Provided by: netpbm_11.07.00-2_amd64 
NAME
pamtotiff - convert a Netpbm image to a TIFF file
SYNOPSIS
pamtotiff
[-none | -packbits | -lzw | -g3 | -g4 | -flate | -adobeflate]
[-2d]
[-fill]
[-predictor=n]
[-msb2lsb|-lsb2msb]
[-rowsperstrip=n]
[-minisblack|-miniswhite|mb|mw]
[-truecolor]
[-color]
[-indexbits=bitwidthlist] [-xresolution=xres]
[-yresolution=yres] [-resolutionunit={inch | centimeter | none | in | cm | no}]
[-append]
[-tag=taglist]
[pamfile]
You can use the minimum unique abbreviation of the options. You can use two hyphens instead of one. You
can separate an option name from its value with white space instead of an equals sign.
DESCRIPTION
This program is part of Netpbm(1).
pamtotiff reads a PNM or PAM image as input and produces a TIFF file as output.
Actually, it handles multi-image Netpbm streams, producing multi-image TIFF streams (i.e. a TIFF stream
with multiple "directories"). But before Netpbm 10.27 (March 2005), it ignored all but the first Netpbm
image in the input stream.
The Output File
By default, the output goes to Standard Output. Alternatively, you can specify an output file with the
-output option and pamtotiff will write its output directly to that file.
Because of the way the TIFF library (which pamtotiff uses) works, when the program writes to Standard
Output, it generates the entire TIFF image in a temporary file and then copies it to Standard Output; you
may see negative performance effects of this.
The -output method avoids the performance effects of the copy through the temporary file, but there are
restrictions on the output file: it must be seekable and it must be readable. The program fails if it is
not. With Standard Output, neither of those restrictions applies.
With -output, if the file already exists and has data in it, pamtotiff appends the image to the existing
TIFF file. (A TIFF file may contain multiple images).
By default, pamtotiff creates the file named by -output if it does not already exist. But if you also
specify -append, the program fails if the file named by -output does not already exist.
Before Netpbm 10.67 (June 2014), there is no -output option and Standard Output must be seekable. So
pipes are out.
Before Netpbm 10.67 (June 2014), you could append to Standard Output. See below. The current program
does not have the ability; you must use -output to append to an existing TIFF file.
The difference above means current pamtotiff is actually not backward compatible, which is a rare thing
for Netpbm. But it's a good thing because the previous function was very strange and probably hardly
ever exploited.
Old Versions
As alluded to above, pamtotiff does output very differently in releases before 10.67. The following
describes the old function, which is unusual both for Netpbm and for Unix programs in general.
• The output file must be seekable. pamtotiff does not write it sequentially. Therefore, you can't
use a pipe; you can't pipe the output of pamtotiff to some other program. But any regular file
should work.
• If the output file descriptor is readable, you must either specify -append so as to add to the
existing file, or make sure the file is empty. Otherwise, pamtotiff will fail with an unhelpful
message telling you that a TIFF library function failed to open the TIFF output stream.
• If you are converting multiple images (your input stream contains multiple images), the output
file must be both readable and writable.
If you're using a Unix command shell to run pamtotiff, you use facilities of your shell to set up
Standard Output. In Bash, for example, you would set up a write-only Standard Output to the file
/tmp/myimage.tiff like this:
$ pamtotiff myimage.pnm >/tmp/myimage.tiff
In Bash, you would set up a read/write Standard Output to the file /tmp/myimage.tiff like this:
$ pamtotiff myimage.pnm 1<>/tmp/myimage.tiff
TIFF Capability
pamtotiff uses the Libtiff.org TIFF library (or whatever equivalent you provide) to generate the TIFF
output. Details of the format it produces are therefore controlled by that library.
OPTIONS
In addition to the options common to all programs based on libnetpbm (most notably -quiet, see
Common Options ⟨index.html#commonoptions⟩ ), pamtotiff recognizes the following command line options:
Compression
By default, pamtotiff creates a TIFF file with no compression. This is your best bet most of the time.
If you want to try another compression scheme or tweak some of the other even more obscure output
options, there are a number of options which to play.
Before Netpbm 8.4 (April 2000), the default was to use LZW compression. But then new releases of the
TIFF library started omitting the LZW compression capability because of concern about patents on LZW. So
since then, the default has been no compression. The LZW patents have now expired and new TIFF libraries
do LZW, but the pamtotiff behavior remains the same for compatibility with older TIFF libraries and
applications of pamtotiff.
The -none, -packbits, -lzw, -g3, -g4, -flate, and -adobeflate options are used to override the default
and set the compression scheme used in creating the output file.
