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cgdisp - Displays and overlays images on a PGPLOT device  






CGDISP displays/overlays images via contour plots, pixel map representations, vectors and scaled boxes on a PGPLOT device. Upto 3 contour plots, one pixel map, one vector plot and one box display may be overlaid in multi-panel plots of multi-channel images. In addition overlay locations (plotted as crosses, boxes, circles, lines or see-through) may be specified from an ascii text file.

Manipulation of the device colour lookup table is available when you display with a pixel map representation (formerly called a "grey scale")  


You may input up to seven images. Up to three of these can be displayed via contour plots and one can be displayed via a colour pixel map representation. One vector amplitude image and one vector position angle image (degrees; positive N -> E) can together be used to display a vector map (e.g. polarization vectors). One image can be displayed as small scaled boxes (see below) and one image may be used as a mask.

The "box" image is displayed by drawing little boxes (solid and hollow for positive and negative pixels) at the location of each selected pixel. The size of the box scales with the value of the pixel. This is a useful way to display rotation measure images for example. The mask image blanking mask is logically ANDed to all the other image masks before they are displayed. The mask image is not displayed.

If more than one image is specified, they must have identical first and second dimensions. However, you can overlay combinations of 2-D with 3-D images (e.g. multi-channel images with a continuum image) provided all the 3-D images have the same third dimension. These images can be input in any order (see TYPE). Wild card expansion is supported. No default.

Specifies the type of each image, respectively, listed in the IN keyword. Minimum match is supported (note that "pixel" was formerly "grey" [which is still supported]). Choose from:

 "contour"   (contour;            up to 3 of these)
 "pixel"     (pixel map;          up to 1 of these)
 "amplitude" (vector amplitude;   up to 1 of these)
 "angle"     (vector pos'n angle; up to 1 of these)
 "box"       (box;                up to 1 of these)
 "mask"      (mask;               up to 1 of these)

You can't give one of "amplitude" or "angle" without the other. Default is "pixel" for one image, "contour" if more than one.

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. Each channel (or group of channels; see CHAN below) is drawn on a new sub-plot. NOTE: the region specification applies equally to all the input images. Default is full image
Upto 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 to step through the image in, 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). The combination of REGION and CHAN determines how many sub-plots there will be.

In the case that you have input some combination of 2-D and 3-D images, CHAN refers to the 3-D image(s). Note that a channel is defined to be a pixel on the third axis of a cube, regardless of the cube's order (xyv or vxy say). Defaults are 1,1

Up to 3 pairs of values, one for contour image. First value is the type of contour level scale factor. "p" for percentage and "a" for absolute. Second value is the factor 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 (i.e., "a",1.0)
The levels to contour for the first specified contour image are LEVS1 times SLEV (either percentage of the image peak or absolute). Defaults try to choose something vaguely useful.
Levels for the second contour image.
Levels for the third contour image.
PGPLOT colours for LEVS1 contours. If one value is given it is used for all contours. PGPLOT colour indices are
   0: background colour (black or white)
   1: foreground colour (white or black)
   2: red           3: green           4: blue
   5: cyan          6: magenta         7: yellow
   8: orange        9: lime           10: spring green
  11: azure        12: violet         13: rose
  14: dark grey    15: light grey
Colours for the second contour image. Defaults to those for the first image.
Colours for the third contour image. Defaults to those for the first image.
Up to N groups of four values, one group per sub-plot, where N is the maximum number of channels allowed by Miriad (currently 32768). The four values are
  - MINimum image intensity to display
  - MAXimum image intensity to display
  - Transfer function type:
      lin: linear
      sqr: square root
      log: logarithmic
      heq: histogram equalization
  - Colour lookup table:
        1: b&w
        2: rainbow
        3: linear pseudo colour
        4: floating zero colour contours
        5: fixed zero colour contours
        6: rgb
        7: background
        8: heat
        9: absolute b&w
    Negate the table number to reverse the lookup table.

