convert
NAME
convert - converts an input file using one image format to
an output file with a differing image format.
SYNOPSIS
convert [ options ... ] input_file output_file
DESCRIPTION
convert converts an input file using one image format to an
output file with a differing image format.
convert recognizes the following image formats:
Tag Description
-------------------------------------------------------------------------------
AVS AVS X image file.
BMP Microsoft Windows bitmap image file.
CMYK Raw cyan, magenta, yellow, and black bytes.
EPS Adobe Encapsulated PostScript file.
EPSF Adobe Encapsulated PostScript file.
EPSI Adobe Encapsulated PostScript Interchange format.
FAX Group 3.
FITS Flexible Image Transport System.
GIF Compuserve Graphics image file.
GIF87 Compuserve Graphics image file (version 87a).
GRAY Raw gray bytes.
HDF Hierarchical Data Format.
HISTOGRAM
JPEG Joint Photographic Experts Group file interchange for-
mat.
MAP Red, green, and blue colormap bytes followed by the
image colormap indexes.
MATTE Raw matte bytes.
MIFF Magick image file format.
MTV
NULL NULL image.
PCD Photo CD.
PCX ZSoft IBM PC Paintbrush file.
PDF Portable Document Format.
PICT Apple Macintosh QuickDraw/PICT file.
PNG Portable Network Graphics.
PNM Portable bitmap.
PS Adobe PostScript file.
PS2 Adobe Level II PostScript file.
RAD Radiance image format.
RGB Raw red, green, and blue bytes.
RGBA Raw red, green, blue and matte bytes.
RLE Utah Run length encoded image file; read only.
SGI Irix RGB image file.
SUN SUN Rasterfile.
TEXT raw text file; read only.
TGA Truevision Targa image file.
TIFF Tagged Image File Format.
TILE tile image with a texture.
VICAR read only.
VID Visual Image Directory.
VIFF Khoros Visualization image file.
X select image from X server screen.
XC constant image of X server color. Specify the desired
color as the filename.
XBM X11 bitmap file.
XPM X11 pixmap file.
XWD X Window System window dump image file.
YUV CCIR 601 4:1:1 file.
YUV3 CCIR-601 4:1:1 files.
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.
Change '-' to '+' in any option above to reverse its effect.
For example, specify +matte to store the image without its
matte channel.
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 DESCRIPTION for a list of valid for-
mats.
When you specify X as your image type, the filename has spe-
cial 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.
Specify input_file as - for standard input, output_file as -
for standard output. If input_file has the extension .Z or
.gz, the file is uncompressed with uncompress or gunzip
respectively. If output_file has the extension .Z or .gz,
the file size is compressed using with compress or gzip
respectively. 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]).
Single images are written with the filename you specify.
However, multi-part images (i.e. a multi-page Postscript
document) are written with the filename followed by a period
(.) and the scene number. You can change this behavior by
embedding a printf format specification in the file name.
For example,
image%02d.miff
converts files image00.miff, image01.miff, etc.
EXAMPLES
To convert a MIFF image of a cockatoo to a SUN raster image,
use:
convert cockatoo.miff sun:cockatoo.ras
To convert a multi-page Postscript document to individual
FAX pages, use:
convert -monochrome document.ps fax:page
To convert a TIFF image to a Postscript A4 page with the
image in the lower left-hand corner, use:
convert -page A4+0+0 image.tiff document.ps
To convert a raw GRAY image to a portable graymap, use:
convert -size 768x512 gray:raw image.pgm
To convert a Photo CD image to a TIFF image, use:
convert -size 1536x1024 img0009.pcd image.tiff
convert img0009.pcd[4] image.tiff
To create a visual image directory of all your JPEG images,
use:
convert 'vid:*.jpg' directory.miff
To annotate an image with blue text using font 12x24 at
position (100,100), use:
convert -font 12x24 -pen blue -geometry +100+100 -anno-
tate "Cockatoo" bird.jpg bird.miff
To tile a 640x480 image with a JPEG texture with bumps use:
convert -size 640x480 tile:bumps.jpg tiled.png
To surround an icon with an ornamental border to use with
Mosaic(1), use:
convert -mattecolor #ccc -frame 6x6 bird.jpg icon.png
OPTIONS
-annotate string
annotate an image with text.
Use this option to annotate an image with text.
Optionally you can include the image filename, type,
width, height, or scene number by embedding special
format characters. Embed %f for filename, %m for mag-
ick, %w for width, %h for height, %s for scene number,
or \n for newline. For example,
-annotate "%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.
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 text position, font, and font color
with -geometry, -font, and -pen respectively. Options
are processed in command line order so be sure to use
-geometry, -font, or -pen before the -annotate option.
-blur factor
blurs an image. Specify factor as the percent enhance-
ment (0.0 - 99.9%).
-border <width>x<height>fP
surround the image with a border or color. See X(1)
for details about the geometry specification.
The color of the border is specified with the -border-
color command line option.
-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 remain unchanged.
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, XYZ, YCbCr,
YIQ, YPbPr, 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 dis-
tances 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.
-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 spe-
cial format characters. Embed %f for 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 com-
ment is read from a file titled by the remaining char-
acters in the string.
-compress type
the type of image compression: QEncoded or RunlengthEn-
coded.
