1 CONVERT [GREG2\]CONVERT A0 D0 [Angle] [/TYPE Ptype] [/UNIT Unit] [/SYSTEM System] [/VAR Varx Vary] This command assumes that the X,Y buffers (or the 1-D variables Varx and Vary if option /VAR is used) contain data in the specified projection (or in absolute spherical coordinates if Ptype is NONE) in the given angular unit (Degree Minute Seconds or the default Radian), in the specified System (GALACTIC or EQUATORIAL, default current system) and converts them to the current system, as defined by SET SYSTEM, and projection, as defined by command PROJECTION. Note that the projected coordinates are always natural units (i.e. the equivalent of Radians after projection). There is no provision for "hidden" parts which are treated exactly as visible ones. A0 D0 are Hours and Degrees if the input system is EQUATORIAL, Degrees otherwise. CAUTION: when using variables, the Varx and Vary arrays MUST BE REAL*8, and WRITEABLE (see HELP DEFINE). 1 ELLIPSE [GREG2\]ELLIPSE Major [Minor [Position_Angle]] [/BOX X Y] [/USER X Y [code]] [/ARC Theta_min Theta_max] [/FILL [Colour]] This command draws at current pen position (or at position (X,Y) if option /BOX or /USER is present) an ellipse of given semi-major axis, semi-minor axis, (default Minor = Major) and PositionAngle (default 0 degrees). Major, Minor, X and Y are in User Coordinates, but Position_Angle is ALWAYS in DEGREES, TRIGONOMETRIC ORIENTATION. Major, Minor, X and Y, can be 1-D arrays of any size, provided the sizes are the same. Position_Angle can be indifferently an array, a number, or omitted. The code suboption in the /USER option, if present, can be any of `SECONDS', `MINUTES', `DEGREES', `RADIANS' (in which case the X and Y coordinates are taken to be in the corresponding unit) or `ABSOLUTE' (in which case X and Y are taken as absolute coordinates, usually exprimed in sexagesimal format). The presence of the code suboption is valid only if a PROJECTION and a SYSTEM (EQUATORIAL or GALACTIC) are both defined. A portion of the ellipse can be drawn by specifying the boundary angles in option /ARC (in degrees, trigonometric sense from the position angle). Not compatible with the array mode. Option /FILL [Colour] will fill the ellipse(s), with the current or specified colour. If the /ARC option is also present, the filled area is the corresponding pie part, not the subtended arc. This command is useful for plotting beam sizes, incertainty ellipses, pie charts, etc... 1 EXTREMA [GREG2\]EXTREMA [/BLANKING Bval Eval] [/PLOT] [/COMPUTE] Computes and shows the minimum and maximum values of the Regular Grid array: shows XMIN,XMAX,YMIN,YMAX,ZMIN,ZMAX. A useful command for deciding where to set contour levels, or what size to give to the BOX if you want an exact aspect ratio between two coordinates. The current blanking value is used, but can be overridden using option /BLANKING. Option /PLOT specifies that instead of computing global extrema LOCAL extrema values should be computed, and written at appropriate places on the plot. This is a very good way to avoid ambiguities in contour map. A shortest format is used for writing the values, and the character size controls the label size. If Option /COMPUTE is not present, the extrema are only computed if not already known (from a previous call to EXTREMA, or from an image header). /COMPUTE forces computation from the data array. It should be used if for any reason the known extrema are incorrect (invalid image header, killed bad pixel, change of blanking value...). 1 GRID [GREG2\]GRID [Astep [Dstep]] [/ALTERNATE] Plots a grid of meridian and parallels according to the current projection and system. Astep is the grid step for meridian in degrees (Default 15), Dstep for Parallels (Default Rstep). If one step is 0, this part of the grid is not plotted. If the /ALTERNATE option is present, the grid will be a grid in the alternate coordinate system (Equatorial or Galactic). This does not currently work for projection type AITOFF and RADIO. 