if second_byte%2 == 1
          temp = 0
          (1..sz).each do
            len += 2
            two_pixels =  @raw_data.sysread(1).unpack('C')[0]
            pixel_two = two_pixels & 15
            pixel_one = two_pixels >> 4
            if temp<second_byte
              row_array.push(@palette[pixel_one])
              temp += 1
            end
            if temp<second_byte
              row_array.push(@palette[pixel_two])
              temp += 1
            end
          end
        else
          (1..sz).each do
            len += 2
            two_pixels =  @raw_data.sysread(1).unpack('C')[0]
            pixel_two = two_pixels & 15
            pixel_one = two_pixels >> 4
            row_array.push(@palette[pixel_one])
            row_array.push(@palette[pixel_two])
          end
        end
      elsif second_byte == 1
        break
      end
      break if len >= @width

    end
    a[@height - j] = row_array
  end
  puts @raw_data.pos.to_s
  return a
end

#decompress_RLE8 ⇒ Object 



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# File 'lib/bmp.rb', line 252

def decompress_RLE8
  a = Array.new(@height)
  @raw_data.sysseek(@offset)
  (1..@height).each do |j|
    i = 0
    row_array = []
    len = 0
    loop do

      first_byte = @raw_data.sysread(1).unpack('C')[0]
      second_byte = @raw_data.sysread(1).unpack('C')[0]
      if first_byte != 0
        (1..first_byte).each do
          row_array.push(@palette[second_byte])
          len += 1
        end
      elsif second_byte > 2
        sz = (second_byte+1) & (~1)

        if second_byte 2 ==1
          (1..(sz-1)).each do
            len += 1
            pixel_val =  @raw_data.sysread(1).unpack('C')[0]
            row_array.push(@palette[pixel_val])
          end
          garbage = @raw_data.sysread(1).unpack('C')[0]
        else
          (1..sz).each do
            len += 1
            pixel_val =  @raw_data.sysread(1).unpack('C')[0]
            row_array.push(@palette[pixel_val])
          end
        end
      elsif second_byte == 1
        #break
      elsif second_byte == 2
        puts "Error"
      end
      break if len >= @width

    end
    a[@height - j] = row_array
  end

  return a
end

#describe ⇒ Object 



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# File 'lib/bmp.rb', line 59

def describe
  puts 'Header Data'
  puts "Signature: #{@signature}"
  puts "Size: #{@size}"
  puts "Offset: #{@offset}"
  puts 'InfoHeader Data'
  puts "Infoheader size: #{@info_header_size}"
  puts "Width: #{@width}"
  puts "Height: #{@height}"
  puts "Planes: #{@planes}"
  puts "Bits per pixel = #{@bits_per_pixel}"
  puts "Compression: #{@compression}"
  if @compression.zero?
    puts 'Compression: None'
  elsif @compression == 1
    puts 'Compression: BI_RLE8 8 bit encoding'
  elsif @compression == 2
    puts 'Compression: BI_RLE4 4 bit encoding'
  elsif @compression == 3
    puts 'Compression: BI_BITFIELDS'
  end
  puts "Compressed image size: #{@compressed_size}"
  puts "Pixel density on x-axis (per m): #{@x_pixels_per_m}"
  puts "Pixel density on y-axis (per m): #{@y_pixels_per_m}"
  puts "Used colors (in color palette): #{@colors_used}"
  puts "Number of important colors: #{@num_of_imp_colors} (0 if all are important)"
end

#read_from_palette ⇒ Object 



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# File 'lib/bmp.rb', line 101

def read_from_palette
  a = Array.new(@height)
  if @bits_per_pixel == 1
    row_length = ((@width / 32).floor * 32 + 32) / 8
    (1..@height).each do |i|
      colors = []
      row_length_data = ''
      (1..row_length).each do
        row_length_data += @raw_data.sysread(1).unpack('C')[0].to_s
      end
      (1..@width).each do |j|
        colors[j - 1] = @palette[row_length_data[j].to_i]
      end
      a[@height - i] = colors
    end
  elsif @bits_per_pixel == 2
    (1..@height).each do |i|
      row_array = []
      row_length = ((@width / 32).floor * 32 + 32) / 8
      count = 0
      (1..row_length).each do |_j|
        break if count > @width

        byteval = @raw_data.sysread(1).unpack('C')[0]
        fourth = byteval & 3
        byteval >> 2
        third = byteval & 3
        byteval >> 2
        second = byteval & 3
        byteval >> 2
        first = byteval
        row_array.push(@palette[first])
        count += 1
        break if count >= @width

        row_array.push(@palette[second])
        count += 1
        break if count >= @width

        row_array.push(@palette[third])
        count += 1
        break if count >= @width

