Class: Origami::Filter::CCITTFax

Inherits:
Object
  • Object
show all
Includes:
Origami::Filter
Defined in:
lib/origami/filters/ccitt.rb

Overview

Class representing a Filter used to encode and decode data with CCITT-facsimile compression algorithm.

Defined Under Namespace

Classes: DecodeParms

Constant Summary collapse

EOL = 
codeword('000000000001')
RTC = 
codeword('000000000001' * 6)
WHITE_TERMINAL_ENCODE_TABLE = 
{
    0   => codeword('00110101'),
    1   => codeword('000111'),
    2   => codeword('0111'),
    3   => codeword('1000'),
    4   => codeword('1011'),
    5   => codeword('1100'),
    6   => codeword('1110'),
    7   => codeword('1111'),
    8   => codeword('10011'),
    9   => codeword('10100'),
    10  => codeword('00111'),
    11  => codeword('01000'),
    12  => codeword('001000'),
    13  => codeword('000011'),
    14  => codeword('110100'),
    15  => codeword('110101'),
    16  => codeword('101010'),
    17  => codeword('101011'),
    18  => codeword('0100111'),
    19  => codeword('0001100'),
    20  => codeword('0001000'),
    21  => codeword('0010111'),
    22  => codeword('0000011'),
    23  => codeword('0000100'),
    24  => codeword('0101000'),
    25  => codeword('0101011'),
    26  => codeword('0010011'),
    27  => codeword('0100100'),
    28  => codeword('0011000'),
    29  => codeword('00000010'),
    30  => codeword('00000011'),
    31  => codeword('00011010'),
    32  => codeword('00011011'),
    33  => codeword('00010010'),
    34  => codeword('00010011'),
    35  => codeword('00010100'),
    36  => codeword('00010101'),
    37  => codeword('00010110'),
    38  => codeword('00010111'),
    39  => codeword('00101000'),
    40  => codeword('00101001'),
    41  => codeword('00101010'),
    42  => codeword('00101011'),
    43  => codeword('00101100'),
    44  => codeword('00101101'),
    45  => codeword('00000100'),
    46  => codeword('00000101'),
    47  => codeword('00001010'),
    48  => codeword('00001011'),
    49  => codeword('01010010'),
    50  => codeword('01010011'),
    51  => codeword('01010100'),
    52  => codeword('01010101'),
    53  => codeword('00100100'),
    54  => codeword('00100101'),
    55  => codeword('01011000'),
    56  => codeword('01011001'),
    57  => codeword('01011010'),
    58  => codeword('01011011'),
    59  => codeword('01001010'),
    60  => codeword('01001011'),
    61  => codeword('00110010'),
    62  => codeword('00110011'),
    63  => codeword('00110100')
}
WHITE_TERMINAL_DECODE_TABLE = 
WHITE_TERMINAL_ENCODE_TABLE.invert
BLACK_TERMINAL_ENCODE_TABLE = 
{
    0   => codeword('0000110111'),
    1   => codeword('010'),
    2   => codeword('11'),
    3   => codeword('10'),
    4   => codeword('011'),
    5   => codeword('0011'),
    6   => codeword('0010'),
    7   => codeword('00011'),
    8   => codeword('000101'),
    9   => codeword('000100'),
    10  => codeword('0000100'),
    11  => codeword('0000101'),
    12  => codeword('0000111'),
    13  => codeword('00000100'),
    14  => codeword('00000111'),
    15  => codeword('000011000'),
    16  => codeword('0000010111'),
    17  => codeword('0000011000'),
    18  => codeword('0000001000'),
    19  => codeword('00001100111'),
    20  => codeword('00001101000'),
    21  => codeword('00001101100'),
    22  => codeword('00000110111'),
    23  => codeword('00000101000'),
    24  => codeword('00000010111'),
    25  => codeword('00000011000'),
    26  => codeword('000011001010'),
    27  => codeword('000011001011'),
    28  => codeword('000011001100'),
    29  => codeword('000011001101'),
    30  => codeword('000001101000'),
    31  => codeword('000001101001'),
    32  => codeword('000001101010'),
    33  => codeword('000001101011'),
    34  => codeword('000011010010'),
    35  => codeword('000011010011'),
    36  => codeword('000011010100'),
    37  => codeword('000011010101'),
    38  => codeword('000011010110'),
    39  => codeword('000011010111'),
    40  => codeword('000001101100'),
    41  => codeword('000001101101'),
    42  => codeword('000011011010'),
    43  => codeword('000011011011'),
    44  => codeword('000001010100'),
    45  => codeword('000001010101'),
    46  => codeword('000001010110'),
    47  => codeword('000001010111'),
    48  => codeword('000001100100'),
    49  => codeword('000001100101'),
    50  => codeword('000001010010'),
    51  => codeword('000001010011'),
    52  => codeword('000000100100'),
    53  => codeword('000000110111'),
    54  => codeword('000000111000'),
    55  => codeword('000000100111'),
    56  => codeword('000000101000'),
    57  => codeword('000001011000'),
    58  => codeword('000001011001'),
    59  => codeword('000000101011'),
    60  => codeword('000000101100'),
    61  => codeword('000001011010'),
    62  => codeword('000001100110'),
    63  => codeword('000001100111')
}
BLACK_TERMINAL_DECODE_TABLE = 
BLACK_TERMINAL_ENCODE_TABLE.invert
WHITE_CONFIGURATION_ENCODE_TABLE = 
{
    64    => codeword('11011'),
    128   => codeword('10010'),
    192   => codeword('010111'),
    256   => codeword('0110111'),
    320   => codeword('00110110'),
    384   => codeword('00110111'),
    448   => codeword('01100100'),
    512   => codeword('01100101'),
    576   => codeword('01101000'),
    640   => codeword('01100111'),
    704   => codeword('011001100'),
    768   => codeword('011001101'),
    832   => codeword('011010010'),
    896   => codeword('011010011'),
    960   => codeword('011010100'),
    1024  => codeword('011010101'),
    1088  => codeword('011010110'),
    1152  => codeword('011010111'),
    1216  => codeword('011011000'),
    1280  => codeword('011011001'),
    1344  => codeword('011011010'),
    1408  => codeword('011011011'),
    1472  => codeword('010011000'),
    1536  => codeword('010011001'),
    1600  => codeword('010011010'),
    1664  => codeword('011000'),
    1728  => codeword('010011011'),