1 Language GREG2\ Language Summary CONVERT : Convert data in the X,Y buffer in the current projection. ELLIPSE : Draw an ellipse in User coordinate. EXTREMA : Shows minimum and maximum of the Regular Grid array GRID : Plot a Grid in (A,D) with steps As and Ds (in degrees) LEVELS : Sets the contour levels MASK : Mask part of a regular grid map MEAN : Computes statistics on map values PERSPECTIVE : Makes a 3-D perspective of the Regular Grid array. PLOT ; Plot a SIC image variable to the window POLYGON : Defines a polygon for use by MASK and MEAN. PROJECTION : Define a spherical projection. RANDOM_MAP : Create a Regular Grid array from randomly sampled data. RESAMPLE : Resample the Regular Grid array on a different Grid. RGDATA : Reads/Creates a 2-D map and put it in the Regular Grid array. RGMAP : Draws contour lines for the Regular Grid array STRIP : Extract a strip from the Regular Grid array WRITE : Saves an internal buffer on a file. WEDGE : Draws wedges. 2 NEWS See HELP GREG1\ News for information 1 LEVELS [GREG2\]LEVELS C1 C2 TO C3 BY C4 ... sets the contour levels to be C1, C2, C2+C4, C2+2*C4, ..C3, and so on, using the same list format as SIC\ command FOR. The contour levels are used to make contour plots of the Regular Grid array using command RGMAP. Up to 30 contours can be given at a time. Note that it is more efficient to use a single RGMAP command with many levels than many RGMAP commands with a single level each. LEVELS without arguments will display the contour levels, and LEVELS NONE reset the level list. 1 MASK [GREG2\]MASK [IN] [OUT] [/BLANKING Bval] masks all pixels of the Regular Grid array lying inside (if argument is IN) or outside (if argument is OUT or by DEFAULT) the current polygon (see command POLYGON) by attributing them a blanking value. This value is defined by command SET BLANKING, or specified using the option /BLANKING Bval. 1 MEAN [GREG2\]MEAN [/CLIP Nsigma] computes crude statistics on the part of the Regular Grid array lying inside the current polygon. Blanking values as defined in SET BLANKING are ignored. The results are displayed (some of them according to the current ANGLEUNIT), and stored in the variables POLY$SUM and POLY$AREA. If option /CLIP is present, iterative kappa sigma rejection is used to reject outlier pixels. 1 PERSPECTIVE [GREG2\]PERSPECTIVE [Altitude Azimuth] [/FACTOR Fv Ov] [/LOWER] [/LINES] [/STEP nsx nsy] [/AXES Xmin Xmax Ymin Ymax] [/CENTER] [/VERTICAL Vmin Vmax] Makes a parallel projective view of the Regular Grid array, with hidden lines removed. Altitude and Azimuth are the values of the corresponding viewing angles in Degrees. Default values are 45 and 45 at the beginning, and then the last values given. The upper part is drawn, unless the /LOWER option is present. Automatic scaling to match approximately the current box is used, but it is only a rough guess and may fail if extrema of the Regular Grid occurs near the edges. Fine tuning of the plot scale can be obtained using the /FACTOR option. It controls scaling of the Regular Grid values by the factor Fv (default 1) and an offset Ov which is in physical units along the Y direction of the plot. The Regular Grid array is plotted according to the orientation implied by command LIMITS, but the whole array is plotted. The /STEP option may be used to indicate to take only 1 pixel over Nsx ones for the X axis (resp. Nsy and Y). The /AXES option plots (X,Y) axes. The /VERTICAL option controls the max, min of plotted perpsective and plots a Z axis. The /CENTER option centers (?) the perspective. BLANKED PIXELS are forced to the minimum value of the map, or the Vmin value when the/VERTICAL option is in use. 1 PLOT [GREG2\]PLOT [Varname] [/SCALING Type Low [/BLANKING Bval Eval] [/POSITION Posx1 Posx2 Posy1 Posy2] [/LIMITS Userx1 Userx2 Usery1 Usery2] [/VISIBLE] PLOT will put a pixel image (pixels contained in the variable Varname) inside the current BOX. Varname is a 2-D SIC variable name that defaults to the RG variable if ommitted. Subsets like A[4] where A is a 3-D sic variable are not yet allowed. How to