The -predictor option is meaningful only with LZW compression: 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. By default, pamtotiff creates a TIFF file with msb-to-
lsb fill order. The -msb2lsb and -lsb2msb options are used to override the default and set the fill
order used in creating the file.
With some older TIFF libraries, -lzw doesn't work because the TIFF library doesn't do LZW compression.
This is because of concerns about Unisys's patent on LZW which was then in force. Actually, with very
old TIFF libraries, -lzw works because no distributors of the TIFF library were sensitive yet to the
patent issue.
-flate chooses "flate" compression, which is the patent-free compression common in the Unix world
implemented by the "Z" library. It is what the PNG format uses.
Fax Compression
If you have bilevel data (e.g. PBM), you can generate a TIFF that uses the same compression scheme
specified for use by fax machines. See the Fax Format(1) page for more information on these compression
schemes.
These formats all relate to ITU Group 3 and Group 4 fax machine standards.
The -g3 option chooses MH or MR compression: MR with the additional option -2d; MH without it. -g4
selects MMR. The option names are a little unfortunate and historical, but are consistent with the TIFF
specification.
MMR has a better compression ratio than the other two.
-fill specifies that for MH or MR compression, each encoded scanline shall be zero-filled to a byte
boundary.
-2d and -fill are meaningful only with -g3.
Fill Order
The -msb2lsb and lsb2msb options control the fill order.
The fill order is the order in which pixels are packed into a byte in the Tiff raster, in the case that
there are multiple pixels per byte. msb-to-lsb means that the leftmost columns go into the most
significant bits of the byte in the Tiff image. However, there is considerable confusion about the
meaning of fill order. Some believe it means whether 16 bit sample values in the Tiff image are little-
endian or big-endian. This is totally erroneous (The endianness of integers in a Tiff image is
designated by the image's magic number). However, ImageMagick and older Netpbm both have been known to
implement that interpretation. 2001.09.06.
If the image does not have sub-byte pixels, these options have no effect other than to set the value of
the FILLORDER tag in the Tiff image (which may be useful for those programs that misinterpret the tag
with reference to 16 bit samples).
Color Space
-color tells pamtotiff to produce a color, as opposed to grayscale, TIFF image if the input is PPM, even
if it contains only shades of gray. Without this option, pamtotiff produces a grayscale TIFF image if
the input is PPM and contains only shades of gray, and at most 256 shades. Otherwise, it produces a
color TIFF output. For PBM and PGM input, pamtotiff always produces grayscale TIFF output and this
option has no effect.
The -color option can prevent pamtotiff from making two passes through the input file, thus improving
speed and memory usage. See Multiple Passes ⟨#multipass⟩ .
-truecolor tells pamtotiff to produce the 24-bit RGB form of TIFF output if it is producing a color TIFF
image. Without this option, pamtotiff produces a colormapped (paletted) TIFF image unless there are more
than 256 colors (and in the latter case, issues a warning).
The -truecolor option can prevent pamtotiff from making two passes through the input file, thus improving
speed and memory usage. See Multiple Passes ⟨#multipass⟩ .
The -color and -truecolor options did not exist before Netpbm 9.21 (December 2001).
If pamtotiff produces a grayscale TIFF image, this option has no effect.
The -minisblack and -miniswhite options force the output image to have a "minimum is black" or "minimum
is white" photometric, respectively. If you don't specify either, pamtotiff uses minimum is black except
when using Group 3 or Group 4 compression, in which case pamtotiff follows CCITT fax standards and uses
"minimum is white." This usually results in better compression and is generally preferred for bilevel
coding. These photometrics are for grayscale images, so these options are invalid if the image is color
(but only if it is truly color; they are valid with, for example, a PPM image that contains only shades
of gray).
Before Netpbm 9.11 (February 200)1, pamtotiff always produced "minimum is black," because of a bug. In
either case, pamtotiff sets the photometric interpretation tag in the TIFF output according to which
photometric is actually used.
Before Netpbm 10.78 (March 2017), pamtotiff respected -miniswhite and -minisblack even with color images,
producing invalid TIFF images that have the indicated photometric but red, green, and blue raster planes.
The -indexbits option is meaningful only for a colormapped (paletted) image. In this kind of image, the
raster contains values which are indexes into a table of colors, with the indexes normally taking less
space that the color description in the table. pamtotiff can generate indexes of 1, 2, 4, or 8 bits. By
default, it will use 8, because many programs that interpret TIFF images can't handle any other width.
