Content-type: text/html Manpage of cgcurs


Section: User Commands (1)
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cgcurs - Read quantities with cursor from images on a PGPLOT device  






CGCURS displays an image via a contour plots or a pixel map representation (formerly called a "grey scale") on a PGPLOT device. The cursor is then used to read image values, or to evaluate image statistics in a polygonal region, or to write a polygonal region definition to a text file.

Manipulation of the device colour lookup table is available when you display with a pixel map representation.

When using cursor options, generally, click the right button (enter X) to exit the function, click the left button (enter A) to add a location, and click the middle button (enter D) to delete a location.  


One or two input images may be specified. If two, and TYPE=both, then the first is used as the background image, and the second for a contour overlay. They must match in size.
Specifies the type of the image(s) in the IN keyword. Minimum match is supported:

  "pixel": pixel map (formerly "grey" which is still supported),
"contour": contour plot,
   "both": first input image is pixel map, the second is contour
           overlay.  If only one input image was specified it is
           used for both.

Default is "pixel" if one input image is specified, else "both".

Region of interest. Choose only one spatial region (bounding box only supported), but as many spectral regions (i.e., multiple IMAGE specifications) as you like. If you display a 3-D image, the cursor options are activated after each sub-plot (channel or group of channels; see CHAN below) is drawn. Default is full image
Up to 4 values. These give the spatial increment and binning size in pixels for the x and y axes to be applied to the selected region. If the binning size is not unity, it must equal the increment. For example, to bin up the image by 4 pixels in the x direction and to pick out every third pixel in the y direction, set XYBIN=4,4,3,1. Defaults are 1,XYBIN(1),XYBIN(1),XYBIN(3)
2 values. The first is the channel increment, the second is the number of channels to average, for each sub-plot. Thus CHAN=5,3 would average groups of 3 channels together, starting 5 channels apart such as: 1:3, 6:8, 11:13 ... The channels available are those designated by the REGION keyword. A new group of channels (sub-plot) is started if there is a discontinuity in the REGION selected channels (such as IMAGE(10,20),IMAGE(22,30).

Defaults are 1,1

2 values. First value is the type of contour level scale factor. "p" for percentage and "a" for absolute. Second value is the level to scale LEVS by. Thus SLEV=p,1 would contour levels at LEVS * 1% of the image peak intensity. Similarly, SLEV=a,1.4e-2 would contour levels at LEVS * 1.4E-2 Default is no additional scaling of LEVS
Levels to contour for first image, are LEVS times SLEV (either percentage of the image peak or absolute). Defaults try to choose something sensible
3 values. The pixel map range (background to foreground), and transfer function type. The transfer function type can be one of "lin" (linear), "log" (logarithmic), "heq" (histogram equal- ization), and "sqr" (square root). See also OPTIONS=FIDDLE which is in addition to the selections here.

Default is linear between the image minimum and maximum If you wish to just give a transfer function type, set range=0,0,heq say.

The PGPLOT plot device, such as plot.plt/ps. No default.
Number of sub-plots in the x and y directions on the page. Defaults choose something sensible
Two values. The spatial label type of the x and y axes. Minimum match is active. Select from:

"hms" the label is in H M S (e.g. for RA) "dms" the label is in D M S (e.g. for DEC) "arcsec" the label is in arcsecond offsets "arcmin" the label is in arcminute offsets "absdeg" the label is in degrees "reldeg" the label is in degree offsets

            The above assume the  pixel increment is in radians.
"abspix" the label is in pixels "relpix" the label is in pixel offsets "abskms" the label is in Km/s "relkms" the label is in Km/s offsets "absghz" the label is in GHz "relghz" the label is in GHz offsets "absnat" the label is in natural coordinates as defined by
            the header.
"relnat" the label is in offset natural coordinates

All offsets are from the reference pixel. Defaults are "abspix", LABTYP(1) unless LABTYP(1)="hms" whereupon LABTYP(2) defaults to "dms" (for RA and DEC).

Task enrichment options. Minimum match is active.