create and handle images in programs calling the GREG2\ language (including GREG) is described in the subtopic IMAGE_HOWTO. This command is normally used in the following sequence: Greg> SET BOX LOCATION Gx1 Gx2 Gy1 Gy2 ! Define box position Greg> RGDATA Varname /VARIABLE ! Put image in the RG variable, ! read associated header variables Greg> LIMITS/RGDATA ! Computes associated limits Greg> PLOT ! Plot the array in the box Greg> BOX ! Draws the box 2 /BLANKING [GREG2\]PLOT /BLANKING Bval Eval Blanking value (Bval) and tolerance (Eval). Default values are those defined by SET BLANKING command (q.v.) 2 /LIMITS [GREG2\]PLOT /LIMITS Userx1 Userx2 Usery1 Usery2 User coordinates corresponding to the image boundary. The default is those of the plotted image (when the image has any), or the current user limits if not. 2 /POSITION [GREG2\]PLOT /POSITION Posx1 Posx2 Posy1 Posy2 Box location in physical units (default is the current GreG box location) 2 /SCALING [GREG2\]PLOT /SCALING Type [Low_cut High_cut] Defines the type of transfer function to be used. Type can be LIN(EAR), LOG(ARITHMIC) of EQU(ALIZATION), and the Low_cut and High_cut are the lowest and highest represented values respectively. The default ``cuts'' are the image extrema. The current cuts are stored in variable LCUT and HCUT. The current scaling (as an integer) is stored in the variable SCALING. The LOG transfer function computes the logarithm of the pixels values, so does not like negative or null pixels. The EQUalization scaling tries its best to put the same number of pixels in each slot of the color table, thus increasing immensely the visibility of low- contrast images. This scaling mode has problem (and warns user) when a large number of pixels have exactly the same value (i.e., no contrast at all). Beware that most "real" images are obtained with receivers working with a small number (11 to 16) bits, thus restricting the range of available Real numbers in the data. The SIC variables EQUAL_NLEV and EQUAL_LEV contain the number of different levels computed in EQUALIZATION mode, and the values of these levels. Useful to know which contour levels to draw, and necessary for the WEDGE command. 2 /VISIBLE [GREG2\]PLOT /VISIBLE Specify that the image is to be always drawn, even when totally masked by an overlapping image. This allows special features like movies when typing ZOOM REFRESH. 2 IMAGE_HOWTO There exist a number of ways to get pixels into GREG2\. - Read the X, Y, Z values of a Z=f(X,Y) "image", use RGDATA (if X and Y define a regularly sampled grid) or RANDOM (if X and Y are "random points") to make a Regular Grid Map (see help GREG1\COLUMN, GREG2\RGDATA and GREG2\RANDOM) - Read a RGDATA-format file with the RGDATA command (see topic RGDATA) - Define a 2-D SIC variable and fill it with values, or connect a SIC variable with an existing GILDAS DATA FORMAT (GDF) image (See HELP SIC\DEFINE), or use the SIC\ACCEPT command to read formatted/unformatted streams of values and put them in a SIC 2-D variable (see HELP SIC\ACCEPT). Then give this 2-D variable to the internal image buffer by the RGDATA Varname/VARIABLE command. - The command GRAPHIC\IMAGE of GRAPHIC, which is a superset of GREG, connects directly an existing 2,3 or 4-D GILDA DATA FORMAT image in the GREG image buffer. Use the GRAPHIC program instead of GREG and look at HELP IMAGE. - GRAPHIC enable the parallel run of image-processing programs. Use the VECTOR\RUN FITS_GILDAS command to convert a FITS image to a GDF (Gildas Data Format) image that will be directly readable afterwards by the GRAPHIC program. - The GFITS program reads FITS images and converts them to GDF format, and the reverse. - "on-the-fly" automatic conversion from FITS to GDF format for SIC\DEFINE IMAGE and GRAPHIC\IMAGE commands. 