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TIFFMEDIAN

NAME

SYNOPSIS

DESCRIPTION

OPTIONS

NOTES

SEE ALSO

NAME

       cols="2" cellspacing="0" cellpadding="0">

tiffmedian − apply the median cut algorithm to data

in a <small>TIFF</small> file

SYNOPSIS

       cols="2" cellspacing="0" cellpadding="0">

tiffmedian [ options ] input.tif

output.tif

DESCRIPTION

       cols="2" cellspacing="0" cellpadding="0">

tiffmedian applies the median cut algorithm to an

<small>RGB</small> image in input.tif to generate a

palette image that is written to output.tif. The

generated colormap has, by default, 256 entries. The image

data is quantized by mapping each pixel to the closest color

values in the colormap.

OPTIONS

       cols="5" cellspacing="0" cellpadding="0">

−c

Specify the compression to use for data written to the

output file: none for no compression, packbits

for PackBits compression, lzw for Lempel-Ziv &

Welch compression, and zip for Deflate compression.

By default tiffmedian will compress data according to

the value of the Compression tag found in the source

file.

       cols="2" cellspacing="0" cellpadding="0">

<small>LZW</small> 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 <small>LZW</small> compression with horizontal

differencing.

       cols="5" cellspacing="0" cellpadding="0">

−C

Specify the number of entries to use in the generated

colormap. By default all 256 entries/colors are used.

−f

Apply Floyd-Steinberg dithering before selecting a

colormap entry.

−r

Specify the number of rows (scanlines) in each strip of

data written to the output file. By default,

tiffmedian attempts to set the rows/strip that no

more than 8 kilobytes of data appear in a strip.

NOTES

       cols="2" cellspacing="0" cellpadding="0">

This program is derived from Paul Heckbert’s

median program.

SEE ALSO

       cols="2" cellspacing="0" cellpadding="0">

pal2rgb(1), tiffinfo(1), tiffcp(1),

tiffcmp(1), libtiff(3TIFF)

Color Image Quantization for Frame Buffer Display,

Paul Heckbert, SIGGRAPH proceedings, 1982, pp. 297-307.

Libtiff library home page:

http://www.remotesensing.org/libtiff/