Lib TIFF Tools

Our basic raster map format will be TIFF. We there for need a TIFF library to handle the images. We use the libtiff-tools C library.

Your find the hear full documentation about the libtiff-tools.

Installation of TIFF Tolls Library.
General TIFF Command Line Tools
TIFF Image Handling Library
- Reading a TIFF File
- Writing a TIFF File

Installation of TIFF Tolls Library.

To install the C library libtiff-tools on a Linux operarting system, we get the package:

   # apt-get install libtiff-tools

The library is provided with several use full command line scripts to handle TIFF images.

General TIFF Command Line Tools

We use the following TIFF command line tools:

bmp2tiff
gif2tiff
ppm2tiff
raw2tiff
iff2bw
tiffinfo
tiffdump
titiffcmp

`bmp2tiff` Converter

With the command bmp2tiff we can convert BMP bitmap images to TIFF. The usage is:

usage: bmp2tiff [options] input.bmp [input2.bmp ...] output.tif
where options are:
 -r #      make each strip have no more than # rows

 -c lzw[:opts]   compress output with Lempel-Ziv & Welch encoding
 -c zip[:opts]   compress output with deflate encoding
 -c jpeg[:opts]compress output with JPEG encoding
 -c packbits   compress output with packbits encoding
 -c none   use no compression algorithm on output

JPEG options:
 #      set compression quality level (0-100, default 75)
 r      output color image as RGB rather than YCbCr
For example, -c jpeg:r:50 to get JPEG-encoded RGB data with 50% comp. quality

LZW and deflate options:
 #      set predictor value
For example, -c lzw:2 to get LZW-encoded data with horizontal differencing
 -o out.tif   write output to out.tif
 -h      this help message

`gif2tiff` Converter

With the command gif2tiff we can convert GIF images to TIFF. The usage ist:

usage: gif2tiff [options] input.gif output.tif
where options are:
 -r #      make each strip have no more than # rows

 -c lzw[:opts]   compress output with Lempel-Ziv & Welch encoding
 -c zip[:opts]   compress output with deflate encoding
 -c packbits   compress output with packbits encoding
 -c none   use no compression algorithm on output

LZW and deflate options:
 #      set predictor value
For example, -c lzw:2 to get LZW-encoded data with horizontal differencing

`ppm2tiff` Converter

With ppm2tiff we can convert PPM portable bixel map into TIFF. The usage is:

usage: ppm2tiff [options] input.ppm output.tif
where options are:
 -r #      make each strip have no more than # rows
 -R #      set x&y resolution (dpi)

 -c jpeg[:opts]  compress output with JPEG encoding
 -c lzw[:opts]   compress output with Lempel-Ziv & Welch encoding
 -c zip[:opts]   compress output with deflate encoding
 -c packbits   compress output with packbits encoding (the default)
 -c g3[:opts]  compress output with CCITT Group 3 encoding
 -c g4         compress output with CCITT Group 4 encoding
 -c none   use no compression algorithm on output

JPEG options:
 #      set compression quality level (0-100, default 75)
 r      output color image as RGB rather than YCbCr
LZW and deflate options:
 #      set predictor value
For example, -c lzw:2 to get LZW-encoded data with horizontal differencing

For other image formats, we can use for example convert to convert first the image into BMP, GIF or PPM. The command line tool convert is provided the ImageMagic open source software. Even if we don't have a graphical X11 Window System installed on the Linux server, we can get the convert command by installing the package imagemagick.

`raw2tiff` Converter

With the command raw2tiff we can convert RAW image data into TIFF. This can be use full if we compute the raster raw data witch must displaced as raster map. The usage is:

usage: raw2tiff [options] input.raw output.tif
where options are:
 -L      input data has LSB2MSB bit order (default)
 -M      input data has MSB2LSB bit order
 -r #      make each strip have no more than # rows
 -H #      size of input image file header in bytes (0 by default)
 -w #      width of input image in pixels
 -l #      length of input image in lines
 -b #      number of bands in input image (1 by default)

 -d data_type   type of samples in input image
where data_type may be:
 byte      8-bit unsigned integer (default)
 short      16-bit unsigned integer
 long      32-bit unsigned integer
 sbyte      8-bit signed integer
 sshort      16-bit signed integer
 slong      32-bit signed integer
 float      32-bit IEEE floating point
 double      64-bit IEEE floating point

