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[ #usageExample Usage  | #optionsOption Summary ]
Use the compare program to mathematically and visually annotate the difference between an image and its reconstruction.  See ../www/command-line-processing.htmlCommand 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.jpgrose   
../images/reconstruct.jpgrose   
==>  
../images/difference.pngrose 
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-428Graphics from the Command Line .  Further discussion is available in http://www-106.ibm.com/developerworks/library/l-graf2/?ca=dgr-lnxw15GraphicsLineMore Graphics from the Command Line  and http://www.cit.gu.edu.au/~anthony/graphics/imagick6Examples 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#identify–identify     
identify the format and characteristics of the image   
  
    
../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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