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tiffdither(1)                        LibTIFF                       tiffdither(1)




NAME

       tiffdither - convert a greyscale TIFF image to bilevel using dithering


SYNOPSIS

       tiffdither [ options ] input.tif output.tif


DESCRIPTION

       tiffdither converts a single channel 8-bit greyscale image to a bilevel
       image using Floyd-Steinberg error propagation with thresholding.


OPTIONS


       -c compress
              Specify the compression to use for data written to the output
              file:

                           +------------+-------------------------+
                           |Compression | Description             |
                           +------------+-------------------------+
                           |none        | no compression          |
                           +------------+-------------------------+
                           |packbits    | PackBits compression    |
                           +------------+-------------------------+
                           |lzw         | Lempel-Ziv & Welch      |
                           |            | compression             |
                           +------------+-------------------------+
                           |zip         | Deflate compression     |
                           +------------+-------------------------+
                           |g3          | CCITT Group 3 (T.4)     |
                           |            | compression             |
                           +------------+-------------------------+
                           |g4          | for CCITT Group 4 (T.6) |
                           |            | compression             |
                           +------------+-------------------------+

              By default tiffdither will compress data according to the value of
              the Compression tag found in the source file.

              The CCITT Group 3 and Group 4 compression algorithms can only be
              used with bilevel data.

              Group 3 compression can be specified together with several
              T.4-specific options: 1d for 1-dimensional encoding, 2d for
              2-dimensional encoding, and fill to force each encoded scanline to
              be zero-filled so that the terminating EOL code lies on a byte
              boundary.  Group 3-specific options are specified by appending a
              :-separated list to the g3 option; e.g. -c g3:2d:fill to get
              2D-encoded data with byte-aligned EOL codes.

              LZW compression can be specified together with a predictor value.
              A predictor value of 2 causes each scanline of the output image to
              undergo horizontal differencing before it is encoded; a value of 1
              forces each scanline to be encoded without differencing.
              LZW-specific options are specified by appending a :-separated list
              to the lzw option; e.g. -c lzw:2 for LZW compression with
              horizontal differencing.

       -f     Specify the bit fill order to use in writing output data.  By
              default, tiffdither will create a new file with the same fill
              order as the original.  Specifying -f lsb2msb will force data to
              be written with the FillOrder tag set to LSB2MSB, while -f msb2lsb
              will force data to be written with the FillOrder tag set to
              MSB2LSB.

       -r     Make each strip have no more than the given number of rows.

       -t     Set the threshold value for dithering.  By default the threshold
              value is 128.


NOTES

       The dither algorithm is taken from the tiffmedian program (written by
       Paul Heckbert).


SEE ALSO

       pal2rgb(1), fax2tiff(1), tiffinfo(1), tiffcp(1), tiff2bw(3)


AUTHOR

       LibTIFF contributors


COPYRIGHT

       1988-2022, LibTIFF contributors



4.5                             December 23, 2022                  tiffdither(1)

tiff 4.5.0 - Generated Sat Dec 24 13:05:01 CST 2022
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