1 POLYGON [GREG2\]POLYGON [(File)Name] [/PLOT] [/VARIABLE] [/FILL [Colour]] If no argument and no option, it calls the interactive cursor to define the polygon summits. Type any key to go to next summit, D to correct the last one and type E to end the polygon definition. The last polygon side will then appear. The polygon definition may be aborted by typing Q. For X11 displays, you may use the mouse buttons for the commands. The left mouse button draws a vertex, the middle mouse button deletes the last vertex, and the right mouse button ends the polygon definition. The drawing of the polygon is not stored in the plot, and will disappear if you refresh the plot. The polygon values are stored internally; they can be printed with the command GREG1\WRITE POLYGON, and they correspond to the variables POLY$NXY (number of vertexes), POLY$X and POLY$Y (the corresponding coordinates). The currently defined POLYGON is used by the commands MEAN and MASK. If a Name is given as argument, the cursor is not called but the summit coordinates are read from the corresponding file (X is in column 1, Y in column 2), or corresponding SIC Variable if the option /VARIABLE is also present. If you specify the option /PLOT, the current polygon will be plotted as real vectors in the plot, and no longer as temporary vectors as above. Option /FILL [Colour] will fill the current polygon, with the current or specified colour. 1 PROJECTION [GREG2\]PROJECTION [A0 D0 [Angle]] [/TYPE Ptype] Define a projection of the (celestial) sphere from point of (A0,D0), (which are Longitude and Latitude respectively) of the specified type. Angle is the angle between the Y axis and the North pole. The previous values are kept if no argument is specified. All angles are in degrees, except if the SYSTEM is EQUATORIAL in which case A0 is the right ascension and must be specified in hours. Formats like -dd:mm:ss.s or hh:mm.mmm in sexagesimal notation up to the point field are allowed. After the point, decimal values are assumed. When a projection is active, the User coordinates are assumed to be projected coordinates of the sphere, and hence in the case of small field of view where distortion are negligible, correspond to angular offsets MEASURED IN RADIANS. The field of view of the projection is defined by command LIMITS. For convenience (?), LIMITS may be specified in a so-called ANGLE_UNIT which can be set to Seconds, Minutes or Degrees. Note that only the numbers you give are assumed to be in this "ANGLE_UNIT" : they are immediately converted to the natural projected unit (equivalent to Radian in case of small field) by division by the appropriate scaling factor. That is all what this improperly named ANGLE_UNIT means. The TYPE can be - NONE Disables the projection system. User coordinates then loose their interpretation in terms of projected coordinates. The ANGLE_UNIT is then totally ignored. - GNOMONIC Radial projection on the tangent plane. Being R and P the (angular) polar coordinates from the projection point (tangent point), the projected coordinates are given by X = Tan(R).Sin(P) and Y = Tan(R).Cos(P) . - ORTHOGRAPHIC View from infinity. X = Sin(R).Sin(P) and Y = Sin(R).Cos(P) - AZIMUTHAL Spherical offsets from the projection center. X = R.Sin(P) and Y = R.Cos(P). - STEREOGRAPHIC Uses Tan(R/2) instead of Tan(R), and is thus less distorted than the Gnomonic projection. This is an inversion from the opposite pole. - LAMBERT Equal area projection. Projected distance is 2*Sin(R)/Sqrt(2*(1+Cos(R)). - AITOFF Equal area projection. Angle and D0 are ignored - RADIO The standard radio astronomy single dish mapping "projection", in which X = (A-A0).COS(D0) and Y = D-D0. The Angle is obviously ignored. 