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The ROI pane deals with region of interest operations.  
Such operations are useful for executing image processing routines on
particular regions of an image.  
Using ROI functions, one is able to extract regions of an image, insert 
subimages into an image, and execute image processing routines 
on the region of interest.
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.IP "1)  Insert/Extract Mode & Position Parameters:"
Region of Interest Operations may be done either with the mouse, or via
the keyboard.  If keyboard placement is chosen, the position and size of
the region of interest is specified by entering values to define
the upper left hand corner of the rectangle, and its width and height.
Only if the keyboard method is used does one need to fill
out the "Upper Left x", "Upper Left y", "Width", and "Height" parameters.
When the mouse method is used, these parameters are specified interactively
by using the mouse.
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.IP "2)  Insert Region of Interest (read):"
"Insert Region of Interest" reads in the specified input file and inserts it
into the displayed image.  To insert a region of interest, enter the desired
image name and hit the <cr> key.
When the region of interest comes up, it is outlined
by a bounding box.  The region of interest may be moved to the desired position
by dragging its bounding box with the mouse. NOTE: sometimes the bounding
box is difficult to see.  Images that are larger than the image 
being displayed cannot be inserted.
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.IP "3)  Extract Region of Interest (write):"
The "Extract Region of Image" function allows the user to specify 
a region of the image being displayed for manipulation.
The subimage may either be saved as a new image, or be operated on using image 
processing routines. Later, it may be inserted back into the displayed image. 
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To specify the output image name, either type the file name in via the keyboard,
or use the browser.  Hitting <cr> in the parameter box will initiate the 
extraction.
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If the image is to be extracted by mouse, crosshairs will appear in the display
window which can be moved around by placing the mouse cursor on 
a line, pressing the mouse button, and dragging.
Either vertical cross hair can be used to define the right and left sides
of the subimage, and either horizontal crosshair can be used to define 
the top and bottom of the subimage.  
An alternate way to define the subimage boundaries is to drag the mouse at 
the intersection of two crosshairs.  This will drag a corner of the subimage
boundary.  Note:  Sometimes the cross hairs are difficult to see.
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.IP "4)  ROI COMMANDS:"
This function allows the user to perform image processing routines on a 
\fIselected\fP region of interest.  The region is selected by performing
the "Extract Subimage" command. Once a region has been 
extracted, the region can be processed in three ways:
.RS
.IP a.  4
Click on the ROI COMMANDS button. Select one of the functions
in the ROI Operations pane by clicking on that operation name.  This will 
execute the function on the region of interest. The region of interest will
then be inserted  back into the main image.  If the "Command Options:" logical
selection reads, "Use Defaults", using the ROI functions in this way will 
execute the selected image processing routine using the routine's default values.
Descriptions of the image processing  routines and the default values can
be found by reading the man page for that particular routine name.
.IP b.  4
Click on the ROI COMMANDS button. Select one of the functions
in the ROI Operations pane by clicking on that operation name.  This will
execute the function on the region of interest. The region of interest will
then be inserted  back into the main image.   If the "Command Options:" logical
selection reads, "User Defined", a text box will come up, in which you will
be prompted to enter values for function argument.  Using this method,
you can execute the image processing routines using non-default values;
however, you must provide an accurate call to the desired image processing 
routine, just as you would if you were executing it from the command line.
.IP c. 4
The third method of manipulating an extracted image is to save the extracted
image, enter cantata, and perform image processing routines in the
cantata visual language environment.  Once the subimage has been manipulated, 
it can be reinserted into the original image by using the "Insert Region of 
Interest" command in \fBeditimage\fP.
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.LP
WARNING: Application of image processing routines to a ROI voids all prior 
colormap operations; therefore, the image should first be saved, 
otherwise the changes will be lost during this operation.  This occurs because
ROI operations can create pixels with unknown LUT or colormap values, 
therefore the entire image is mapped according to a linear LUT.