    1792  => codeword('00000001000'),
    1856  => codeword('00000001100'),
    1920  => codeword('00000001001'),
    1984  => codeword('000000010010'),
    2048  => codeword('000000010011'),
    2112  => codeword('000000010100'),
    2176  => codeword('000000010101'),
    2240  => codeword('000000010110'),
    2340  => codeword('000000010111'),
    2368  => codeword('000000011100'),
    2432  => codeword('000000011101'),
    2496  => codeword('000000011110'),
    2560  => codeword('000000011111')
}
WHITE_CONFIGURATION_DECODE_TABLE = 
WHITE_CONFIGURATION_ENCODE_TABLE.invert
BLACK_CONFIGURATION_ENCODE_TABLE = 
{
    64    => codeword('0000001111'),
    128   => codeword('000011001000'),
    192   => codeword('000011001001'),
    256   => codeword('000001011011'),
    320   => codeword('000000110011'),
    384   => codeword('000000110100'),
    448   => codeword('000000110101'),
    512   => codeword('0000001101100'),
    576   => codeword('0000001101101'),
    640   => codeword('0000001001010'),
    704   => codeword('0000001001011'),
    768   => codeword('0000001001100'),
    832   => codeword('0000001001101'),
    896   => codeword('0000001110010'),
    960   => codeword('0000001110011'),
    1024  => codeword('0000001110100'),
    1088  => codeword('0000001110101'),
    1152  => codeword('0000001110110'),
    1216  => codeword('0000001110111'),
    1280  => codeword('0000001010010'),
    1344  => codeword('0000001010011'),
    1408  => codeword('0000001010100'),
    1472  => codeword('0000001010101'),
    1536  => codeword('0000001011010'),
    1600  => codeword('0000001011011'),
    1664  => codeword('0000001100100'),
    1728  => codeword('0000001100101'),

    1792  => codeword('00000001000'),
    1856  => codeword('00000001100'),
    1920  => codeword('00000001001'),
    1984  => codeword('000000010010'),
    2048  => codeword('000000010011'),
    2112  => codeword('000000010100'),
    2176  => codeword('000000010101'),
    2240  => codeword('000000010110'),
    2340  => codeword('000000010111'),
    2368  => codeword('000000011100'),
    2432  => codeword('000000011101'),
    2496  => codeword('000000011110'),
    2560  => codeword('000000011111')
}
BLACK_CONFIGURATION_DECODE_TABLE = 
BLACK_CONFIGURATION_ENCODE_TABLE.invert

Constants included from Origami::Filter

A85, AHx, CCF, Fl, RL

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Origami::Filter

included

Constructor Details

#initialize(parameters = {}) ⇒ CCITTFax

Creates a new CCITT Fax Filter.



