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IMGWIN

IMGWIN

Name


      IMGWIN

Purpose



      This is an image display routine to allow the user to interact with
      an image. Moving the cursor in the window gives the value and location
      inside the image. The image is enclosed in a SCALEIMAGE object, so many of
      the input keywords are used to set the scaling parameters for that object.
      If axes are requested, an IMGAXIS object is added to the SCALEIMAGE object.
      Other keywords are used to set up the axis object. The entire window can
      be saved to file in various formats. The image can be scaled interactively,
      image colors can be changed, and various image and axes properties can be
      accessed directly from the File menu of the image window.
     

Authors



        FANNING SOFTWARE CONSULTING BURRIDGE COMPUTING
        1645 Sheely Drive 18 The Green South
        Fort Collins Warborough, Oxon
        CO 80526 USA OX10 7DN, ENGLAND
        Phone: 970-221-0438 Phone: +44 (0)1865 858279
        E-mail: davidf@dfanning.com E-mail: davidb@burridgecomputing.co.uk

Category



      Graphics display.

Syntax



      ImgWin, image
     

Arguments


 
    image An 8-bit or 24-bit image array, or the name of an image file that
              can be opened with READ_IMAGE.
     

Input Keywords



    AXES: Set this keyword to draw a set of axes around the image.
    BACKGROUND: This keyword specifies the name of a background color. By default, 'ivory'.
    BETA: The beta factor in a Hyperpolic Sine stretch. Default is 3.0.
    BOTTOM: The lowest value of the scaled image.
   
    BREWER: Set if the color table index number (CT) is the index of a Brewer color table.
                  To use Brewer color tables, the file fsc_brewer.tbl must be in your IDL path.
                 
    COLOR: Set this keyword to the name of the axis color. The name is passed to cgColor
                  for processing. Default is "charcoal". Used only if AXES is set.
    CTINDEX: The index of the color table to use to display the image. Applies only to
                  2D image arrays. By default, 0, gray scale. If set to -1, uses current color table.
    EXPONENT: The logarithm exponent in a logarithmic stretch. Default is 4.0.
   
    FULL_RESOLUTION: Set this keyword if you want the image to be displayed in its full, native resolution.
                  If this keyword is set, the XSIZE and YSIZE keywords set the scrollable window size.
    GAMMA: The gamma factor in a gamma stretch. Default is 1.5.
    KEEP_ASPECT: Normally, the image will be resized to fit the specified position in the
                  window. If you prefer, you can force the image to maintain its aspect ratio
                  in the window (although not its natural size) by setting this keyword.
                  The image width is fitted first. If, after setting the image width, the image
                  height is too big for the window, then the image height is fitted into the window.
                  The appropriate values of the POSITION keyword are honored during this fitting
                  process. Once a fit is made, the POSITION coordiates are re-calculated to center
                  the image in the window. You can recover these new position coordinates as the
                  output from the POSITION keyword. This keyword is turned ON by default. In other
                  words, to allow free positioning, set KEEP_ASPECT=0. Note that if this keyword is
                  set, and the XSIZE and YSIZE keywords are undefined, that the window will have the
                  same aspect ratio as the image.
                 
    MAP_COORD: A MapCoord object that can be used to georeference the image in the display window.
    MAP_GRID: If the file can be georegistered (e.g. a GeoTIFF file), then setting this keyword
                  will add a map grid to the MapCoord object. Otherwise, the keyword is
                  ignored. Can only be used when passing ImgWin a GeoTIFF filename.
    MAP_OUTLINE: If the file can be georegistered (e.g. a GeoTIFF file), then setting this keyword
                  will add a continental outline to the MapCoord object. Otherwise, the keyword is
                  ignored. Can only be used when passing ImgWin a GeoTIFF filename.
                 
    MEAN: The mean factor in a logarithmic stretch. Default is 0.5.
    MISSING_COLOR: The name of the missing color. The default is "gray".
    MISSING_VALUE: The number that represents missing value in the image.
    NCOLORS: The number of colors to scale the data into, as in this: (Default: 256)
                      displayImage = BYTSCL(image, MIN=self.sclmin, MAX=self.sclmax, TOP=self.ncolors-1)
    NOINTERP: Setting this keyword disables the default bilinear
                    interpolation done to the image when it is resized. Nearest
                    neighbor interpolation is done instead. This is preferred
                    when you do not wish to change the pixel values of the image.
                    This keyword is turned ON by default. In other words, to allow
                    interpolation, set NOINTERP=0.
    POSITION: The position of the image in the display window. The position is given
                    as a four-element array in normalized (0 to 1) coordinates of the form
                    [x0, y0, x1, y1], where (x0,y0) is the lower-left corner of the image and
                    (x1,y1) is the upper-right corner of the image. If the KEEP_ASPECT keyword
                    is set, the image will be located within the specified POSITION in a way
                    that preserves the aspect ratio of the image. The default is [0.075, 0.075, 0.925, 0.925].
                   