But if you have a small number of colors, you can make your image considerably smaller by allowing fewer
than 8 bits per index, using the -indexbits option. The value is a comma-separated list of the bit
widths you allow. pamtotiff chooses the smallest width you allow that allows it to index the entire
color table. If you don't allow any such width, pamtotiff fails. Normally, the only useful value for
this option is 1,2,4,8, because a program either understands the 8 bit width (default) or understands
them all.
In a Baseline TIFF image, according to the 1992 TIFF 6.0 specification, 4 and 8 are the only valid
widths. There are no formal standards that allow any other values.
This option was added in June 2002. Before that, only 8 bit indices were possible.
Extra Tags
There are lots of tag types in the TIFF format that don't correspond to any information in the PNM format
or to anything in the conversion process. For example, a TIFF_ARTIST tag names the artist who created
the image.
You can tell pamtotiff explicitly to include tags such as this in its output with the -tag option. You
identify a list of tag types and values and pamtotiff includes a tag in the output for each item in your
list.
The value of -tag is the list of tags, like this example:
-tag=subfiletype=reducedimage,documentname=Fred,xposition=25
As you see, it is a list of tag specifications separated by commas. Each tag specification is a name and
a value separated by an equal sign. The name is the name of the tag type, except in arbitrary
upper/lower case. One place to see the names of TIFF tag types is in the TIFF library's tiff.h file,
where there is a macro defined for each consisting of "TIFF_" plus the name. E.g. for the SUBFILETYPE
tag type, there is a macro TIFF_SUBFILETYPE.
The format of the value specification for a tag (stuff after the equal sign) depends upon what kind of
value the tag type has:
• Integer: a decimal number
• Floating point number: a decimal number
• String: a string
• Enumerated (For example, a 'subfiletype' tag takes an enumerated value. Its possible values are
REDUCEDIMAGE, PAGE, and MASK.): The name of the value. You can see the possible value names in
the TIFF library's tiff.h file, where there is a macro defined for each consisting of a qualifier
plus the value name. E.g. for the REDUCEDIMAGE value of a SUBFILETYPE tag, you see the macro
FILETYPE_REDUCEDIMAGE.
The TIFF format assigns a unique number to each enumerated value and you can specify that number,
in decimal, as an alternative. This is useful if you are using an extension of TIFF that
pamtotiff doesn't know about.
If you specify a tag type with -tag that is not independent of the content of your PNM source image and
pamtotiff's conversion process (i.e. a tag type in which pamtotiff is interested), pamtotiff fails. For
example, you cannot specify an IMAGEWIDTH tag with -tag, because pamtotiff generates an IMAGEWIDTH tag
that gives the actual width of the image.
-tag was new in Netpbm 10.31 (December 2005).
Output
See The Output File ⟨#output⟩ .
-output names the output file. Without this option pamtotiff writes to Standard Output.
The -append option tells pamtotiff only to append to the file named by output; not create it. Without
this option, the program creates the file it does not already exist. But even then, if the file does
already exist, the program appends the image to what is in the file already. (A TIFF file may contain
multiple images).
-append has no effect if you don't also specify -output.
Before Netpbm 10.67 (June 2014), -append means something rather different: it means to append the image
to the output TIFF file (which is always Standard Output in 10.67) instead of replacing its contents.
-append was new in Netpbm 10.27 (March 2005).
Other
You can use the -rowsperstrip option to set the number of rows (scanlines) in each strip of data in the
output file. By default, the output file has the number of rows per strip set to a value that will
ensure each strip is no more than 8 kilobytes long.
NOTES
There are myriad variations of the TIFF format, and this program generates only a few of them. pamtotiff
creates a grayscale TIFF file if its input is a PBM (monochrome) or PGM (grayscale) or equivalent PAM
file. pamtotiff also creates a grayscale file if it input is PPM (color) or equivalent PAM, but there is
only one color in the image.
If the input is a PPM (color) file and there are 256 colors or fewer, but more than 1, pamtotiff
generates a color palette TIFF file. If there are more colors than that, pamtotiff generates an RGB (not
RGBA) single plane TIFF file. Use pnmtotiffcmyk to generate the cyan-magenta-yellow-black ink color
separation TIFF format.
The number of bits per sample in the TIFF output is determined by the maxval of the Netpbm input. If the
maxval is less than 256, the bits per sample in the output is the smallest number that can encode the
maxval. If the maxval is greater than or equal to 256, there are 16 bits per sample in the output.