The transfer function changes available with OPTIONS=FIDDLE are in addition to (on top of) the selections here, but the colour lookup table selections will replace those selected here.

All subplots following the last one with a specified "range" will use the "range" settings from the previous subplot. In this way, one group of settings can be applied to all the subplots if desired. The multiple subplot capability is useful if you have used IMCAT to put unlike images into planes of a cube and you wish to display them together.

Default is linear between the image minimum and maximum with a b&w lookup table. You can default the intensity range with zeros, viz. "range=0,0,log,-2" say.

3 or 4 values. A scale factor to multiply the vector image lengths (or box image widths) by, the x and y increments (in pixels) across the image at which to plot the vectors (or boxes), and optionally the length of the scale-bar vector (unset for no scale-bar). If you have set non unit values of XYBIN, the increments here refer to the binned pixels. When VECFAC(1)=1, the vectors (boxes) are scaled so that the maximum amplitude (width) takes 1/20 of the (sub)plot size.

The scale-bar gives a graphical representation of the vector lengths, which makes vector plots easier to interpret. The scale-bar is drawn in the corner specified by the BEAMTYP key (defaulting to bottom-left if BEAMTYP is not specified). If VECFAC(4)=0, the scale bar is drawn the length of the longest vector; you can find out what this is using OPTIONS=FULL. For a fractional polarization vector map, setting VECFAC(4)=1 corresponds to 100 per cent polarization. If VECFAC(1) >> 1, this will give a very long vector. For polarization intensity images, VECFAC(4) is specified in flux density.

Defaults are 1.0, 2, VECFAC(2) Default is not to draw a scale-bar.

3 values. A scale factor to multiply the box image widths by, and the x and y increments (in pixels) across the image at which to plot the boxes). If have set non unit values of XYBIN, the increments here refer to the binned pixels. When BOXFAC(1)=1, the boxes are scaled so that there is a little bit of space between adjacent boxes. Defaults are 1.0, 2, BOXFAC(2)
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 depending on your telescope.
Up to 2 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.S (e.g. for RA)
 "dms"       the label is in D M S.S (e.g. for DEC)
 "arcsec"    the label is in arcsecond offsets
 "arcmin"    the label is in arcminute offsets
 "arcmas"    the label is in milli-arcsec 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
 "none"      no label and no numbers or ticks on the axis

All offsets are from the reference pixel. Defaults are "relpix", LABTYP(1) except if LABTYP(1)="hms" when LABTYP(2) defaults to "dms" (to give RA and DEC)

Up to 6 values. Set if you want a small polygon to be drawn to represent the beam FWHM. Setting beamtyp to "b,l" is sufficient to draw a solid beam; "b,l,4" will result in a cross-hatched beam. Use 'n' if you don't want a beam at all. The six parameters are:

- Beam vertical positioning: can be "t" (top), or "b" (bottom). No

- Beam horizontal positioning: can be "l" (left), or "r"
  (right). Default "l"

The next four parameters apply only to the first image specified with the "in" keyword. If there are multiple, different beams to draw (for example, if different uv data were used to produce images with different beam shapes), all subsequent beams are drawn as open polygons.

- Hatching style:

   1    solid (default)
   2    outline
   3    hatched
   4    cross-hatched
- Hatching angle (default 45 degrees). - Hatching line separation (default 1). - Line-width for outlines, hatching and cross-hatching (default 1)
Task enrichment options. Minimum match of all keywords is active.

