mogrify (1)
transform an image or sequence of images
SYNOPSIS
mogrify
[ [ options ...] file ...]
DESCRIPTION
mogrify transforms an image or a sequence of images. These
transforms include image scaling, image rotation, color reduction, and
others. The transmogrified image overwrites the original image.
EXAMPLES
To convert all the TIFF files in a particular directory to JPEG, use:
mogrify -format jpeg *.tiff
To scale an image of a cockatoo to exactly 640 pixels in width and 480
pixels in height, use:
mogrify -geometry 640x480! cockatoo.miff
OPTIONS
-antialias
-blur \fIfactor\fP
blur an image. Specify factor as the percent enhancement
(0.0 - 99.9%).
-border \fI<width>x<height>\fP
surround the image with a border of color. See X(1) for details
about the geometry specification.
-bordercolor \fIcolor\fP
-box \fIcolor\fP
set the color of the annotation bounding box. See -draw or
for further details.
See X(1) for details about the color specification.
-charcoal \fIfactor\fP
simulate a charcoal drawing.
-colorize \fIvalue\fP
colorize the image with the pen color.
Specify the amount of colorization as a percentage. You can apply separate
colorization values to the red, green, and blue channels of the image with a
colorization value list delineated with slashes (e.g. 0/0/50).
-colors \fIvalue\fP
preferred number of colors in the image.
The actual number of colors in the image may be less than your request,
but never more. Note, this is a color reduction option. Images with
less unique colors than specified with this option will have any duplicate
or unused colors removed.
Refer to quantize(9) for more details.
If more than one image is specified on the command line, a single
colormap is created and saved with each image.
Note, options -colormap, -dither, -colorspace, and
-treedepth affect the color reduction algorithm.
-colorspace \fIvalue\fP
the type of colorspace: GRAY, OHTA, RGB,
Transparent, XYZ, YCbCr, YIQ, YPbPr,
YUV, or CMYK.
Color reduction, by default, takes place in the RGB color space.
Empirical evidence suggests that distances in color spaces such as YUV
or YIQ correspond to perceptual color differences more closely
than do distances in RGB space. These color spaces may give better
results when color reducing an image. Refer to quantize(9) for
more details.
The Transparent color space behaves uniquely in that it preserves
the matte channel of the image if it exists.
The -colors or -monochrome option is required
for this option to take effect.
-comment \fIstring\fP
annotate an image with a comment.
By default, each image is commented with its file name. Use this
option to assign a specific comment to the image. Optionally you can
include the image filename, type, width, height, or other image
attributes by embedding special format characters:
%b file size
%d directory
%e filename extension
%f filename
%h height
%m magick
%p page number
%s scene number
%t top of filename
%w width
%x x resolution
%y y resolution
\\n newline
\\r carriage return
For example,
-comment "%m:%f %wx%h"
produces an image comment of MIFF:bird.miff 512x480 for an image
titled bird.miff and whose width is 512 and height is 480.
If the first character of string is @, the image comment is read
from a file titled by the remaining characters in the string.
-compress \fItype\fP
the type of image compression: None, BZip, Fax, Group4,
JPEG, LZW, RunlengthEncoded, or Zip.
Specify \+compress to store the binary image in an uncompressed format.
The default is the compression type of the specified image file.
-contrast
enhance or reduce the image contrast.
This option enhances the intensity differences between the
lighter and darker elements of the image. Use -contrast to
enhance the image or +contrast to reduce the image contrast.
-crop \fI<width>x<height>{\+-}<x offset>{\+-}<y offset>{%}\fP
preferred size and location of the cropped image. See X(1) for details
about the geometry specification.
To specify a percentage width or height instead, append %. For example
to crop the image by ten percent on all sides of the image, use -crop 10%.
Use cropping to apply image processing options, or transmogrify, only a
particular area of an image.
Omit the x and y offset to generate one or more subimages of a uniform size.