"abspix" means write the region of interest in absolute integer

  pixels instead of arcseconds relative to the reference pixel.
"box" When in "CURSOR" mode, rather than listing the value of
  the of the pixel under the cursor, list the peak value in a
  5x5 pixel box centred on the pixel under the cursor.
"cgspec" With OPTIONS=CURSOR and LOGFILE, the output log file
  is is one with commands appropriate for input to CGSPEC's OLAY
"cgdisp" With OPTIONS=CURSOR and LOGFILE, the output log file
  is one with commands appropriate for input to CGDISP's OLAY

  Note that if you specify both CGSPEC and CGDISP then lines
  appropriate to both these programs are written into the log
  file.  You can then copy the log file and retain the CGDISP
  lines in one file, and the CGSPEC lines in the other.
"cursor" means that after drawing each sub-plot, a cursor will
  be displayed; striking any key or clicking the relevant mouse
  button (left) causes the location and value of the pixel under
  the cursor to be listed on the terminal.   On terminals, enter
  "x" to exit the cursor.  On workstations, click the relevant
  button (generally the right one).
"fiddle" means enter a routine to allow you to interactively
  change the display lookup table.  You can cycle through b&w
  and colour displays, as well as alter the transfer function by
  the cursor location, or by selecting predefined transfer
  functions such as histogram equalization, logarithmic, and
  square root.
"grid" means draw a coordinate grid on the plot rather than just
"logfile" When the "cursor" or "stats" are activated, then this
  writes the results to log files (cgcurs.curs and cgcurs.stat)
  as well as the screen.
"mark" When in "CURSOR" mode, mark the locations selected. If
  OPTIONS=STATS is activated, mark the minimum and maximum pixel
  locations too.
"nearest" When the cursor is used to select a location, force
  that location to be the nearest image pixel, rather than the
  default which allows fractional pixel locations.
"noerase" Don't erase a snugly fitting rectangle into which the
  "3-axis" value string is written.
"region" means use the cursor to define a polygonal region that
  gets gets written to a log file as the REGION keyword.  The
  cursor behaves as described above for the "stats" option.  You
  can the use this in other programs as "region=@filename"
"stats" means that after drawing each sub-plot, you get the
  opportunity to define a polygonal region with the cursor (A to
  add a vertex, D to delete the previous vertex, X to exit; or
  use the three mouse buttons) inside of which image statistics
  are evaluated.
"trlab" means label the top and right axes as well as the bottom
  and left ones.  This can be useful when non-linear coordinate
  variation across the field makes the ticks misaligned
"unequal" means draw plots with unequal scales in x and y. The
  default is that the scales are equal.
"wedge" means that if you are drawing a pixel map, also draw
  and label a wedge to the right of the plot, showing the map
  of intensity to colour
"3value" means label each sub-plot with the appropriate value
  of the third axis (e.g. velocity or frequency for an xyv
  ordered cube, position for a vxy ordered cube).
"3pixel" means label each sub-plot with the pixel value of the
  the third axis.   Both "3pixel" and "3value" can appear, and
  both will be written on the plot.  They are the average values
  when the third axis is binned up with CHAN.  If the third axis
  is not velocity or frequency, the units type for "3VALUE" will
  be chosen to be the complement of any like axis in the first
  two.  E.g., the cube is in vxy order and LABTYP=ABSKMS,ARCSEC
  the units for the "3VALUE" label will be arcsec.  If
  LABTYP=ABSKMS,HMS the "3VALUE" label will be DMS (if the third
  [y] axis is declination).
If you ask for "3value" labelling, this keyword allows you specify the FORTRAN format of the labelling. I have given up trying to invent a decent algorithm to choose this. Examples are "1pe12.6", or "f5.2" etc If you leave this blank cgdisp will try something that you probably won't like.
Two values. Character sizes in units of the PGPLOT default (which is ~ 1/40 of the view surface height) for the plot axis labels and the velocity/channel labels. Defaults choose something sensible.




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Time: 18:35:38 GMT, July 05, 2011