gm compare

The latest GM 1.3 development snapshot (GraphicsMagick-1.3.020080807) 
now introduces a 'compare' utility.  There is no documentation yet 
other than the help message:

Usage: gm compare [options ...] reference [options ...] compare [options ...]

Where options include:
   -algorithm algorithm differencing algorithm (Annotate, Threshold)
   -authenticate value  decrypt image with this password
   -colorspace type     alternate image colorspace
   -debug events        display copious debugging information
   -define values       Coder/decoder specific options
   -density geometry    horizontal and vertical density of the image
   -depth value         image depth
   -algorithm algorithm differencing algorithm (Annotate, Threshold)
   -display server      get image or font from this X server
   -endian type         LSB, MSB, or Native
   -file filename       write difference image to this file
   -help                print program options
   -highlight-color color
                        color to use when annotating difference pixels
   -interlace type      None, Line, Plane, or Partition
   -limit type value    Disk, Files, Map, Memory, or Pixels resource limit
   -log format          format of debugging information
   -matte               store matte channel if the image has one
   -metric              comparison metric (MAE, MSE, PAE, PSNR, RMSE)
   -monitor             show progress indication
   -sampling-factor HxV[,...]
                        horizontal and vertical sampling factors
   -size geometry       width and height of image
   -type type           image type
   -verbose             print detailed information about the image
   -version             print version information

Here are some usage cases:

% gm compare seaworld.tiff seaworld2.jpg -metric pae
Image Difference (PeakAbsoluteError):
            Normalized    Absolute
           ============  ==========
      Red: 0.0117647059      771.0
    Green: 0.0117647059      771.0
     Blue: 0.0156862745     1028.0
    Total: 0.0156862745     1028.0

% gm compare -algorithm Threshold seaworld.tiff seaworld2.jpg -file diff.miff

Any and all feedback is welcomed.

Bob
======================================
Bob Friesenhahn
[email protected], http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/


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