 -colors
value |
-
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.
-
Note, options -dither, -colorspace, and -treedepth
affect the color reduction algorithm.
| -colorspace
value |
-
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
string |
-
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 attribute by embedding
special format characters:
%b file size
%d directory
%e filename extention
%f filename
%h height
%i input filename
%l label
%m magick
%n number of scenes
%o output filename
%p page number
%q quantum depth
%s scene number
%t top of filename
%u unique temporary 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.
| -compose
operator |
-
the type of image composition.
-
By default, each of the composite image pixels are replaced by the corresponding
image tile pixel. You can choose an alternate composite operation. How
each operator behaves is described below.
| over |
-
The result will be the union of the two image shapes, with
composite
image obscuring image in the region of overlap.
| in |
-
The result is simply composite image cut by the shape of
image.
None of the image data of image will be in the result.
| out |
-
The resulting image is composite image with the shape of
image
cut out.
| atop |
-
The result is the same shape as image image, with
composite image
obscuring image where the image shapes overlap. Note this differs
from over because the portion of
composite image outside
image's
shape does not appear in the result.
| xor |
-
The result is the image data from both composite image and
image
that is outside the overlap region. The overlap region will be blank.
| plus |
-
The result is just the sum of the image data. Output values are cropped
to 255 (no overflow). This operation is independent of the matte channels.
| minus |
-
The result of composite image - image, with underflow cropped
to zero. The matte channel is ignored (set to 255, full coverage).
| add |
-
The result of composite image + image, with overflow wrapping
around (mod 256).
| subtract |
-
The result of composite image - image, with underflow wrapping
around (mod 256). The add and subtract operators can
be used to perform reversible transformations.
| difference |
-
The result of abs(composite image - image). This is useful
for comparing two very similar images.
| multiply |
-
The result of composite image * image. This is useful
for the creation of drop-shadows.
| bumpmap |
-
The result of image shaded by image.
| copy |
-
The resulting image is image replaced with
composite image.
Here the matte information is ignored.
-
The image compositor requires a matte, or alpha channel in the image for
some operations. This extra channel usually defines a mask which represents
a sort of a cookie-cutter for the image. This is the case when matte is
255 (full coverage) for pixels inside the shape, zero outside, and between
zero and 255 on the boundary. For certain operations, if image does
not have a matte channel, it is initialized with 0 for any pixel matching
in color to pixel location (0,0), otherwise 255 (to work properly
borderwidth
must be 0).
| -compress
type |
-
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.
| -density
<width>x<height> |
-
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
| -displace<horizontal
scale>x<vertical scale> |
-
shift image pixels as defined by a displacement map.
-
With this option, composite image is used as a displacement map.
Black, within the displacement map, is a maximum positive displacement.
White is a maximum negative displacement and middle gray is neutral. The
displacement is scaled to determine the pixel shift. By default, the displacement
applies in both the horizontal and vertical directions. However, if you
specify
mask, composite image is the horizontal X displacement
and
mask the vertical Y displacement.
| -display
host:display[.screen] |
-
specifies the X server to contact; see X(1).
| -dispose
method |
-
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.
| -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.
| -font
name |
-
This option specifies the font to be used for displaying normal text.
-
You can tag a font to specify whether it is a Postscript, Truetype, or X11
font. For example, Arial.ttf is a Truetype font, ps:helvetica
is Postscript, and x:fixed is X11.
| -geometry
{+-}<x offset>{+-}<y offset>{%}{!}{<}{>}
|
-
location of the composite image.
-
By default the images are combined relative to the image gravity (see
-gravity). Use <x offset> and <y
offset> to specify a particular location to combine the images.
| -gravity
type |
-
direction image gravitates to within the composite: 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 image within the
composite. For example Center gravity forces the image to be centered
within the composite. By default, the image gravity is NorthWest.
| -interlace
type |
-
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. None 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
name |
-
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 other image attribute
by embedding special format character. 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.
| -matte |
-
store matte channel if the image has one otherwise create an opaque one.
| -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.
| -page
<width>x<height>{+-}<x
offset>{+-}<y offset>{%}{!}{<}{>} |
-
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 "+1"00+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 {+-}<xoffset>{+-}<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.
| -quality
value |
-
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.
| -scene
value |
-
image scene number.
| -size
<width>{%}x<height>{%}{+offset}{!} |
-
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).
| -stegano |
-
hide watermark within an image.
-
Use an offset to start the image hiding some number of pixels from the
beginning of the image. Note this offset and the image size. You will need
this information to recover the steganographic image (e.g. display
-size 320x256+35 stegano:image.png).
| -stereo |
-
combine two image to create a stereo anaglyph.
-
The left side of the stereo pair is saved as the red channel of the output
image. The right sife is saved as the green channel. Red-blue stereo glasses
are required to properly view the stereo image.
| -tile |
-
repeat composite operation across image.
| -treedepth
value |
-
Normally, this integer value is zero or one. A zero or one tells combine
to choose an 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 option is required for this option to take effect.
| -type
type |
-
the image type:
Bilevel, Grayscale, Palette,
PaletteMatte, TrueColor, TrueColorMatte,
or ColorSeparation.
| -verbose |
-
print detailed information about the image.
-
This information is printed: image scene number; image name; combined image
name; image size; the image class (DirectClass or PseudoClass);
the total number of unique colors; and the number of seconds to read and
combine the image.
Contents
Image
manipulation software that works like magic.