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 <width>{%}x<height>{%}{+-}<x offset>{+-}<y offset>
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 crop a particular area of an image.
Use -crop 0x0 to remove edges that are the background
color.
-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.
-despeckle
reduce the speckles within an image.
-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.
-edge
detect edges with an image.
-emboss
emboss the image.
-enhance
apply a digital filter to enhance a noisy image.
-equalize
perform histogram equalization to the image.
-flip
create a "mirror image" by reflecting the image scan-
lines in the vertical direction.
-flop
create a "mirror image" by reflecting the image scan-
lines in the horizontal direction.
-font name
This option specifies the font to be used for display-
ing normal text. The default is fixed.
-frame <width>x<height>fP
surround the image with an an ornamental border. See
X(1) for details about the geometry specification.
The color of the border is specified with the -mat-
tecolor command line option.
-gamma value
level of gamma correction.
The same color image displayed on two different works-
tations 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 commas (i.e. 1.7,2.3,1.2).
-geometry <width>{%}x<height>{%}{!}
preferred size or location of the image when encoding.
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 dimen-
sions. 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.
There are 72 pixels per inch in Postscript coordinates.
-interlace type
the type of interlacing scheme: NONE, LINE, or PLANE.
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...).
Use LINE, or PLANE to create an interlaced GIF 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, %m for magick, %w for width, %h for height,
or %s for scene number. 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.
-map filename
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. Alter-
natively, you can choose a particular set of colors
with this option.
-matte
store matte channel if the image has one.
-modulate value
vary the brightness, saturation, and hue of an image.
Specify the percent change in brightness, the color
saturation, and the color 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
apply color inversion to image.
The red, green, and blue intensities of an image are
negated.
-noise
reduce the noise in an image with a noise peak
elimination filter.
The principal function of noise peak elimination filter
is to smooth the objects within an image without losing
edge information and without creating undesired struc-
tures. 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.
-normalize
transform image to span the full range of color values.
This is a contrast enhancement technique.
-page <width>x<height>{+-}<x offset>{+-}<y offset>
preferred size and location of the Postscript page.
Use this option to specify the dimensions of the
Postscript page in pixels per inch or a TEXT page in
pixels. The default for a Postscript page is to center
the image on a letter page 612 by 792 pixels. The mar-
gins are 1/2" (i.e. 612x792+36+36). Other common
sizes 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.).
The page geometry is relative to the vertical and hor-
izontal density of the Postscript page. See -density
for details.
To place a Postscript image with a given size on a
given location on a page, use -page +HOFFSET+VOFFSET
-geometry WIDTHxHEIGHT (fill in numbers). Note: this is
only for generating ps, not eps.
The default page dimensions for a TEXT image is
612x792.
-paint
paint the image.
-pen color
set the color of the font. See -annotate for further
details.
See X(1) for details about the color specification.
-quality value
JPEG quality setting.
Quality is 0 (worst) to 100 (best). The default is 85.
-roll {+-}<x offset>{+-}<y offset>
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 degrees
apply Paeth image rotation to the image.
Empty triangles left over from rotating the image are
filled with the color defined as bordercolor (class
borderColor). See X(1) for details.
-sample geometry
scale image with pixel sampling.
-scene value
image scene number.
-sharpen weight
sharpen an image. Specify factor as the percent
enhancement (0.0 - 99.9%).
-shear <x degrees>x<y degrees>
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 direc-
tion 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 <width>{%}x<height>
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
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
-transparency color
make this color transparent within the image.
-treedepth value
Normally, this integer value is zero or one. A zero or
one tells convert to choose a optimal tree depth for
the color reduction algorithm.
An optimal depth generally allows the best representa-
tion 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.
-undercolor <undercolor factor>x<black-generation factor>
control undercolor removal and black generation on CMYK
images.
This option enables you to perform undercolor removal
and black generation on CMYK images-- images to be
printed on a four-color printing system. You can con-
trol how much cyan, magenta, and yellow to remove from
your image and how much black to add to it. The stan-
dard undercolor removal is 1.0x1.0. You'll frequently
get better results, though, if the percentage of black
you add to your image is slightly higher than the per-
centage of C, M, and Y you remove from it. For example
you might try 0.5x0.7.
-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 to read
and convert the image.
ENVIRONMENT
DISPLAY
To get the default host, display number, and screen.
SEE ALSO
display(1), animate(1), import(1), montage(1), mogrify(1),
segment(1), combine(1), xtp(1)
COPYRIGHT
Copyright 1995 E. I. du Pont de Nemours and 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 docu-
mentation, and that the name of E. I. du Pont de Nemours and
Company not be used in advertising or publicity pertaining
to distribution of the software without specific, written
prior permission. E. I. du Pont de Nemours and 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 and Company disclaims all warran-
ties with regard to this software, including all implied
warranties of merchantability and fitness, in no event shall
E. I. du Pont de Nemours and Company be liable for any spe-
cial, indirect or consequential damages or any damages what-
soever resulting from loss of use, data or profits, whether
in an action of contract, negligence or other tortuous
action, arising out of or in connection with the use or per-
formance of this software.
AUTHORS
John Cristy, E.I. du Pont De Nemours and Company Incor-
porated