NAME¶
MIFF - Magick Image File Format
SYNOPSIS¶
#include <image.h>
DESCRIPTION¶
The Magick Image File Format (MIFF) 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.).
A MIFF image file consist of two sections. The first section is a header
composed of keys describing the image in text form. The next section is the
binary image data. The header is separated from the image data by a
:
character immediately followed by a
newline.
The MIFF header is composed entirely of LATIN-1 characters. The fields in the
header are key and value combination in the
key=value format, with each
key and value separated by an equal sign (=). Each
key=value
combination is delimited by at least one control 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, followed by a
ctrl-Z character. It is also common to proceed the colon with a
formfeed and a
newline character. The
formfeed prevents
the listing of binary data when using
more(1) under Unix where the
ctrl-Z has the same effect with the
type command on the Win32
command line.
The following is a list of
key=value combinations that may be found in a
MIFF file:
- background-color=color
- border-color=color matte-color=color these
optional keys reflects the image background, border, and matte colors
respectively. A color can be a name (e.g. white) or a hex value (e.g.
#ccc).
- class=DirectClass
- class=PseudoClass the type of binary image data stored in
the MIFF file. If this key is not present, DirectClass image data
is assumed.
- colors=value
- the number of colors in a DirectClass image. For a
PseudoClass image, this key specifies the size of the colormap. If
this key is not present in the header, and the image is
PseudoClass, a linear 256 color grayscale colormap is used with the
image data. The maximum number of colormap entries is 65535.
colorspace= CMYK the colorspace of the pixel data. The
default is RGB.
- columns=value
- the width of the image in pixels. This is a required key and has no
default.
- compression=BZip
- compression=Fax compression=JPEG
compression= LZW compression=RLE
compression= Zip the type of algorithm used to compress the
image data. If this key is not present, the image data is assumed to be
uncompressed.
- 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 representing
values from 0 to 255 (depth 8) or 65535 (depth 16). If this key is absent,
a depth of 8 is assumed.
- dispose value
- GIF disposal method.
Here are the valid methods:
0 No disposal specified.
1 Do not dispose between frames.
2 Overwrite frame with background color from header.
3 Overwrite with previous frame.
- 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 key is required and
has no default. Although this key can appear anywhere in the header, it
should start as the first key of the header in column 1. This will allow
programs like file(1) to easily identify the file as MIFF.
- iterations value
- the number of times an image sequence loops before stopping.
- label={value}
- defines a short title or caption for the image. If any whitespace appears
in the label, it must be enclosed within braces.
- matte=True
- matte=False specifies whether a DirectClass image has
matte data. Matte data is generally useful for image compositing. This key
has no meaning for pseudo-color images.
- montage=<width>x<height>{+-}<x offset>{+-}<y
offset>
- size and location of the individual tiles of a composite image. See
X(1) for details about the geometry specification.
Use this key 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 pixels 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 key is specified, a directory of tile names must follow the image
header. The format of the directory is explained below.
- page=value
- preferred size and location of an image canvas.
- profile-icc=value
- the number of bytes in the International Color Consortium color profile.
The profile is defined by the ICC profile specification located at
ftp://sgigate.sgi.com/pub/icc/icc34.ps.
- colorspace=RGB
- red-primary=x,y
- green-primary=x,y blue-primary=x,y
white-point= x,y this optional key reflects the chromaticity
primaries and white point.
- rendering-intent=saturation
- rendering-intent=perceptual
rendering-intent=absolute
rendering-intent=relative Rendering intent is the CSS-1
property that has been defined by the International Color Consortium
(http://www.color.org).
- resolution=<x-resolution>x<y-resolution>
- vertical and horizontal resolution of the image. See units for the
specific resolution units (e.g. pixels per inch).
- rows=value
- the height of the image in pixels. This is a required key and has no
default.
- scene=value
- the sequence number for this MIFF image file. This optional key is used
when a MIFF image file is one in a sequence of files used in an
animation.
- signature=value
- this optional key contains a string that uniquely identifies the image
pixel contents. NIST's SHA-256 message digest algorithm is
recommended.
- units=pixels-per-inch
- units=pixels-per-centimeter image resolution units.
Other key value pairs are permitted. If a value contains whitespace it must
be enclosed with braces as illustrated here:
id=ImageMagick
class=PseudoClass colors=256
compression=RunlengthEncoded packets=27601
columns=1280 rows=1024
signature=d79e1c308aa5bbcdeea8ed63df412da9
copyright={Copyright (c) 2001 ImageMagick Studio}
<FF>
:
Note that
key=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 key in the header, follow the header with a
directory of image tiles. This directory consists of a name for each tile of
the composite image separated by a
newline character. The list is
terminated with a NULL character.
If you specify the
color-profile key in the header, follow the header (or
montage directory if the
montage key is in the header) with the binary
color profile.
Next comes 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 key in the header.
DirectClass images (class=DirectClass) are continuous-tone, images stored as RGB
(red, green, blue), RGBA (red, green, blue, alpha), or CMYK (cyan, yellow,
magenta, black) intensity values as defined by the colorspace key. Each
intensity value is one byte in length for images of depth 8 (0..255), whereas,
images of depth 16 (0..65535) require two bytes in most significant byte first
order.
PseudoClass images (class=PseudoClass) are colormapped RGB images. The colormap
is stored as a series of red, green, and blue pixel values, each value being a
byte in size. If the image depth is 16, each colormap entry consumes two bytes
with the most significant byte being first. The number of colormap entries is
defined by the colors key. The colormap data occurs immediately following the
header (or image directory if the montage key 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 image depth is 16, the index
value is stored as two contiguous bytes with the most significant byte being
first. If matte is true, each colormap index is followed by a 1 or 2-byte
alpha value.
The image data in a MIFF file may be uncompressed, runlength encoded, Zip
compressed, or BZip compressed. The compression key in the header defines how
the image data is compressed. Uncompressed pixels are just stored one scanline
at a time in row order. Runlength encoded compression counts runs of identical
adjacent pixels and stores the pixels followed by a length byte (the number of
identical pixels minus 1). Zip and BZip compression compresses each row of an
image and preceeds the compressed row with the length of compressed pixel
bytes as a word in most significant byte first order.
MIFF files may contain more than one image. Simply concatenate 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 (C) 2000 ImageMagick Studio, a non-profit organization dedicated to
making software imaging solutions freely available.
Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation 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 permit 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 ImageMagick Studio be liable for any claim, damages 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
ImageMagick.
Except as contained in this notice, the name of the ImageMagick Studio shall not
be used in advertising or otherwise to promote the sale, use or other dealings
in ImageMagick without prior written authorization from the ImageMagick
Studio.
AUTHORS¶
John Cristy, ImageMagick Studio