Use cropping to crop a particular area of an image. Use -crop
0x0 to trim edges that are the background color. Add an x and y offset
to leave a portion of the trimmed edges with the image.
-cycle \fIamount\fP
displace image colormap by amount.
Amount defines the number of positions each colormap entry is shifted.
-delay \fI<1/100ths of a second>\fP
display the next image after pausing.
This option is useful for regulating the animation of a sequence of
GIF images within Netscape. 1/100ths of a second must expire
before the redisplay of the image sequence. The default is no delay
between each showing of the image sequence. The maximum delay is 65535.
-density \fI<width>x<height>\fP
vertical and horizontal resolution in pixels of the image.
This option specifies an image density when decoding a Postscript or
Portable Document page. The default is 72 pixels per inch in the horizontal
and vertical direction. This option is used in concert with -page.
-depth \fIvalue\fP
depth of the image. This is the number of bits in a pixel. The only
acceptable values are 8 or 16.
-despeckle
reduce the speckles within an image.
-display \fIhost:display[.screen]\fP
specifies the X server to contact; see X(1).
-dispose \fImethod\fP
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.
-dither
apply Floyd/Steinberg error diffusion to the image.
The basic strategy of dithering is to trade intensity resolution for
spatial resolution by averaging the intensities of several neighboring
pixels. Images which suffer from severe contouring when reducing colors
can be improved with this option.
The -colors or -monochrome option is required for this option
to take effect.
Use +dither to render Postscript without text or graphic aliasing.
-draw \fIstring\fP
annotate an image with one or more graphic primitives.
Use this option to annotate an image with one or more graphic primitives.
The primitives include
point
line
rectangle
fillRectangle
circle
fillCircle
ellipse
fillEllipse
polygon
fillPolygon
color
matte
text
image
Point, line, color, matte, text, and
image each require a single coordinate. Line requires a
start and end coordinate, while rectangle expects an upper left
and lower right coordinate. Circle has a center coordinate and a
coordinate on the outer edge. Use Ellipse to draw a partial ellipse
centered at the given point, specified width and height, and start and
end of arc in degrees (e.g. 100,100 100,150 0,360). Finally, polygon
requires three or more coordinates defining its boundaries. Coordinates are
integers separated by an optional comma. For example, to define a circle
centered at 100,100 that extends to 150,150 use:
-draw 'circle 100,100 150,150'
Use color to change the color of a pixel. Follow the
pixel coordinate with a method:
point
replace
floodfill
filltoborder
reset
Consider the target pixel as that specified by your coordinate. The
point method recolors the target pixel. The replace method
recolors any pixel that matches the color of the target pixel.
Floodfill recolors any pixel that matches the color of the target
pixel and is a neighbor, whereas filltoborder recolors any neighbor
pixel that is not the border color. Finally, reset recolors all pixels.
Use matte to the change the pixel matte value to transparent.
Follow the pixel coordinate with a method (see the color
primitive for a description of methods). The point method
changes the matte value of the target pixel. The replace method
changes the matte value of any pixel that matches the color of the
target pixel. Floodfill changes the matte value of any pixel
that matches the color of the target pixel and is a neighbor, whereas
filltoborder changes the matte value of any neighbor pixel that is not the
border color (-bordercolor). Finally reset changes the matte value
of all pixels.
Use text to annotate an image with text. Follow the text
coordinates with a string. If the string has embedded spaces, enclose
it in double quotes. Optionally you can
include the image filename, type, width, height, or other image
attributes by embedding special format characters. See -comment
for details.
For example,
-draw 'text 100,100 "%m:%f %wx%h"'
annotates the image with MIFF:bird.miff 512x480 for an image
titled bird.miff and whose width is 512 and height is 480.
To generate a Unicode character (TrueType fonts only), embed the
code as an escaped hex string (e.g. \\0x30a3).
Use image to composite an image with another image. Follow the
image coordinates with the filename of an image.
