MIFF - Magick Image File Format
#include <image.h>
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.
display(1),
animate(1),
import(1),
montage(1),
mogrify(1),
convert(1),
more(1),
compress(1)
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