"abut" means don't leave any white space between subplots. The

  default is to leave a little bit between subplots, and
  OPTIONS=GAPS leaves a lot of space and labels eacg subplot
"beamAB", where "A" is one of "b" or "t" and
                "B" is one of "l" or "r"
  means draw the beam FWHM on the plot in the corner indicated
  by the "AB" location. This option is deprecated: use the
  keyword "beamtyp" instead.
"blacklab" means that, if the device is white-background, draw
  the axis labels in black. Default is red.
"conlabel" means label the contour values on the actual
  contours.  The PGPLOT routine that does this is not very
  bright.  You will probably get too many labels.  If you bin
  the image up with keyword XYBIN, say, by a factor of 2, you
  will get about 1/2 as many labels.  If desperate use the
  overlay facility (keyword OLAY) to manually label contours.
"fiddle" means enter a routine to allow you to interactively
  change the display lookup table.  You can cycle through a
  variety of colour lookup tables, as well as alter a linear
  transfer function by the cursor location, or by selecting
  predefined transfer functions (linear, square root,
  logarithmic, histogram equalization)

  For hard copy devices (e.g. postscript), a keyboard driven
  fiddle is offered; you can cycle through different colour
  tables and invoke the predefined transfer functions, but the
  linear fiddler is not available.   Note that if you are using
  "cgdisp" from a script, so that interactive fiddling is not
  appropriate, you can use the "range" keyword to specify the
  transfer function and colour lookup tables.
"full" means do full plot annotation with contour levels, pixel
  displa range, file names, reference values, etc.  Otherwise
  more room for the plot is available.
"gaps" means leave large gaps between subplots and individually
  label the axes of each subplot. By default, the subplots will
  have a small amount of white space between each subplot and
  they will only be labelled around the borders of the full
  page.  See also OPTIONS=ABUT to eliminate the small amount of
  white space.
"grid" means draw a coordinate grid on the plot rather than just
"mirror" causes all specified contour levels for all images
  to be multiplied by -1 and added to the list of contours
"nodistort" means that angularly-defined overlays do not distort
  with the coordinate grid.  If you are displaying a large area
  of the sky, such that the non-linearities in the coordinate
  system can be seen, then by default, the overlays (keyword
  OLAY) will distort with the coordinate grid if you are using
  angular units for the overlay locations and half sizes.  Thus
  star overlays will rotate and stretch, circles will distort
  similarly.  Overlays given in non-angular units will always be
"noepoch" means don't write the epoch value into the axis labels "noerase" means don't erase a rectangle into which the "3-axis"
  values and the overlay ID strings are written.
"nofirst" means don't write the first x-axis label on any
  subplots except for the left-most one. This may avoid label
"corner" means only write labels in the lower left corner of any
"relax" means issue warnings when image axis descriptors are
  inconsistent (e.g. different pixel increments) instead
  of a fatal error.  Use at your peril.
"rot90" rotates vectors by an extra 90 degrees. Useful
  to convert E-vectors into B-vectors
"signs" Normally, when plotting vectors, CGDISP assumes that
  North is up and East to the left.  If OPTIONS=SIGNS, then
  it assumes that E and N are in the direction of increasing
  X and Y.
"single" means that when you have selected OPTIONS=FIDDLE and
  you have more than one subplot per page, activate the fiddle
  option after each subplot rather than the default, which is
  to fiddle only at the end.  In the latter case, the histogram
  equalization, if invoked, will have been computed with the
  image in the last subplot only.
"solneg1" means make negative contours solid and positive
  contours dashed for the first contour image. The default,
  and usual convention is the reverse.
"solneg2" SOLNEG1 for the second contour image. "solneg3" SOLNEG1 for the third contour image. "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
  so that the plot surface is maximally filled.  The default
  is for equal scales in x and y.
"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.
"3pixel" means label each sub-plot with the pixel value of
  the third axis.
"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).
  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 2. 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).  See also keyword
  "3format" where you can input the format for the "3value"
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.
Up to 6 values. The line widths for the axes, each contour image (in the order of TYPE), the vector image, and any overlays. If there are less than 3 contour images or no vector image, the vector image/overlay line widths shift left. Line widths must be integers. Defaults are 1,1,1,1,1,1
Up to 3 values. The intensity levels for the break between solid and dashed contours for each contour image. Defaults are 0.0,0.0,0.0
Up to 4 values. Character sizes in units of the PGPLOT default (which is ~ 1/40 of the view surface height) for the plot axis labels, the velocity/channel label, the overlay ID string (if option "write" in OLAY used) label, and the contour value labels (see options=conlab). Defaults try to choose something sensible. Use 0.0 to default any particular value. E.g., 1.4, 0, 0, 0.5
Up to 2 values. Scales in natural axis units/mm with which to plot in the x and y directions. For example, if the increments per pixel are in radians, then this number would be radians/mm (note that for RA axes you give radians on the sky per mm). Although this choice of unit may be cumbersome, it makes no assumptions about the axis type, so is more flexible. If you also chose OPTIONS=EQUAL then one of your scales, if you set both and differently, would be over-ruled. If you give only one value, the second defaults to that. Defaults choose scales to fill the page optimally. To default the first but the second, use 0.0,scale(2)
The name of a file containing a list of overlay descriptions. Wild card expansion is active and the default is no overlays.