If the first character of string is @, the text is read
from a file titled by the remaining characters in the string.
You can set the primitive color, font color, and font bounding box color with
-pen, -font, and -box respectively. Options are
processed in command line order so be sure to use -pen
before the -draw option.
-edge \fIfactor\fP
detect edges with an image. Specify factor as the percent enhancement
(0.0 - 99.9%).
-emboss
-enhance
apply a digital filter to enhance a noisy image.
-equalize
perform histogram equalization to the image.
-filter \fIvalue\fP
use this type of filter when resizing an image.
Use this option to affect the resizing operation of an image (see
-geometry). Choose from these filters:
Point
Box
Triangle
Hermite
Hanning
Hamming
Blackman
Gaussian
Quadratic
Cubic
Catrom
Mitchell
Lanczos
Bessel
Sinc
The default filter is Lanczos.
-flip
create a "mirror image" by reflecting the image scanlines in the vertical
direction.
-flop
create a "mirror image" by reflecting the image scanlines in the horizontal
direction.
-format \fItype\fP
This option will convert any image to the image format you specify.
See convert(1) for a list of image format types supported by
ImageMagick.
By default the file is written to its original name. However, if the
filename extension matches a supported format, the extension is replaced
with the image format type specified with -format. For example,
if you specify tiff as the format type and the input image
filename is image.gif, the output image filename becomes
image.tiff.
-font \fIname\fP
use this font when annotating the image with text.
If the font is a fully qualified X server font name, the font is obtained
from an X server (e.g. -*-helvetica-medium-r-*-*-12-*-*-*-*-*-iso8859-*). To
use a TrueType font, precede the TrueType filename with a @ (e.g.
@times.ttf). Otherwise, specify a Postscript font (e.g. helvetica).
-frame \fI<width>x<height>+<outer bevel width>+<inner bevel width>\fP
surround the image with an ornamental border. See X(1) for details
about the geometry specification.
The color of the border is specified with the -mattecolor command line
option.
-fuzz \fIdistance\fP
colors within this distance are considered equal.
A number of algorithms search for a target color. By default the color
must be exact. Use this option to match colors that are close to the
target color in RGB space. For example, if you want to automatically trim the
edges of an image with -crop 0x0 but the image was scanned. The
target background color may differ by a small amount. This option can
account for these differences.
-gamma \fIvalue\fP
level of gamma correction.
The same color image displayed on two different workstations may look
different due to differences in the display monitor. Use gamma
correction to adjust for this color difference. Reasonable values
extend from 0.8 to 2.3.
You can apply separate gamma values to the red, green, and blue
channels of the image with a gamma value list delineated with slashes
(i.e. 1.7/2.3/1.2).
Use +gamma to set the image gamma level without actually adjusting
the image pixels. This option is useful if the image is of a known
gamma but not set as an image attribute (e.g. PNG images).
-geometry \fI<width>x<height>{\+-}<x offset>{\+-}<y offset>{%}{!}{<}{>}\fP
preferred width and height of the image. See X(1) for details
about the geometry specification.
By default, the width and height are maximum values. That is, the
image is expanded or contracted to fit the width and height value while
maintaining the aspect ratio of the image. Append an exclamation point
to the geometry to force the image size to exactly the size you
specify. For example, if you specify 640x480! the image width is
set to 640 pixels and height to 480. If only one factor is
specified, both the width and height assume the value.
To specify a percentage width or height instead, append %. The
image size is multiplied by the width and height percentages to obtain
the final image dimensions. To increase the size of an image, use a
value greater than 100 (e.g. 125%). To decrease an image's size, use a
percentage less than 100.
Use > to change the dimensions of the image only
if its size exceeds the geometry specification. < resizes
the image only if its dimensions is less than the geometry
specification. For example, if you specify 640x480> and the
image size is 512x512, the image size does not change. However, if
the image is 1024x1024, it is resized to 640x480.