 -p photo   photometric interpretation (color space) of the input image
where photo may be:
 miniswhite   white color represented with 0 value
 minisblack   black color represented with 0 value (default)
 rgb      image has RGB color model
 cmyk      image has CMYK (separated) color model
 ycbcr      image has YCbCr color model
 cielab      image has CIE L*a*b color model
 icclab      image has ICC L*a*b color model
 itulab      image has ITU L*a*b color model

 -s      swap bytes fetched from input file

 -i config   type of samples interleaving in input image
where config may be:
 pixel      pixel interleaved data (default)
 band      band interleaved data

 -c lzw[:opts]   compress output with Lempel-Ziv & Welch encoding
 -c zip[:opts]   compress output with deflate encoding
 -c jpeg[:opts]   compress output with JPEG encoding
 -c packbits   compress output with packbits encoding
 -c none   use no compression algorithm on output

JPEG options:
 #      set compression quality level (0-100, default 75)
 r      output color image as RGB rather than YCbCr
For example, -c jpeg:r:50 to get JPEG-encoded RGB data with 50% comp. quality

LZW and deflate options:
 #      set predictor value
For example, -c lzw:2 to get LZW-encoded data with horizontal differencing
 -o out.tif   write output to out.tif
 -h      this help message

Color Scale and Gray Scale

A RGB or Palette color TIFF image is converted to a greyscale image by combining percentages of the red, green, and blue channels. By default, output samples are created by taking 28% of the red channel, 59% of the green channel, and 11% of the blue channel:

grey = (28 * R + 59 * G + 11 * B ) / 100 = r * R + g * G + b * B

with r = 28%, g = 59% and b = 11%.

The greyscale is device independant, because we don't considere any Gamma Correction for the color model.

A map with greyscale [grey_0, garey_1] illustrates some scalar value range [V_0, V_1]. The greyscale should match linearly the scalar value, i.e.:

grey_x = grey_0 + x * (grey_1 - grey_0)

so that for x = 0 we get grey_0, and for x = 1 we get grey_1. Therefor we must have

grey_x = grey_0 + x * (grey_1 - grey_0)
            = r * R_0 + g * R_0 + b * B_0 + x * [ () - () ]

`tiff2bw` Color to Grayscale Converter

With the command tiff2bw we can convert a color TIFF to a gray scale TIFF. This is use full if we have some falls color raster map, from witch we wont to get the numerical value of a pixel, for example the elevation from a falls color hypsography. The usage is:

usage: tiff2bw [options] input.tif output.tif
where options are:
 -R %      use #% from red channel
 -G %      use #% from green channel
 -B %      use #% from blue channel

 -r #      make each strip have no more than # rows

 -c lzw[:opts]   compress output with Lempel-Ziv & Welch encoding
 -c zip[:opts]   compress output with deflate encoding
 -c packbits   compress output with packbits encoding
 -c g3[:opts]   compress output with CCITT Group 3 encoding
 -c g4      compress output with CCITT Group 4 encoding
 -c none   use no compression algorithm on output

LZW and deflate options:
 #      set predictor value
For example, -c lzw:2 to get LZW-encoded data with horizontal differencing

`tiffinfo` TIFF Tag Print

With the command tiffinfo we can print the TIFF tag values. The usage is:

usage: tiffinfo [options] input...
where options are:
 -D      read data
 -i      ignore read errors
 -c      display data for grey/color response curve or colormap
 -d      display raw/decoded image data
 -f lsb2msb   force lsb-to-msb FillOrder for input
 -f msb2lsb   force msb-to-lsb FillOrder for input
 -j      show JPEG tables
 -o offset   set initial directory offset
 -r      read/display raw image data instead of decoded data
 -s      display strip offsets and byte counts
 -w      display raw data in words rather than bytes
 -z      enable strip chopping
 -#      set initial directory (first directory is # 0)

`tiffdump` TIFF Tag Verbose Print

With the command tiffdump we can print a verbose version of TIFF tag values. The usage is:

usage: tiffdump [-h] [-o offset] [-m maxitems] file.tif ...

`tiffcmp` TIFF Tag Compare

With tiffcmp we can compare the TIFF tag structure a values from to TIFF files. The usage is:

usage: tiffcmp [options] file1 file2
where options are:
 -l      list each byte of image data that differs between the files
 -z #      list specified number of bytes that differs between the files
 -t      ignore any differences in directory tags