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#usage
Example Usage
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#options
Option Summary
]
Use the
compare
program to mathematically and visually annotate the difference between an image and its reconstruction.  See
../www/command-line-processing.html
Command Line Processing
for advice on how to structure your
compare
command or see below for example usages of the command.
Example Usage
We list a few examples of the
compare
command here to illustrate its usefulness and ease of use. To get started, lets compare an image to one thats been sharpened:
convert rose.jpg -sharpen 0x1 reconstruct.jpg
compare rose.jpg reconstruct.jpg difference.png
../images/rose.jpg
rose
../images/reconstruct.jpg
rose
==>
../images/difference.png
rose
The red areas of the difference image show which pixels were affected by the image sharpening, whereas, white is areas that were untouched by the sharpening process
In addition to the visual interpretation of the difference in an image and its reconstruction, we report a mathematical measure of the difference :
compare -metric PSNR rose.jpg reconstruct.jpg difference.png
29.5615 dB
You can find additional examples of using
compare
in
http://www-106.ibm.com/developerworks/library/l-graf/?ca=dnt-428
Graphics from the Command Line
.  Further discussion is available in
http://www-106.ibm.com/developerworks/library/l-graf2/?ca=dgr-lnxw15GraphicsLine
More Graphics from the Command Line
and
http://www.cit.gu.edu.au/~anthony/graphics/imagick6
Examples of ImageMagick Usage
.
Option Summary
The
compare
command recognizes these options.  Click on an option to get more details about how that option works.
Option
Description
../www/command-line-options.html#authenticate
-authenticate
value
decrypt image with this password
../www/command-line-options.html#channel
-channel
type
apply option to select image channels
../www/command-line-options.html#colorspace
-colorspace
type
alternate image colorspace
../www/command-line-options.html#debug
-debug
events
display copious debugging information
../www/command-line-options.html#define
-define
format:option
define one or more image format options
../www/command-line-options.html#density
-density
geometry
horizontal and vertical density of the image
../www/command-line-options.html#depth
-depth
value
image depth
../www/command-line-options.html#extract
-extract
geometry
extract area from image
../www/command-line-options.html#help
-help
print program options
../www/command-line-options.html#interlace
-interlace
type
type of image interlacing scheme
../www/command-line-options.html#limit
-limit
type value
pixel cache resource limit
../www/command-line-options.html#log
-log
format
format of debugging information
../www/command-line-options.html#metric
-metric
type
measure differences between images with this metric
../www/command-line-options.html#profile
-profile
filename
add, delete, or apply an image profile
../www/command-line-options.html#quality
-quality
value
JPEG/MIFF/PNG compression level
../www/command-line-options.html#quiet
-quiet
suppress all error or warning messages
../www/command-line-options.html#sampling-factor
-sampling-factor
geometry
horizontal and vertical sampling factor
../www/command-line-options.html#set
-set
attribute value
set an image attribute
../www/command-line-options.html#size
-size
geometry
width and height of image
../www/command-line-options.html#verbose
-verbose
print detailed information about the image
../www/command-line-options.html#version
-version
print version information
../www/command-line-options.html#virtual-pixel
-virtual-pixel
method
access method for pixels outside the boundaries of the image
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