Extra Channels
Like most Netpbm programs, pamtotiff's function is mostly undefined if the input is PAM image with tuple
type other than BLACKANDWHITE, GRAYSCALE, or RGB. Most of the statements in this manual assume the input
is not such an exotic PAM. But there is a little defined processing of other PAM subformats.
pamtotiff assumes any 1 plane PAM image is BLACKANDWHITE or GRAYSCALE (and doesn't distinguish between
those two).
pamtotiff assumes a PAM with more than 1 plane is of tuple type RGB except with that number of planes
instead of 3. pamtotiff doesn't really understand red, green, and blue, so it has no trouble with a
2-component or 5-component color space. The TIFF format allows an arbitrary number of color components,
so pamtotiff simply maps the PAM planes directly to TIFF color components. I don't know if the meanings
of 5 components in a TIFF image are standard at all, but the function is there if you want to use it.
Note that pamtotiff may generate either a truecolor or colormapped image with an arbitrary number of
color components. In the truecolor case, the raster has that number of planes. In the colormapped case,
the raster has of course 1 plane, but the color map has all the color components in it.
The most common reason for a PAM to have extra planes is when the tuple type is xxx_ALPHA, which means
the highest numbered plane is a transparency plane (alpha channel). At least one user found that a TIFF
with an extra plane for transparency was useful.
Note that the grayscale detection works on N-component colors, so if your planes aren't really color
components, you'll want to disable this via the -color option.
Multiple Passes
pamtotiff reads the input image once if it can, and otherwise twice. It needs that second pass (which
happens before the main pass, of course) to analyze the colors in the image and generate a color map
(palette) and determine if the image is grayscale. So the second pass happens only when the input is
PPM. And you can avoid it then by specifying both the -truecolor and -color options.
If the input image is small enough to fit in your system's file cache, the second pass is very fast. If
not, it requires reading from disk twice, which can be slow.
When the input is from a file that cannot be rewound and reread, pamtotiff reads the entire input image
into a temporary file which can, and works from that. Even if it needs only one pass.
Before Netpbm 9.21 (December 2001), pamtotiff always read the entire image into virtual memory and then
did one, two, or three passes through the memory copy. The -truecolor and -color options did not exist.
The passes through memory would involve page faults if the entire image did not fit into real memory.
The image in memory required considerably more memory (12 bytes per pixel) than the cached file version
of the image would.
Resolution
A Tiff image may contain information about the resolution of the image, which means how big in real
dimensions (centimeters, etc.) each pixel in the raster is. That information is in the TIFF XRESOLUTION,
YRESOLUTION, and RESOLUTIONUNIT tags. By default, pamtotiff does not include any tags of these types,
but you can specify them with the -tags option.
There are also options -xresolution, -yresolution, and -resolutionunit, but those are obsolete. Before
-tags existed (before Netpbm 10.31 (December 2005), they were the only way.
Note that the number of pixels in the image and how much information each contains is determined
independently from the setting of the resolution tags. The number of pixels in the output is the same as
in the input, and each pixel contains the same information. For your resolution tags to be meaningful,
they have to consistent with whatever created the PNM input. E.g. if a scanner turned a 10 centimeter
wide image into a 1000 pixel wide PNM image, then your horizontal resolution is 100 pixels per
centimeter, and if your XRESOLUTION tag says anything else, something that prints your TIFF image won't
print the proper 10 centimeter image.
The value of the XRESOLUTION tag is a floating point decimal number that tells how many pixels there are
per unit of distance in the horizontal direction. -yresolution is analogous for the vertical direction.
The unit of distance is given by the value of the RESOLUTIONUNIT option. That value is either INCH,
CENTIMETER, or NONE. NONE means the unit is arbitrary or unspecified. This could mean that the creator
and user of the image have a separate agreement as to what the unit is. But usually, it just means that
the horizontal and vertical resolution values cannot be used for anything except to determine aspect
ratio (because even though the unit is arbitrary or unspecified, it has to be the same for both
resolution numbers).
If you don't use a -tag option to specify the resolution tag and use the obsolete options instead, note
the following:
• If you don't include an specify -xresolution, the Tiff image does not contain horizontal
resolution information. Likewise for -yresolution. If you don't specify -resolutionunit, the
default is inches.
• Before Netpbm 10.16 (June 2003), -resolutionunit did not exist and the resolution unit was always
inches.
HISTORY
pamtotiff was originally pnmtotiff and did not handle PAM input. It was extended and renamed in Netpbm
10.30 (October 2005).
SEE ALSO
tifftopnm(1), pnmtotiffcmyk(1), pamdepth(1), pamtopnm(1), pam(1)
AUTHOR
Derived by Jef Poskanzer from ras2tiff.c, which is Copyright (c) 1990 by Sun Microsystems, Inc. Author:
Patrick J. Naughton (naughton@wind.sun.com).
DOCUMENT SOURCE
This manual page was generated by the Netpbm tool 'makeman' from HTML source. The master documentation
is at
http://netpbm.sourceforge.net/doc/pamtotiff.html