Manual: pamtotiff
Pamtotiff User Manual(1) General Commands Manual Pamtotiff User Manual(1)
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 sepa‐
rate 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 op‐
tion 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 gen‐
erates the entire TIFF image in a temporary file and then copies it to Standard Output; you may see negative perfor‐
mance 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 Out‐
put, 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 -ap‐
pend, 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. De‐
tails 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 ),
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 be‐
cause 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 endi‐
anness 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 sam‐
ples).
Color Space
-color tells pamtotiff to produce a color, as opposed to grayscale, TIFF image if the input is PPM, even if it con‐
tains 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 mem‐
ory usage. See Multiple Passes .
-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 .
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 con‐
tains values which are indexes into a table of colors, with the indexes normally taking less space that the color de‐
scription 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 under‐
stands 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 any‐
thing 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 con‐
sisting 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 RE‐
DUCEDIMAGE 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 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 compo‐
nents. 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 re‐
quires 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 tempo‐
rary 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 consider‐
ably 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 (cen‐
timeters, etc.) each pixel in the raster is. That information is in the TIFF XRESOLUTION, YRESOLUTION, and RESOLU‐
TIONUNIT 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 cre‐
ated 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 un‐
specified, 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 follow‐
ing:
• If you don't include an specify -xresolution, the Tiff image does not contain horizontal resolution informa‐
tion. 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 (Octo‐
ber 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
netpbm documentation 05 April 2017 Pamtotiff User Manual(1)