CONVERT(1) CONVERT(1)
NAME
convert - converts an input file using one image format to
an output file with a differing image format.
SYNOPSIS
convert [ options ... ] inputfile outputfile
DESCRIPTION
Convert converts an input file using one image format to
an output file with a differing image format. 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). Specify file as - for standard input or out-
put. If file has the extension .Z, the file is decoded
with uncompress.
Convert recognizes the following image formats:
Tag Description
-------------------------------------------------------------
ALPHA Raw alpha bytes.
AVS Advanced Visualization System image file format.
CMYK Raw cyan, magenta, yellow, and black bytes.
EPS Encapsulated PostScript file
FAX Group 3.
GIF Graphic Image Format.
GRAY Raw gray bytes.
HISTOGRAM
JPEG
MIFF Machine Independant file format.
MTV
PNM Portable bitmap.
PS PostScript file.
RGB Raw red, green, and blue bytes.
RLE Utah Raster Toolkit; read only.
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SUN SUN raster.
TEXT raw text file; read only.
TIFF Tagged Image File Format.
VICAR read only.
VIFF
X select image from X server screen; read only.
XC constant image of X server border color.
XBM X11 bitmap.
XWD X11 window dump.
YUV Raw Y, U, and V bytes. U and V, normally -0.5
through 0.5, are normalized to the range 0 through
255 to fit within a byte.
EXAMPLES
To convert a MIFF image of a cockatoo to a SUN raster
image, use:
convert cockatoo.miff sun:cockatoo.ras
To convert a MTV image of a molecule to a JPEG image, use:
convert molecule.mtv molecule.jpeg
To convert a raw GRAY image to a portable graymap, use:
convert -geometry 768x512 gray:raw image.pnm
OPTIONS
-alpha
store alpha channel if the image has one.
-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 col-
ors than specified with this option will remain
unchanged. Refer to Quantize(9) for more details.
Note, options -dither, -colorspace, and -treedepth
affect the color reduction algorithm.
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-colorspace value
the type of colorspace: GRAY, RGB, XYZ, YCbCr, YIQ,
or YUV.
Color reduction, by default, takes place in the RGB
color space. Empirical evidence suggests that dis-
tances 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 -colors or -monochrome option is required for
this option to take effect.
-compress type
the type of image compression: QEncoded or Runlength-
Encoded.
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 horizonal density of the image.
This option specifies an image density whose inter-
pretation changes with the type of image. The
default is 72 dots per inch in the horizonal and ver-
tical direction for Postscript. Text files default
to 80 characters in width and 60 lines in height.
Use this option to alter the default density.
-display host:display[.screen]
specifies the X server to contact; see X(1).
-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 dis-
playing normal text. The default is fixed.
-geometry <width>x<height>
the width and height of the image.
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Use this option to specified the width and height of
raw images whose dimensions are unknown such as GRAY,
RGB, and CMYK. This option can also change the
default 8.5 by 11 width and height of the Postscript
canvas.
-interlace type
the type of interlacing scheme: NONE, LINE, or PLANE.
This option is used to specify the type of interlac-
ing 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...).
-monochrome
transform the image to black and white.
Monochrome images can benefit from error diffusion.
Use -dither with this option to diffuse the error.
-quality value
JPEG quality setting.
Quality is 0 (worst) to 100 (best). The default is
75.
-scene value
image scene number.
-treedepth value
Normally, this integer value is zero or one. A zero
or one tells Display to choose a optimal tree depth
for the color reduction algorithm.
An optimal depth generally allows the best represen-
tation of the source image with the fastest computa-
tional speed and the least amount of memory. How-
ever, the default depth is inappropriate for some
images. To assure the best representation, try val-
ues 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; converted image name; image size; the
image class (DirectClass or PseudoClass); the total
number of unique colors; and the number of seconds
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to read and convert the image.
Change '-' to '+' in any option above to reverse its
effect. For example, specify +alpha to store the image
without its alpha channel.
To specify a particular image format prefix file with the
image type and a colon (i.e. ps:image) or specify the
image type as the filename suffix (i.e. image.ps). See
the beginning of this document for a list of valid image
formats. If file has the extension .Z, the file size is
reduced using Lempel-Ziv coding with compress. If file
already exists, you will be prompted as to whether it
should be overwritten.
When you specify X as your image type, the filename has
special meaning. It specifies an X window by id, name, or
root. If no filename is specified, the window is selected
by clicking the mouse in the desired window.
ENVIRONMENT
DISPLAY
To get the default host, display number, and screen.
SEE ALSO
display(1), animate(1), mogrify(1), Quantize(9), X(1),
MIFF(5)
COPYRIGHT
Copyright 1992 E. I. du Pont de Nemours & Company
Permission to use, copy, modify, distribute, and sell this
software and its documentation for any purpose is hereby
granted without fee, provided that the above copyright
notice appear in all copies and that both that copyright
notice and this permission notice appear in supporting
documentation, and that the name of E. I. du Pont de
Nemours & Company not be used in advertising or publicity
pertaining to distribution of the software without spe-
cific, written prior permission. E. I. du Pont de Nemours
& Company makes no representations about the suitability
of this software for any purpose. It is provided "as is"
without express or implied warranty.
E. I. du Pont de Nemours & Company disclaims all war-
ranties with regard to this software, including all
implied warranties of merchantability and fitness, in no
event shall E. I. du Pont de Nemours & Company be liable
for any special, indirect or consequential damages or any
damages whatsoever resulting from loss of use, data or
profits, whether in an action of contract, negligence or
other tortious action, arising out of or in connection
with the use or performance of this software.
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AUTHORS
John Cristy, E.I. du Pont De Nemours & Company Incorpo-
rated
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