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# File 'lib/origami/filters/ccitt.rb', line 290

def initialize(parameters = {})
    super(DecodeParms.new(parameters))
end

Class Method Details

.codeword(str) ⇒ Object

:nodoc:



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# File 'lib/origami/filters/ccitt.rb', line 50

def self.codeword(str) #:nodoc:
    [ str.to_i(2), str.length ]
end

Instance Method Details

#decode(stream) ⇒ Object

Decodes data using CCITT-facsimile compression method.



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# File 'lib/origami/filters/ccitt.rb', line 343

def decode(stream)
    mode = @params.has_key?(:K) ? @params.K.value : 0

    unless mode.is_a?(::Integer) and mode <= 0
        raise NotImplementedError.new("CCITT encoding scheme not supported", input_data: stream)
    end

    columns = @params.has_key?(:Columns) ? @params.Columns.value : 1728
    unless columns.is_a?(::Integer) and columns > 0 #and columns % 8 == 0
        raise CCITTFaxFilterError.new("Invalid value for parameter `Columns'", input_data: stream)
    end

    colors = (@params.BlackIs1 == true) ? [0,1] : [1,0]
    white, _black = colors
    params =
    {
        is_aligned?: (@params.EncodedByteAlign == true),
        has_eob?: (@params.EndOfBlock.nil? or @params.EndOfBlock == true),
        has_eol?: (@params.EndOfLine == true)
    }

    unless params[:has_eob?]
        unless @params.has_key?(:Rows) and @params.Rows.is_a?(::Integer) and @params.Rows.value > 0
            raise CCITTFaxFilterError.new("Invalid value for parameter `Rows'", input_data: stream)
        end

        rows = @params.Rows.to_i
    end

    bitr = Utils::BitReader.new(stream)
    bitw = Utils::BitWriter.new

    # Group 4 requires an imaginary white line
    if mode < 0
        prev_line = Utils::BitWriter.new
        write_bit_range(prev_line, white, columns)
        prev_line = Utils::BitReader.new(prev_line.final.to_s)
    end

    until bitr.eod? or rows == 0
        # realign the read line on a 8-bit boundary if required
        if params[:is_aligned?] and bitr.pos % 8 != 0
            bitr.pos += 8 - (bitr.pos % 8)
        end

        # received return-to-control code
        if params[:has_eob?] and bitr.peek(RTC[1]) == RTC[0]
            bitr.pos += RTC[1]
            break
        end

        # checking for the presence of EOL
        if bitr.peek(EOL[1]) != EOL[0]
            raise InvalidCCITTFaxDataError.new(
                    "No end-of-line pattern found (at bit pos #{bitr.pos}/#{bitr.size}})",
                    input_data: stream,
                    decoded_data: bitw.final.to_s
            ) if params[:has_eol?]
        else
            bitr.pos += EOL[1]
        end

        begin
            case
            when mode == 0
                decode_one_dimensional_line(bitr, bitw, columns, colors)
            when mode < 0
                decode_two_dimensional_line(bitr, bitw, columns, colors, prev_line)
            end
        rescue DecodeError => error
            error.input_data = stream
            error.decoded_data = bitw.final.to_s

            raise error
        end


        rows -= 1 unless params[:has_eob?]
    end

    bitw.final.to_s
end

#encode(stream) ⇒ Object

Encodes data using CCITT-facsimile compression method.



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# File 'lib/origami/filters/ccitt.rb', line 297

def encode(stream)
    mode = @params.has_key?(:K) ? @params.K.value : 0

    unless mode.is_a?(::Integer) and mode <= 0
        raise NotImplementedError.new("CCITT encoding scheme not supported", input_data: stream)
    end

    columns = @params.has_key?(:Columns) ? @params.Columns.value : (stream.size << 3)
    unless columns.is_a?(::Integer) and columns > 0 #and columns % 8 == 0
        raise CCITTFaxFilterError.new("Invalid value for parameter `Columns'", input_data: stream)
    end

    if stream.size % (columns >> 3) != 0
        raise CCITTFaxFilterError.new("Data size is not a multiple of image width", input_data: stream)
    end

    colors = (@params.BlackIs1 == true) ? [0,1] : [1,0]
    white, _black = colors
    bitr = Utils::BitReader.new(stream)
    bitw = Utils::BitWriter.new

    # Group 4 requires an imaginary white line
    if mode < 0
        prev_line = Utils::BitWriter.new
        write_bit_range(prev_line, white, columns)
        prev_line = Utils::BitReader.new(prev_line.final.to_s)
    end

    until bitr.eod?
        case
        when mode == 0
            encode_one_dimensional_line(bitr, bitw, columns, colors)
        when mode < 0
            encode_two_dimensional_line(bitr, bitw, columns, colors, prev_line)
        end
    end

    # Emit return-to-control code
    bitw.write(*RTC)

    bitw.final.to_s
end