Miriad task CGCURS OPTIONS=CURSOR,LOG,CGDISP can be used to make an overlay file.

Entries in the overlay file can be white space or comma delimitered or both. All lines beginning with # are ignored.

                **** DO NOT USE TABS ****

Double quotes " are used below to indicate a string. The " should not be put in the file. For all the string parameters discussed below, you can abbreviate them with minimum match.

Each line describes an overlay and should be as follows:

 ##### The first 5 parameters in each line must be

  1      2       3     4    5


OFIG is the type of overlay; choose from

 "sym"     pgplot symbol number (give centre, symbol, and size)
 "star"    star (i.e. cross; give centre and half-sizes)
 "box"     box (give centre and half-sizes)
 "line"    line segment (give ends)
 "vector"  directed line segment (give centre, length, and
           position angle)
 "circle"  filled in circle (give centre and radius)
 "ocircle" open circle (give centre and radius)
 "ellipse" filled-in ellipse (give centre, half axes and p.a.)
 "oellipse open ellipse (give centre, half axes and p.a.)
 "clear"   nothing, so you can write the overlay ID string (see
           below) without the overlay


 "colour"  See below.
 "lwid"    See below.
 "offset"  See below.

XOTYPE and YOTYPE give the units of the overlay location (and overlay half-sizes) contained in the file for the x- and y- directions, respectively. Choose from:

 "hms", "dms", "arcsec", "arcmin", "absdeg", "reldeg", "abspix",
 "relpix", "absnat", "relnat", "absghz", "relghz",
 "abskms", & "relkms"  as described in the keyword LABTYP.
Note that OTYPE does not depend upon what you specified for LABTYP.

ID is an identifying overlay string which can be optionally written on the overlay; it MUST be in the overlay file whether you write it on the plot or not). The ID string is written in the corner for "star" and "box", at the end for "line", and in the centre for "circle" and "clear". The underscore character "_" is treated a special case and is replaced by a blank before plotting. In this way, you can write several words as the overlay ID; you connect them with underscores in the overlay file, and cgdisp strips them out before plotting.

WRITE is "yes" or "no" to specify if the overlay ID is to be written in the overlay figure or not.

 ##### Parameters beyond number 5 depend upon OFIG, XOTYPE, and

 6   7    8   9  10  11  12  13  14  15          OFIG
 --------------------------------------   -----------------
 X   Y   SY  SS  CS  CE                   sym
 X   Y   XS  YS  CS  CE                   star, box
 X1  Y1  X2  Y2  CS  CE                   line
 X   Y   VL  PA  SS  A1  A1  A3  CS  CE   vector
 X   Y   R   CS  CE                       circle,  ocircle
 X   Y   R1  R2  PA  CS  CE               ellipse, oellipse
 X   Y   CS  CE                           clear