                   
    SCALETYPE: The type of scaling performed prior to display. Default is 0, linear scaling.
                    May be specified as a number or as a string (e.g, 3 or "ASINH").
          Number Type of Stretch
            0 Linear scaled = BytScl(image, MIN=minThresh, MAX=maxThresh)
            1 Gamma scaled = GmaScl(image, MIN=minThresh, MAX=maxThresh, Gamma=gamma)
            2 Log scaled = LogScl(image, MIN=minThresh, MAX=maxThresh, Mean=mean, Exponent=exponent)
            3 Asinh scaled = AsinhScl(image, MIN=minThresh, MAX=maxThresh, Beta=beta)
            4 Linear 2% A linear stretch, with 2 percent of pixels clipped at both the top and bottom
            5 Square Root A linear stretch of the square root histogram of the image values.
            6 Equalization A linear stretch of the histogram equalized image histogram.
            7 Gaussian A Gaussian normal function is applied to the image histogram.
            8 None No scaling whatsoever is done.
    SCLMIN: The image data is scaled between SCLMIN and SCLMAX before display. Default = 0.
    SCLMAX: The image data is scaled between SCLMIN and SCLMAX before display. Default = 255.
    SIGMA: The sigma scale factor for Gaussian scaling. Default is 1.0.
   
    TLB_TITLE: The title of the IMGWIN top-level base. Default: "Catalyst Image Window
   
    WIN_KEEP_ASPECT: If this keyword is set, the IMGWIN window will maintain the same aspect ratio
                    as the image as it is resized.
   
    XRANGE: If the AXES keyword is set, this keyword is a two-element vector
                    giving the X axis range. By default, [0, size of image in X].
                   
    XSIZE: The X size of the initial image window. If undefined, appoximately 600 pixels.
                    (Acutally size determined by the aspect ratio of the image.)
                   
    XTICKFORMAT: The tick formatting for the X axis, if the AXES keyword is set.
                   
    XTILE: The title of the X axis, if the AXES keyword is set.
    YRANGE: If the AXES keyword is set, this keyword is a two-element vector
                    giving the Y axis range. By default, [0, size of image in Y].
                   
    YSIZE: The Y size of the initial image window. If undefined, appoximately 600 pixels.
                    (Acutally size determined by the aspect ratio of the image.)
    YTICKFORMAT: The tick formatting for the Y axis, if the AXES keyword is set.
                   
    YTILE: The title of the Y axis, if the AXES keyword is set.
   

Output Keywords


 
    OUTIMAGE: The image object that is created inside the program.

Modification History



      Written by: David W. Fanning, 12 October 2008.
      Fixed a problem with no image updates after writing the image to PostScript output. 8 Nov 2008. DWF.
      Whoops! Fixed a problem with the KEEP_ASPECT keyword not working. 11 Dec 2008. DWF.
      Added WIN_KEEP_ASPECT to allow the display window to keep the same aspect ratio as the image
          upon resize. 11 Dec 2008. DWF.
      A change to XStretch on 15 March revealed a small bug in the way XStretch was being called
          in IMGWIN. It is now being called with the proper keywords. 18 March 2009. DWF.
      Fixed a small problem with the way the CTINDEX keyword was handled. 8 May 2009. DWF.
      PNG files with more than 8-bits per channel are now being handled correctly. 5 August 2009. DWF.
      Modified to georegister GEOTIFF files when they are opened via a GeoTIFF file name. 30 August 2009. DWF.
      Modified code so that input parameter data type would not change. 13 December 2009. DWF.
      Fixed a problem with the image variable name when the name of a GeoTIFF is passed to
          the program. 10 February 2010. DWF.
      Fixed a problem with CTINDEX=-1 not working when passed GeoTIFF files. 21 Febrary 2010. DWF.
      Added AUTODRAWGRID keyword to MAP_GRID calls. 11 March 2010.
      Overly ambitious cleanup was killing passed in map coordinate variable Fixed. 24 March 2010. DWF.



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