-gravity \fItype\fP
direction text gravitates to when annotating the image: NorthWest, North,
NorthEast, West, Center, East, SouthWest, South, SouthEast.
See X(1) for details about the gravity specification.
The direction you choose specifies where to
position the text when annotating the image. For example Center gravity
forces the text to be centered within the image.
By default, the text gravity is NorthWest.
-implode \fIfactor\fP
implode image pixels about the center. Specify factor as the percent
implosion (0 - 99.9 %) or explosion (-99.9 - 0)
-interlace \fItype\fP
the type of interlacing scheme: None, Line, Plane, or
Partition. The default is None.
This option is used to specify the type of interlacing scheme for raw
image formats such as RGB or YUV. No means do not
interlace (RGBRGBRGBRGBRGBRGB...), Line uses scanline
interlacing (RRR...GGG...BBB...RRR...GGG...BBB...), and Plane uses
plane interlacing (RRRRRR...GGGGGG...BBBBBB...). Partition is like
plane except the different planes are saved to individual files (e.g.
image.R, image.G, and image.B).
Use Line, or Plane to create an interlaced GIF or progressive
JPEG image.
-label \fIname\fP
assign a label to an image.
Use this option to assign a specific label to the image. Optionally
you can include the image filename, type, width, height, or scene
number in the label by embedding special format characters. Optionally you can
include the image filename, type, width, height, or other image
attributes by embedding special format characters. See -comment
for details.
For example,
-label "%m:%f %wx%h"
produces an image label of MIFF:bird.miff 512x480 for an image
titled bird.miff and whose width is 512 and height is 480.
If the first character of string is @, the image label is read
from a file titled by the remaining characters in the string.
When converting to Postscript, use this option to specify a header string
to print above the image. Specify the label font with -font.
-layer \fItype\fP
the type of layer: Red, Green, Blue, or
Matte.
Use this option to extract a particular layer from the image.
Matte, for example, is useful for extracting the opacity values
from an image.
-linewidth \fIvalue\fP
set the width of a line. See -draw for further details.
-loop \fIiterations\fP
add Netscape loop extension to your GIF animation.
A value other than zero forces the animation to repeat itself up to
iterations times.
-map \fIfilename\fP
choose a particular set of colors from this image.
By default, color reduction chooses an optimal set of colors that
best represent the original image. Alternatively, you can choose a
particular set of colors from an image file with this option. Use
+map to reduce all images in an image sequence to a single
optimal set of colors that best represent all the images.
-matte
store matte channel if the image has one otherwise create an opaque one.
-modulate \fIvalue\fP
vary the brightness, saturation, and hue of an image.
Specify the percent change in brightness, the color saturation, and the hue
separated by commas. For example, to increase the color brightness
by 20% and decrease the color saturation by 10% and leave the hue
unchanged, use: -modulate 20,-10.
-monochrome
transform the image to black and white.
-negate
replace every pixel with its complementary color (white becomes black, yellow
becomes blue, etc.).
The red, green, and blue intensities of an image are negated. Use
+negate to only negate the grayscale pixels of the image.
-noise
add or reduce noise in an image.
The principal function of noise peak elimination filter is to smooth
the objects within an image without losing edge information and without
creating undesired structures. The central idea of the algorithm is to
replace a pixel with its next neighbor in value within a 3 x 3 window,
if this pixel has been found to be noise. A pixel is defined as noise
if and only if this pixel is a maximum or minimum within the 3 x 3 window.
PP
Use +noise followed by a noise type to add noise to an image. Choose
from these noise types:
Uniform
Gaussian
Multiplicative
Impulse
Laplacian
Poisson
-normalize
transform image to span the full range of color values.
This is a contrast enhancement technique.
-opaque \fIcolor\fP
change this color to the pen color within the image. See -pen for
more details.
-page \fI<width>x<height>{\+-}<x offset>{\+-}<y offset>{%}{!}{<}{>}\fP
preferred size and location of an image canvas.