X,Y defines the center of the overlay in the nominated OTYPE coordinate system (X- and Y-OTYPE can be different). (X1,Y1) & (X2,Y2) are the end points of the line segment in the nominated OTYPE (mixed OTYPEs are supported here too). For %OTYPE = "abspix ", "relpix", "arcsec", "arcmin", "absdeg",

             "reldeg", "absghz", "relghz", "abskms", "relkms",
             "absnat" & "relnat" X,Y,X1,Y1,X2,Y2 are single

For %OTYPE = "hms" or "dms", the X and/or Y location is/are replaced by three numbers such as HH MM SS.S or DD MM SS.S. Thus, if XOTYPE = hms and YOTYPE = dms then the file for OFIG=box, say, should have lines like


XS, YS are the overlay half-sizes in the following units: %OTYPE = "abspix" and "relpix" in pixels

         "hms"    and "dms"    in arcseconds
         "arcsec"              in arcseconds
         "arcmin"              in arcminutes
         "absdeg" and "reldeg" in degrees
         "absghz" and "relghz" in GHz
         "abskms" and "relkms" in km/s
         "absnat" and "relnat" in natural coordinates
XS, YS are optional for OFIG="box" and "star". The defaults are XS = 2, YS = XS pixels.

CS to CE is the channel range (image planes) on which to put the overlays. If you specify only CS than the overlay is put on that channel. If CS = 0 the overlays are put on all channels. In all cases, CS and CE are optional and the default is 0 (all channels)

SY is the pgplot symbol to use for "sym".

SS is the pgplot character height to use for "sym" and "vector". May be set to zero for vectors to omit the arrowhead. Default is the character height used for overlay string.

VL is the length of the vector in pixels.

PA is the position angle in degrees, positive N -> E.

A1, A2, and A3 are the PGPLOT arrowhead style parameters: A1 is the fill-style, 1 (default) for filled or anything else

   for outline.
A2 is the acute angle of the arrow point, in degrees. Default
A3 is the fraction of the triangular arrowhead that is cut away
   from the back.  Default 0.3.

R is the radius of circle overlays in the units given in the above list according to XOTYPE only.

R1 and R2 are the ellipse major and minor axes half-widths, both in units according to XOTYPE.

##### OFIG = COLOUR (or COLOR)

A COLOUR directive can be included at any point in the overlay file in the format


where the literal "COLOUR" or "COLOR" (without the quotes) starts in column 1, followed by the PGPLOT colour index. This changes the graphics overlay colour until the next COLOUR directive is processed. PGPLOT colour indices are listed above for the cols1 parameter. The default colour index is 9.

##### OFIG = LWID

An LWID directive can be included at any point in the overlay file in the format


where the literal "LWID" (without the quotes) starts in column 1, followed by the PGPLOT line width in units of 0.005 inch (about 0.13 mm) and must be an integer in the range 1-201. This changes the graphics line width until the next LWID directive is processed. The default width is 1.


An OFFSET directive can be included at any point in the overlay file in the format


where the literal "OFFSET" (without the quotes) starts in column 1, followed by X and Y offsets which are applied to all succeeding overlay file locations.

       X = X + XOFF;   Y = Y + YOFF

These offsets must be in the same units as the %OTYPE of succeeding directives. It is intended so that your overlay locations can be in, say, arcsec relative to some location which is not the reference pixel of the image (which is what CGDISP ultimately wants). You then specify, with the OFFSET directive, the offsets between the reference pixel of the contour/pixel map images and the actual reference location of your overlay locations.

You can have as many OFFSET directive as you like in the file. All succeeding directives will apply these offsets until new ones are defined. If the directive does not appear, naturally no additional offsets are added.

The OFFSET directive is not applied to ANY position fields in succeeding directives that have %OTYPEs that are "hms" or "dms". I am too lazy to code it.

disp.for,v 1.11 2011/06/06 22:15:26 pteuben Exp $




This document was created by man2html, using the manual pages.
Time: 18:35:38 GMT, July 05, 2011