        row_array.push(@palette[fourth])
        count += 1
        break if count >= @width
      end
      a[@height - i] = row_array
    end
  elsif @bits_per_pixel == 4
    if @compression != 0
      a = decompress_RLE4
      return a
    end
    (1..@height).each do |i|
      row_array = []
      row_length = ((@width * 4 / 32).floor * 32 + 32) / 8
      count = 0
      (1..row_length).each do |_j|
        break if count >= @width

        byteval = @raw_data.sysread(1).unpack('C')[0]
        second = byteval & 15
        byteval >> 4
        first = byteval
        row_array.push(@palette[first])
        count += 1
        break if count >= @width

        row_array.push(@palette[second])
        count += 1
      end
      a[@height - i] = row_array
    end
  elsif @bits_per_pixel == 8
    if @compression != 0
      a = decompress_RLE8
      return a
    end
    (1..@height).each do |i|
      row_array = Array.new(@width)
      (1..@width).each do |j|
        row_array[j - 1] = @palette[@raw_data.sysread(1).unpack('C')[0]]
      end
      @raw_data.sysread((@width * 3) % 4) # zeros are appended to rows of pixels if the image width is not a multiple of 4, this ignores them.
      a[@height - i] = row_array
    end
  end
  a
end

#read_from_pixel_array ⇒ Object 



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# File 'lib/bmp.rb', line 299

def read_from_pixel_array
  a = Array.new(@height)
  if @bits_per_pixel == 16 # works for rgb555 format, not rgb565
    (1..@height).each do |i|
      row_array = Array.new(@width)
      (1..@width).each do |j|
        bindata = @raw_data.sysread(2).unpack('S')[0]
        #bindata = bindata>>1
        b = (bindata<<3) & 0xf8

        g = (bindata>>2) & 0xf8
        #bindata = bindata >> 6
        r = (bindata>>7) & 0xf8
        row_array[j - 1] = [b, g, r]
      end
      @raw_data.sysread((@width * 3) % 4) # zeros are appended to rows of pixels if the image width is not a multiple of 4, this ignores them.
      a[@height - i] = row_array
    end

  elsif @bits_per_pixel == 24
    (1..@height).each do |i|
      row_array = Array.new(@width)
      (1..@width).each do |j|
        b = @raw_data.sysread(1).unpack('C')[0]
        g = @raw_data.sysread(1).unpack('C')[0]
        r = @raw_data.sysread(1).unpack('C')[0]
        row_array[j - 1] = [b, g, r]
      end
      @raw_data.sysread((@width * 3) % 4) # zeros are appended to rows of pixels if the image width is not a multiple of 4, this ignores them.
      a[@height - i] = row_array
    end
  elsif @bits_per_pixel == 32 # not tested with an image yet, maybe order of colors is wrong
    (1..@height).each do |i|
      row_array = Array.new(@width)
      (1..@width).each do |j|
        b = @raw_data.sysread(1).unpack('C')[0]
        g = @raw_data.sysread(1).unpack('C')[0]
        r = @raw_data.sysread(1).unpack('C')[0]
        alpha = @raw_data.sysread(1).unpack('C')[0]
        row_array[j - 1] = [ b, g, r, alpha] # should be changed based on requirement
      end
      @raw_data.sysread((@width * 3) % 4) # zeros are appended to rows of pixels if the image width is not a multiple of 4, this ignores them.
      a[@height - i] = row_array
    end
  end
  a
end

#read_masks ⇒ Object 



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# File 'lib/bmp.rb', line 50

def read_masks
  if @compression != 0
    @redmask = @raw_data.sysread(4).unpack('N')[0]
    @greenmask = @raw_data.sysread(4).unpack('N')[0]
    @bluemask = @raw_data.sysread(4).unpack('N')[0]
    @alphachannel = @raw_data.sysread(4).unpack('N')[0]
  end
end

#read_to_array ⇒ Object 



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# File 'lib/bmp.rb', line 87

def read_to_array
  @raw_data.sysseek(@offset)
  a = Array.new(@height)

  if @bits_per_pixel <= 8
    a = read_from_palette
  elsif @bits_per_pixel > 8
    a = read_from_pixel_array
    # puts "Location of pointer after reading: #{@raw_data.pos}"
  end

  a
end

#read_to_nmatrix ⇒ Object

will do once the bug is fixed



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# File 'lib/bmp.rb', line 348

def read_to_nmatrix
  result = [] # NMatrix.new([3, 3],dtype: :int64)
  result
end

#read_to_palette ⇒ Object 



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# File 'lib/bmp.rb', line 36

def read_to_palette
  @palette = []
  (1..@colors_used).each do |i|
    b = @raw_data.sysread(1).unpack('C')[0]
    g = @raw_data.sysread(1).unpack('C')[0]
    r = @raw_data.sysread(1).unpack('C')[0]
    temp = @raw_data.sysread(1).unpack('C')
    @palette[i - 1] = [b, g, r]
    #puts "#{r},#{g},#{b}"
  end
  #IO.write("results/palette.txt", @palette.join("\n"))
end