MIFF(5)
NAME
MIFF - Magick Image File Format is a platform-independent
format for storing bitmap images. MIFF is a part of the
ImageMagick toolkit of image manipulation utilities for
the X Window System. ImageMagick is capable of converting
many different image file formats to and from MIFF (e.g.
JPEG, XPM, TIFF, etc.).
SYNOPSIS
#include <<image.h>>
DESCRIPTION
A MIFF image file consist of two sections. The first sec-
tion is a header composed of keywords describing the image
in text form. The next section is the binary image data.
The header is separated from the image data by a : charac-
ter immediately followed by a newline.
The MIFF header is composed entirely of LATIN-1 charac-
ters. The fields in the header are keyword and value com-
bination in the keyword=value format, with each keyword
and value separated by an equal sign (=). Each key-
word=value combination is delimited by at least one con-
trol or whitespace character. Comments may appear in the
header section and are always delimited by braces. The
MIFF header always ends with a colon (:) character, fol-
lowed by a newline character. It is also common for a
formfeed and a newline character to appear before the
colon. You can then list the image keywords with more(1),
without printing the binary image that follows the colon
separator.
The following is a list of keyword=value combinations that
may be found in a MIFF file:
class=DirectClass
class=PseudoClass the type of binary image data
stored in the MIFF file. If this keyword is not
present, DirectClass image data is assumed.
colors=value
the number of colors in a DirectClass image. For a
PseudoClass image, this keyword specifies the size
of the colormap. If this keyword is not present in
the header, and the image is PseudoClass, a linear
256 color grayscale colormap is used with the image
data.
columns=value
the width of the image in pixels. This is a
required keyword and has no default.
compression=RunlengthEncoded
compression=Zip the type of algorithm used to
compress the image data. If this keyword is not
present, the image data is assumed to be uncom-
pressed.
delay <1/100ths of a second>
the interframe delay in an image sequence. The
maximum delay is 65535.
depth=8
depth=16 the depth of a single color value repre-
senting values from 0 to 255 (depth 8) or 65535
(depth 16). If this keyword is absent, a depth of
8 is assumed.
gamma=value
the gamma of the image. If it is not specified, a
gamma of 1.0 (linear brightness response) is
assumed,
id=ImageMagick
identifies the file as a MIFF-format image file.
This keyword is required and has no default.
Although this keyword can appear anywhere in the
header, it should start as the first keyword of the
header in column 1. This will allow programs like
file(1) to easily identify the file as MIFF.
label= value""
defines a short title or caption for the image. If
any whitespace appears in the label, it must be
enclosed within double quotes.
matte=True
matte=False specifies whether a DirectClass image
has matte data. Matte data is generally useful for
image compositing. This keyword has no meaning for
pseudo-color images.
montage=<width>x<height>{+-}<x offset>{+-}<y offset>
size and location of the individual tiles of a com-
posite image. See X(1) for details about the geom-
etry specification.
Use this keyword when the image is a composite of a
number of different tiles. A tile consists of an
image and optionally a border and a label. <width>
is the size in pixels of each individual tile in
the horizontal direction and <height> is the size
in the vertical direction. Each tile must have an
equal number of pixels in width and equal in
height. However, the width can differ from the
height. <x offset> is the offset in number of pix-
els from the vertical edge of the composite image
where the first tile of a row begins and <y offset>
is the offset from the horizontal edge where the
first tile of a column begins.
If this keyword is specified, a directory of tile
names must follow the image header. The format of
the directory is explained below.
packets=value
the number of compressed color packets in the image
data section. This keyword is optional for Run-
lengthEncoded images, mandatory for Zip images, and
not used for uncompressed image.
page= value""
preferred size and location of an image canvas.
rows=value
the height of the image in pixels. This is a
required keyword and has no default.
scene=value
the sequence number for this MIFF image file. This
optional keyword is used when a MIFF image file is
one in a sequence of files used in an animation.
signature=value
this optional keyword contains a string that
uniquely identifies the image pixel contents.
RSA's Data Security MD5 Digest Algorithm is recom-
mended.
The following is a sample MIFF header. In this
example, <FF> is a formfeed character:
id=ImageMagick
class=PseudoClass colors=256 signa-
ture=d79e1c308aa5bbcdeea8ed63df412da9
compression=RunlengthEncoded packets=27601
columns=1280 rows=1024
scene=1
{
Rendered via Dore by Sandi Tennyson.
