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Linux / Unix Command: convert
Command Library


convert - convert an image or sequence of images


convert [ options ... ] input_file output_file


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).


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

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

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

convert -delay 20 dna.* dna.mng


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).

join images into a single multi-image file
drawing transform matrix
remove pixel aliasing
append a set of images
average a set of images
the background color
-blur x
blur the image with a gaussian operator
-border x
surround the image with a border of color
the border color
set the color of the annotation bounding box
megabytes of memory available to the pixel cache
the type of channel
simulate a charcoal drawing
-chop x{+-}{+-}{%}
remove pixels from the interior of an image
apply the clipping path, if one is present
merge a sequence of images
colorize the image with the pen color
preferred number of colors in the image
the type of colorspace
annotate an image with a comment
the type of image composition
the type of image compression
enhance or reduce the image contrast
-crop x{+-}{+-}{%}
preferred size and location of the cropped image
displace image colormap by amount
enable debug printout
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 of the image
reduce the speckles within an image
specifies the X server to contact
GIF disposal method
apply Floyd/Steinberg error diffusion to the image
annotate an image with one or more graphic primitives
detect edges within an image
emboss an image
specify the font encoding
specify endianness (MSB or LSB) of output image
apply a digital filter to enhance a noisy image
perform histogram equalization to the image
color to use when filling a graphic primitive
use this type of filter when resizing an image
flatten a sequence of images
create a "mirror image"
create a "mirror image"
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
level of gamma correction
-gaussian x
blur the image with a gaussian operator
-geometry x{+-}{+-}{%}{@} {!}{<}{>}
preferred size and location of the Image window.
direction primitive gravitates to when annotating the image.
print usage instructions
implode image pixels about the center
use this type of rendering intent when managing the image color
the type of interlacing scheme
assign a label to an image
adjust the level of image contrast
the type of list
add Netscape loop extension to your GIF animation
choose a particular set of colors from this image
Specify a clipping mask
store matte channel if the image has one
apply a median filter to the image
vary the brightness, saturation, and hue of an image
transform the image to black and white
morphs an image sequence
create a mosaic from an image sequence
replace every pixel with its complementary color
add or reduce noise in an image
NOOP (no option)
transform image to span the full range of color values
change this color to the pen color within the image
-page x{+-}{+-}{%}{!}{<}{>}
size and location of an image canvas
simulate an oil painting
specify the pen color for drawing operations
efficiently determine image characteristics
pointsize of the Postscript, OPTION1, or TrueType font
image preview type
process a sequence of images
add ICM, IPTC, or generic profile to image
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
scale image with pixel sampling
-sampling_factor x
sampling factors used by JPEG or MPEG-2 encoder and YUV decoder/encoder.
scale the image.
set scene number
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
negate all pixels above the threshold level
displace image pixels by a random amount
color to use when stroking a graphic primitive
set the stroke width
swirl image pixels about the center
name of texture to tile onto the image background
threshold the image
tile image when filling a graphic primitive
transform the image
make this color transparent within the image
tree depth for the color reduction algorithm
trim an image
the image type
the type of image resolution
-unsharp x
sharpen the image with an unsharp mask operator
use the pixmap
print detailed information about the image
FlashPix viewing parameters
-wave x
alter an image along a sine wave
write an image sequence [convert, composite]

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


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.


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.

>> Linux/Unix Command Library

>> Shell Command Library

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