Use this option to specify the dimensions of the Postscript page in
dots per inch or a TEXT page in pixels. The choices for a Postscript page are:
11x17 792 1224
Ledger 1224 792
Legal 612 1008
Letter 612 792
LetterSmall 612 792
ArchE 2592 3456
ArchD 1728 2592
ArchC 1296 1728
ArchB 864 1296
ArchA 648 864
A0 2380 3368
A1 1684 2380
A2 1190 1684
A3 842 1190
A4 595 842
A4Small 595 842
A5 421 595
A6 297 421
A7 210 297
A8 148 210
A9 105 148
A10 74 105
B0 2836 4008
B1 2004 2836
B2 1418 2004
B3 1002 1418
B4 709 1002
B5 501 709
C0 2600 3677
C1 1837 2600
C2 1298 1837
C3 918 1298
C4 649 918
C5 459 649
C6 323 459
Flsa 612 936
Flse 612 936
HalfLetter 396 612
For convenience you can specify the page size by media (e.g.
A4, Ledger, etc.). Otherwise, -page behaves much like -geometry
(e.g. -page letter+43+43>).
To position a GIF image, use -page {\+-}<x offset>{\+-}<y offset>
(e.g. -page +100+200).
For a Postscript page, the image is sized as in -geometry and
positioned relative to the lower left hand corner of the page by
{\+-}<x offset>{\+-}<y offset>. Use -page 612x792>, for example,
to center the image within the page. If the image size exceeds the
Postscript page, it is reduced to fit the page.
The default page dimensions for a TEXT image is 612x792.
This option is used in concert with -density.
-paint \fIradius\fP
simulate an oil painting.
Each pixel is replaced by the most frequent color in a circular neighborhood
whose width is specified with radius.
-pen \fIcolor\fP
set the color of the font or opaque color. See -draw for further details.
See X(1) for details about the color specification. A pen can also
be an image. Specify the pen color as an image name preceded by a @
(e.g. @tile.gif).
-pointsize \fIvalue\fP
pointsize of the Postscript font.
-quality \fIvalue\fP
JPEG/MIFF/PNG compression level.
For the JPEG image format, quality is 0 (worst) to 100 (best). The default
quality is 75.
Quality for the MIFF and PNG image format sets the amount of image compression
(quality / 10) and filter-type (quality % 10). Compression quality
values range from 0 (worst) to 100 (best). If filter-type is 4
or less, the specified filter-type is used for all scanlines:
0: none
1: sub
2: up
3: average
4: Paeth
If filter-type is 5, adaptive filtering is used when quality
is greater than 50 and the image does not have a color map,
otherwise no filtering is used.
If filter-type is 6 or more, adaptive filtering with
minimum-sum-of-absolute-values is used.
The default is quality is 75. Which means nearly the best compression
with adaptive filtering.
For further information, see the PNG specification (RFC 2083),
<http://www.w3.org/pub/WWW/TR>.
-raise \fI<width>x<height>\fP
lighten or darken image edges to create a 3-D effect. See X(1) for
details about the geometry specification.
Use -raise to create a raised effect, otherwise use +raise.
-region \fI<width>x<height>{\+-}<x offset>{\+-}<y offset>\fP
apply options to a portion of the image.
By default, any command line options are applied to the entire image. Use
-region to restrict operations to a particular area of the image.
-roll \fI{\+-}<x offset>{\+-}<y offset>\fP
roll an image vertically or horizontally. See X(1) for details
about the geometry specification.
A negative x offset rolls the image left-to-right. A negative
y offset rolls the image top-to-bottom.
-rotate \fIdegrees{<}{>}\fP
apply Paeth image rotation to the image.
Use > to rotate the image only if its width exceeds the
height. < rotates the image only if its width is less than
the height. For example, if you specify -90> and the image size
is 480x640, the image is not rotated by the specified angle. However,
if the image is 640x480, it is rotated by -90 degrees.
