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MIFF(5) FILE FORMATS MIFF(5)
NAME
MIFF - ImageMagick's file format for raster images.
SYNOPSIS
#include <image.h>
DESCRIPTION
A MIFF image file consist of two sections. The first
section is composed of keywords describing the image in text
form. The next section is the binary image data. The two
sections are separated by a : character immediately followed
by a newline. Generally, the first section has a form-feed
and newline proceeding the : character. You can then list
the image keywords with more, without printing the binary
image that follows the : separator.
Each keyword must be separated by at least one space but can
be separated with control characters such a form-feed or
newline.
A list of valid keywords follows:
class=DirectClass | PseudoClass
identifies the type of binary image stored within the
file.
This keyword is optional. If it is not specified, a
DirectClass image format is assumed. An explanation of
DirectClass and PseudoClass image data follows this
list.
colors=value
specifies the number of colors in the image, and for
pseudo-color images the size of the colormap.
This keyword is optional. However, if a colormap size
is not specified, a linear colormap is assumed for
pseudo-color images.
columns=value
is a required keyword and specifies the number of
columns, or width in pixels, of the image.
compression=QEncoded | RunlengthEncoded
identifies how the image stored within the file is
compressed.
This keyword is optional. If it is not specified, the
image is assumed to be uncompressed. A detailed
explanation of runlength-encoded and predictive
arithmetic image compression follows this list.
id=ImageMagick
is a required keyword and identifies this file as a
MIFF image.
packets=value
specifies the number of compressed color packets in the
image data section.
This keyword is optional, but recommended, for
runlength-encoded image compression. It is required
for arithimetic encoded image compression. A detailed
explanation of image compression follows this list.
rows=value
is a required keyword and specifies the number of rows,
or height in pixels, of the image.
scene=value
is an optional keyword and is a reference number for
sequencing of images.
This keyword is typically useful for animating a
sequence of images.
signature=value
is an optional keyword and is a character string that
uniquely identifies the image colormap.
A unique identifier for the colormap is useful for
animating a sequence of PseudoClass images. The
default identifier is a digital signature computed from
RSA's Data Security MD4 Digest Algorithm described in
RFC 1186, October 1990. The colormap signature is
generally computed if scene has a value other than
zero.
Comments can be included in the keyword section. Comments
must begin with a { character and end with a } character.
An example keyword section follows:
{
Rendered via Dore by Sandy Hause.
}
id=ImageMagick
class=PseudoClass colors=256
compression=RunlengthEncoded packets=27601
columns=1280 rows=1024
scene=1 signature=d79e1c308aa5bbcdeea8ed63df412da9
^L
:
The binary image data that follows the keyword text is
stored in one of two binary classes as specified by the
class keyword: DirectClass or PseudoClass.
Use the DirectClass class to store continuous-tone images.
DirectClass requires that the image pixels immediately
follow the keyword text and be stored as binary red, green,
and blue intensity values. The total number of pixels
expected is equal to the number of pixel columns times the
number of pixel rows as specified by the columns and rows
keywords.
If the compression keyword is not specified, a red, green,
and blue byte in that order is expected for each pixel of
the image.
If compression is QEncoded, each red, green, and blue byte
intensity value is encoded using the predictive arithmetic
compression algorithm. Use the packets keyword to specify
the total number of arithimetic encoded packets that
comprise the image. Refer to "JPEG-9-R6 Working Draft for
Development of JPEG CD", January 1991, for implementation
specific details.
If compression is RunlengthEncoded, each red, green, and
blue byte intensity value is followed by a count byte. This
value specifies the number of horizonally contiguous pixels
in the image of that color. The count (0-255) is one less
than the actual number of contiguous pixels; thus a single
packet can represent from 1 up to 256 identical pixels. The
total number of pixels specified by the individual count
bytes must add up to the number of pixel columns times the
number of pixel rows as specified by the columns and rows
keywords. Use packets to specify the total number of
runlength-encoded packets that comprise the image.
Use the PseudoClass class to store pseudo-color images.
PseudoClass requires that the image colormap and pseudo-
color pixels immediately follow the keyword text. The
colormap is stored as contiguous red, green, and blue
intensity values. The number of intensity values expected
is determined by the colors keyword. Note, an image
colormap is restricted to at most 65535 entries. The binary
pseudo-color image is stored as indexes into the colormap.
If the colormap size exceeds 256 entries, then each colormap
index is two bytes each with the most-significant-byte
first. The total number of pixels expected is equal to the
number of pixel columns times the number of pixel rows as
specified by the columns and rows keywords.
If the compression keyword is not specified, a colormap
index is expected for each pixel of the image.
If compression is QEncoded, each colormap index is encoded
using the predictive arithmetic compression algorithm. Use
the packets keyword to specify the total number of
arithimetic encoded packets comprise the image. Refer to
"JPEG-9-R6 Working Draft for Development of JPEG CD",
January 1991, for implementation specific details.
If compression is RunlengthEncoded, each colormap index is
followed by a count byte. This value specifies the number
of horizonally contiguous pixels in the image of that color.
The count (0-255) is one less than the actual number of
contiguous pixels; thus a single packet can represent from 1
up to 256 identical pixels. The total number of pixels
specified by the individual count bytes must add up to the
number of pixels expected in the image as specified by the
columns and rows keywords. Use packets to specify the total
number of runlength-encoded packets that comprise the image.
SEE ALSO
display(1), animate(1), import(1), montage(1), mogrify(1),
more(1), compress(1)
COPYRIGHT
Copyright 1992 E. I. du Pont de Nemours & Company
Permission to use, copy, modify, distribute, and sell this
software and its documentation for any purpose is hereby
granted without fee, provided that the above copyright
notice appear in all copies and that both that copyright
notice and this permission notice appear in supporting
documentation, and that the name of E. I. du Pont de Nemours
& Company not be used in advertising or publicity pertaining
to distribution of the software without specific, written
prior permission. E. I. du Pont de Nemours & Company makes
no representations about the suitability of this software
for any purpose. It is provided "as is" without express or
implied warranty.
E. I. du Pont de Nemours & Company disclaims all warranties
with regard to this software, including all implied
warranties of merchantability and fitness, in no event shall
E. I. du Pont de Nemours & Company be liable for any
special, indirect or consequential damages or any damages
whatsoever resulting from loss of use, data or profits,
whether in an action of contract, negligence or other
tortious action, arising out of or in connection with the
use or performance of this software.
AUTHORS
John Cristy, E.I. du Pont de Nemours & Company Incorporated
ImageMagick Last change: 1 July 1991 4
