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Linux / Unix Command: convert
Command Library

NAME

convert - convert an image or sequence of images

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. In addition, various types of image processing can be performed on the converted image during the conversion process. Convert recognizes the image formats listed in ImageMagick(1).

EXAMPLES

To make a thumbnail of a JPEG image, use:


convert -size 120x120 cockatoo.jpg -resize 120x120
+profile '*' thumbnail.jpg

In this example, "-size 120x120" gives a hint to the JPEG decoder that the image is going to be downscaled to 120x120, allowing it to run faster by avoiding returning a full-resolution image. The "-resize 120x120" specifies the desired dimensions of the output image. It will be scaled so its largest dimension is 120 pixels. The "+profile '*'" removes any ICM, EXIF, IPTC, or other profiles that might be present in the input and aren't needed in the thumbnail.

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 with a 128 byte header to a portable graymap, use:


convert -depth 8 -size 768x512+128 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 helvetica -fill blue
-draw "text 100,100 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 "#697B8F" -frame 6x6 bird.jpg
icon.png

To create a MNG animation from a DNA molecule sequence, use:


convert -delay 20 dna.* dna.mng

OPTIONS

Options are processed in command line order. Any option you specify on the command line remains in effect for the set of images that follows, until the set is terminated by the appearance of any option or -noop. Some options only affect the decoding of images and others only the encoding. The latter can appear after the final group of input images.

For a more detailed description of each option, see ImageMagick(1).

-adjoin
join images into a single multi-image file
-affine
drawing transform matrix
-antialias
remove pixel aliasing
-append
append a set of images
-average
average a set of images
-background
the background color
-blur x
blur the image with a gaussian operator
-border x
surround the image with a border of color
-bordercolor
the border color
-box
set the color of the annotation bounding box
-cache
megabytes of memory available to the pixel cache
-channel
the type of channel
-charcoal
simulate a charcoal drawing
-chop x{+-}{+-}{%}
remove pixels from the interior of an image
-clip
apply the clipping path, if one is present
-coalesce
merge a sequence of images
-colorize
colorize the image with the pen color
-colors
preferred number of colors in the image
-colorspace
the type of colorspace
-comment
annotate an image with a comment
-compose
the type of image composition
-compress
the type of image compression
-contrast
enhance or reduce the image contrast
-crop x{+-}{+-}{%}
preferred size and location of the cropped image
-cycle
displace image colormap by amount
-debug
enable debug printout
-deconstruct
break down an image sequence into constituent parts
-delay <1/100ths of a second>
display the next image after pausing
-density x
vertical and horizontal resolution in pixels of the image
-depth
depth of the image
-despeckle
reduce the speckles within an image
-display
specifies the X server to contact
-dispose
GIF disposal method
-dither
apply Floyd/Steinberg error diffusion to the image
-draw
annotate an image with one or more graphic primitives
-edge
detect edges within an image
-emboss
emboss an image
-encoding
specify the font encoding
-endian
specify endianness (MSB or LSB) of output image
-enhance
apply a digital filter to enhance a noisy image
-equalize
perform histogram equalization to the image
-fill
color to use when filling a graphic primitive
-filter
use this type of filter when resizing an image
-flatten
flatten a sequence of images
-flip
create a "mirror image"
-flop
create a "mirror image"
-font
use this font when annotating the image with text
-frame x++
surround the image with an ornamental border
-fuzz {%}
colors within this distance are considered equal
-gamma
level of gamma correction
-gaussian x
blur the image with a gaussian operator
-geometry x{+-}{+-}{%}{@} {!}{<}{>}
preferred size and location of the Image window.
-gravity
direction primitive gravitates to when annotating the image.
-help
print usage instructions
-implode
implode image pixels about the center
-intent
use this type of rendering intent when managing the image color
-interlace
the type of interlacing scheme
-label
assign a label to an image
-level
adjust the level of image contrast
-list
the type of list
-loop
add Netscape loop extension to your GIF animation
-map
choose a particular set of colors from this image
-mask
Specify a clipping mask
-matte
store matte channel if the image has one
-median
apply a median filter to the image
-modulate
vary the brightness, saturation, and hue of an image
-monochrome
transform the image to black and white
-morph
morphs an image sequence
-mosaic
create a mosaic from an image sequence
-negate
replace every pixel with its complementary color
-noise
add or reduce noise in an image
-noop
NOOP (no option)
-normalize
transform image to span the full range of color values
-opaque
change this color to the pen color within the image
-page x{+-}{+-}{%}{!}{<}{>}
size and location of an image canvas
-paint
simulate an oil painting
-pen
specify the pen color for drawing operations
-ping
efficiently determine image characteristics
-pointsize
pointsize of the Postscript, OPTION1, or TrueType font
-preview
image preview type
-process
process a sequence of images
-profile
add ICM, IPTC, or generic profile to image
-quality
JPEG/MIFF/PNG compression level
-raise x
lighten or darken image edges
-region x{+-}{+-}
apply options to a portion of the image
-resize x{%}{@}{!}{<}{>}
resize an image
-roll {+-}{+-}
roll an image vertically or horizontally
-rotate {<}{>}
apply Paeth image rotation to the image
-sample
scale image with pixel sampling
-sampling_factor x
sampling factors used by JPEG or MPEG-2 encoder and YUV decoder/encoder.
-scale
scale the image.
-scene
set scene number
-seed
pseudo-random number generator seed value
-segment x
segment an image
-shade x
shade the image using a distant light source
-sharpen x
sharpen the image
-shave x
shave pixels from the image edges
-shear x
shear the image along the X or Y axis
-size x{+offset}
width and height of the image
-solarize
negate all pixels above the threshold level
-spread
displace image pixels by a random amount
-stroke
color to use when stroking a graphic primitive
-strokewidth
set the stroke width
-swirl
swirl image pixels about the center
-texture
name of texture to tile onto the image background
-threshold
threshold the image
-tile
tile image when filling a graphic primitive
-transform
transform the image
-transparent
make this color transparent within the image
-treedepth
tree depth for the color reduction algorithm
-trim
trim an image
-type
the image type
-units
the type of image resolution
-unsharp x
sharpen the image with an unsharp mask operator
-use_pixmap
use the pixmap
-verbose
print detailed information about the image
-view
FlashPix viewing parameters
-wave x
alter an image along a sine wave
-write
write an image sequence [convert, composite]

For a more detailed description of each option, see ImageMagick(1).

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:


Build a histogram, one for each color component of the image.
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.
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.
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

display(1), animate(1), identify(1), ImageMagick(1), montage(1), mogrify(1), composite(1)


Important: Use the man command (% man) to see how a command is used on your particular computer.

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