Empty triangles left over from rotating the image are filled with
the color defined as bordercolor (class borderColor).
-sample \fIgeometry\fP
scale image with pixel sampling.
-scene \fIvalue\fP
-seed \fIvalue\fP
pseudo-random number generator seed value.
-segment \fI<cluster threshold>x<smoothing threshold>\fP
segment an image by analyzing the histograms of the color components and
identifying units that are homogeneous with the fuzzy c-means technique.
Specify cluster threshold as the number of pixels in each cluster must
exceed the the cluster threshold to be considered valid. Smoothing
threshold eliminates noise in the second derivative of the
histogram. As the value is increased, you can expect a smoother second
derivative. The default is 1.5. See IMAGE SEGMENTATION for
details.
-shade \fI<azimuth>x<elevation>\fP
shade the image using a distant light source.
Specify azimuth and elevation as the position of the light source.
Use +shade to return the shading results as a grayscale image.
-sharpen \fIfactor\fP
sharpen an image. Specify factor as the percent
enhancement (0.0 - 99.9%).
-shear \fI<x degrees>x<y degrees>\fP
shear the image along the X or Y axis by a positive or negative shear angle.
Shearing slides one edge of an image along the X or Y axis, creating a
parallelogram. An X direction shear slides an edge along the X axis,
while a Y direction shear slides an edge along the Y axis. The amount
of the shear is controlled by a shear angle. For X direction shears,
x degrees> is measured relative to the Y axis, and similarly, for
Y direction shears y degrees is measured relative to the X axis.
Empty triangles left over from shearing the image are filled with
the color defined as bordercolor (class borderColor).
See X(1) for details.
-size \fI<width>x<height>+<offset>\fP
width and height of the image.
Use this option to specify the width and height of raw images whose
dimensions are unknown such as GRAY, RGB, or CMYK.
In addition to width and height, use -size to skip any header
information in the image or tell the number of colors in a MAP
image file, (e.g. -size 640x512+256).
For Photo CD images, choose from these sizes:
192x128
384x256
768x512
1536x1024
3072x2048
Finally, use this option to choose a particular resolution layer of a JBIG
or JPEG image (e.g. -size 1024x768).
-solarize \fIthreshold\fP
negate all pixels above the threshold level. Specify factor as the
percent threshold of the intensity (0 - 99.9%).
This option produces a solarization effect seen when exposing
a photographic film to light during the development process.
-spread \fIamount\fP
displace image pixels by a random amount.
Amount defines the size of the neighborhood around each pixel to
choose a candidate pixel to swap.
-swirl \fIdegrees\fP
swirl image pixels about the center.
Degrees defines the tightness of the swirl.
-texture \fIfilename\fP
name of texture to tile onto the image background.
-threshold \fIvalue\fP
Create a bi-level image such that any pixel intensity that
is equal or exceeds the threshold is reassigned the maximum intensity otherwise
the minimum intensity.
-transparency \fIcolor\fP
make this color transparent within the image.
-treedepth \fIvalue\fP
Normally, this integer value is zero or one. A zero or one tells
mogrify to choose a optimal tree depth for the color reduction
algorithm.
An optimal depth generally allows the best representation of the source
image with the fastest computational speed and the least amount of
memory. However, the default depth is inappropriate for some images.
To assure the best representation, try values between 2 and 8 for this
parameter. Refer to quantize(9) for more details.
The -colors or -monochrome option is required for this option
to take effect.
-units \fItype\fP
the type of image resolution: Undefined, PixelsPerInch, or
PixelsPerCentimeter. The default is Undefined.
-verbose
print detailed information about the image.
This information is printed: image scene number; image name; image
size; the image class (DirectClass or PseudoClass); the total
number of unique colors (if known); and the number of seconds to read and
transform the image. Refer to miff(5) for a description of
the image class.