}
<FF>
:
Note that keyword=value combinations may be separated by
newlines or spaces and may occur in any order within the
header. Comments (within braces) may appear anywhere
before the colon.
If you specify the montage keyword in the header, follow
the header with a directory of image tiles. This direc-
tory consists of a name for each tile of the composite
image separated by a newline character. The list is ter-
minated with a NULL character.
Following the header (or image directory if the montage
keyword is in the header) is the binary image data itself.
How the image data is formatted depends upon the class of
the image as specified (or not specified) by the value of
the class keyword in the header.
DirectClass images (class=DirectClass) are continuous-
tone, RGB images stored as intensity values in red-green-
blue order. Each color value is one byte in size for an
image depth of 8 and there are three bytes per pixel (four
with an optional matte value). If the depth is 16, each
color value is two bytes with the most significant byte
being first. The total number of pixels in a DirectClass
image is calculates by multiplying the rows value by the
column value in the header.
PseudoClass images (class=PseudoClass) are colormapped RGB
images. The colormap is stored as a series of red-green-
blue pixel values, each value being a byte in size. If
the image depth is 16, each colormap entry is two bytes
with the most significant byte being first. The number of
colormap entries is indicated by the colors keyword in the
header, with a maximum of 65,535 total entries allowed.
The colormap data occurs immediately following the header
(or image directory if the montage keyword is in the
header).
PseudoClass image data is an array of index values into
the color map. If there are 256 or fewer colors in the
image, each byte of image data contains an index value.
If the image contains more than 256 colors or the depth is
16, the index value is stored as two contiguous bytes with
the most significant byte being first. The total number
of pixels in a PseudoClass image is calculated by multi-
plying the rows value by the columns value in the header.
The image data in a MIFF file may be uncompressed or may
be compressed using one of two algorithms. The compres-
sion keyword in the header indicates how the image data is
compressed. The run-length encoding (RLE) algorithm may be
used to encode image data into packets of compressed data.
For DirectClass images, runs of identical pixels values
(not BYTE values) are encoded into a series of four-byte
packets (five bytes if a matte value is included). The
first three bytes of the packet contain the red, green,
and blue values of the pixel in the run. The fourth byte
contains the number of pixels in the run. This value is
in the range of 0 to 255 and is one less than the actual
number of pixels in the run. For example, a value of 127
indicates that there are 128 pixels in the run.
For PseudoClass images, the same RLE algorithm is used.
Runs of identical index values are encoded into packets.
Each packet contains the colormap index value followed by
the number of index values in the run. The number of
bytes in a PseudoClass RLE packet will be either two or
three, depending upon the size of the index values. The
number of RLE packets stored in the file is specified by
the packets keyword in the header, but is not required.
Use Zip compression to achieve a greater compression ratio
than run-length encoding. The number of compressed pack-
ets stored in the file is specified by the packets keyword
in the header.
MIFF files may contain more than one image. Simply con-
catenate each individual image (composed of a header and
image data) into one file.
SEE ALSO
display(1) animate(1) import(1) montage(1) mogrify(1)
convert(1) more(1) compress(1)
COPYRIGHT
Copyright 1998 E. I. du Pont de Nemours and Company
Permission is hereby granted, free of charge, to any per-
son obtaining a copy of this software and associated docu-
mentation files ("ImageMagick"), to deal in ImageMagick
without restriction, including without limitation the
rights to use, copy, modify, merge, publish, distribute,
sublicense, and/or sell copies of ImageMagick, and to per-
mit persons to whom the ImageMagick is furnished to do so,
subject to the following conditions:
The above copyright notice and this permission notice
shall be included in all copies or substantial portions of
ImageMagick.
The software is provided "as is", without warranty of any
kind, express or implied, including but not limited to the
warranties of merchantability, fitness for a particular
purpose and noninfringement. In no event shall E. I. du
Pont de Nemours and Company be liable for any claim, dam-
ages or other liability, whether in an action of contract,
tort or otherwise, arising from, out of or in connection
with ImageMagick or the use or other dealings in ImageMag-
ick.
Except as contained in this notice, the name of the E. I.
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AUTHORS
John Cristy, E.I. du Pont de Nemours and Company Incorpo-
rated