- -blend value
- blend the two images a given percent.
- -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 scene number by embedding
special format characters. Embed %f for filename,
%d for directory, %e for filename extention, %t for
top of filename, %m for magick, %w for width, %h for
height, %s for scene number, or \n for newline. 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.
- bumpmap
- The result of image shaded by image.
- replace
- 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 an 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, 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.
2 Restore to background color.
3 Restore to previous.
- -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 option is required for dithering to take
effect.
- -font name
- This option specifies the font to be used for
displaying normal 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).
- -geometry <width>{%}x<height>{%}{+-}<x offset>{+-
}<y offset>{!}{<}{>}
- the width and height of the image.
- 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.
- 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 direction
- direction image gravitates to within the composite. See X(1) for
details about the gravity specification.
- The image may not fill the composite completely (see
-geometry). 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. A gravity of
Forget stretches the composite to the same size as the image.
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 scene number in the label by
embedding special format characters. Embed %f for filename,
%d for directory, %e for filename extention, %t for
top of filename, %m for magick, %w for width, %h for
height, %s for scene number, or \n for newline. 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.
- -monochrome
- transform the image to black and white.
- -negate
- apply color inversion to image.
- 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:
Letter 612x 792
Tabloid 792x1224
Ledger 1224x 792
Legal 612x1008
Statement 396x 612
Executive 540x 720
A3 842x1190
A4 595x 842
A5 420x 595
B4 729x1032
B5 516x 729
Folio 612x 936
Quarto 610x 780
10x14 720x1008
- 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>. The default
is 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
(RFC 2083).
- -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).
- -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 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 option is required for this option to take
effect.
- -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.
Image manipulation software that works like magic.