If -colors is also specified, the total unique colors in the image
and color reduction error values are printed. Refer to quantize(9)
for a description of these values.
-view \fIstring\fP
FlashPix viewing parameters.
-wave \fI<amplitude>x<wavelength>\fP
alter an image along a sine wave.
Specify amplitude and wavelength to effect the characteristics of
the wave.
Options are processed in command line order.
Any option you specify on the command line remains in effect until it is
explicitly changed by specifying the option again with a different effect.
For example, to mogrify two images, the first with 32 colors and the
second with only 16 colors, use:
mogrify -colors 32 cockatoo.miff -colors 16 macaw.miff
By default, the image format is determined by its magic number. To
specify a particular image format, precede the filename with an image
format name and a colon (i.e. ps:image) or specify the image type as
the filename suffix (i.e. image.ps). See convert(1) for a list
of valid image formats.
Specify file as - for standard input and output. If
file has the extension .Z or .gz, the file is
uncompressed with uncompress or gunzip respectively and
subsequently compressed using with compress or gzip.
Finally, precede the image file name with | to pipe to or from a
system command.
Use an optional index enclosed in brackets after a file name to specify
a desired subimage of a multi-resolution image format like Photo CD
(e.g. img0001.pcd[4]) or a range for MPEG images (e.g. video.mpg[50-75]).
A subimage specification can be disjoint (e.g. image.tiff[2,7,4]).
For raw images, specify a subimage with a geometry (e.g. -size 640x512
image.rgb[320x256+50+50]).
Prepend an at sign (@) to a filename to read a list of image
filenames from that file. This is convenient in the event you have too
many image filenames to fit on the command line.
IMAGE SEGMENTATION
Use -segment to segment an image by analyzing the histograms of the color
components and identifying units that are homogeneous with the fuzzy c-means
technique. The scale-space filter analyzes the histograms of the three
color components of the image and identifies a set of classes. The
extents of each class is used to coarsely segment the image with
thresholding. The color associated with each class is determined by
the mean color of all pixels within the extents of a particular class.
Finally, any unclassified pixels are assigned to the closest class with
the fuzzy c-means technique.
The fuzzy c-Means algorithm can be summarized as follows:
o Build a histogram, one for each color component of the image.
o For each histogram, successively apply the scale-space filter and
build an interval tree of zero crossings in the second derivative at
each scale. Analyze this scale-space ``fingerprint'' to determine
which peaks or valleys in the histogram are most predominant.
o The fingerprint defines intervals on the axis of the histogram. Each
interval contains either a minima or a maxima in the original signal.
If each color component lies within the maxima interval, that pixel is
considered ``classified'' and is assigned an unique class number.
o Any pixel that fails to be classified in the above thresholding pass is
classified using the fuzzy c-Means technique. It is assigned to one
of the classes discovered in the histogram analysis phase.
The fuzzy c-Means technique attempts to cluster a pixel by finding the local
minima of the generalized within group sum of squared error objective
function. A pixel is assigned to the closest class of which the fuzzy
membership has a maximum value.
For additional information see
Young Won Lim, Sang Uk Lee, "On The Color Image Segmentation Algorithm Based
on the Thresholding and the Fuzzy c-Means Techniques", Pattern Recognition,
Volume 23, Number 9, pages 935-952, 1990.
SEE ALSO
COPYRIGHT
1998 1998 E. I. du Pont de Nemours and Company
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files ("ImageMagick"),
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Except as contained in this notice, the name of the E. I. du Pont de
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ACKNOWLEDGEMENTS
Michael Halle, Spatial Imaging Group at MIT, for the initial
implementation of Alan Paeth's image rotation algorithm.
David Pensak, E. I. du Pont de Nemours and Company, for providing a
computing environment that made this program possible.
Paul Raveling, USC Information Sciences Institute, for the original
idea of using space subdivision for the color reduction algorithm.
AUTHORS
John Cristy, E.I. du Pont de Nemours and Company Incorporated
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