1 RANDOM_MAP [GREG2\]RANDOM_MAP [Arg1 [Arg2]] [/NEIGHBOURS Nb] [/TRIANGLES] [/EXTRAPOLATE] [/BLANKING Bval] This command is a general purpose interpolation task which uses data from the X, Y and Z arrays to fill in a Regular Grid array representing the same surface Z=f(X,Y) by an interpolation process. X, Y and Z are arrays defined by the COLUMN command (see HELP COLUMN). It triangulates the data for interpolation. If a triangulation already exists, and only the Z array has been changed, RANDOM_MAP does not make a new triangulation. Usually, the user-provided Z=f(X,Y) surface is REGULARLY SAMPLED, even if NOT COMPLETELY SAMPLED. In this case, one SHOULD USE directly the RGDATA command to create a Regular-grid map, since RANDOM is known to perform awkwardly with regularly sampled data. The interpolated grid can be defined by the arguments. If Arg1 is "RGMAP", the interpolated grid will be exactly coincident with the current Regular Grid array, else Arg1 and Arg2 are used to indicate the number of pixels in X and Y directions and Arg2 = Arg1 if not specified. Note that several hypothesis are made about the geometry of triangles in the plot page space (hence the geometry may be changed by changing the LIMIT or the BOX_LOCATION). You should thus use limits which gives a reasonable representation of what are the neighbours of a given data point. Moreover, this is an interpolation process. Hence if the basic sampling theory is not respected by your choice of input data points and output grid, spurious oscillations may occur in the resulting grid. 2 /NEIGHBOURS [GREG2\]RANDOM_MAP /NEIGHBOURS Nb The argument Nb changes the number of points influencing the interpolated values. Default is 4 and values up to 8 may be used in some cases. Caution, it slows down the program, and may enhance oscillations in some cases. 2 /TRIANGLES [GREG2\]RANDOM_MAP /TRIANGLES Plot the triangles selected by the program for interpolation. A single graphic segment will contain all triangles. 2 /EXTRAPOLATE [GREG2\]RANDOM_MAP /EXTRAPOLATE Control wether extrapolation outside the convex hull of the triangles is to be done or not. The default is not, i.e. the command fills with the blanking value the exterior of the convex hull. Beware that extrapolation is always hazardous. 2 /BLANKING [GREG2\]RANDOM_MAP /BLANKING Bval Specify the value Bval to be attributed for pixels lying outside the convex hull of triangles. The default value is that defined in the SET BLANKING command. This switch is mandatory if no default blanking value is preset and no extrapolation required. 1 RESAMPLE [GREG2\]RESAMPLE Nx Ny [/X Xref Xval Xinc] [/Y Yref Yval Yinc] [/BLANKING Bval] This command resamples (by bilinear interpolation) the current regular grid array on a different grid. The number of pixels of the new grid must be specified. Unless the user specifies an explicit conversion formula in the /X and /Y options, the program adjusts it to match the current Regular Grid array. A blanking value MUST BE specified (either by default in SET BLANKING or using the option /BLANKING) because no extrapolation is performed. For the same reason, any output pixel's value that would be interpolated from at least one input blanked pixel, is itself blanked. 1 RGDATA [GREG2\]RGDATA [Name|Array_X Array_Y Array_Z] [/SUBSET NXmin NYmin NXmax NYmax] [/VARIABLE] [/FORMAT Fmt [code]] [/INCREMENT IncX IncY] [/BLANKING Bval] This command optionally creates, then loads a two-dimensional map into the Regular Grid array (to be contoured by RGMAP, plotted by PLOT...). This is THE basic command needed for subsequent 2-dimensional treatment. "Regular Grid" means that data is internally stored as a two-dimensional array, thus lies on a Regularly sampled Grid. The user-provided "pixel values" may come from various "descriptions" of such regularly sampled (but possibly uncompletely sampled) data: 1) Three 1-dimensional arrays, say, X Y and Z, that contain Z=f(X,Y) at regular intervals in X and Y. 2) A preexisting internal 2-D array (possibly a section of a 3D or 4D array). 3) An external, specially formatted, file. For data NOT REGULARLY ("randomly") sampled, use the GREG2\RANDOM_MAP command instead. The Regular Grid is itself a 2D SIC variable under the name "RG". Once loaded, the RG can be saved on a file with the command GREG2\WRITE. The following command syntax is used to deduce which "description" is provided: - Without arguments following the command, or with 3 arguments, RGDATA will try to assemble Z=f(X,Y) either form the X,Y and Z arrays (as defined by command COLUMN) or from "Array_X Array_Y Array_Z", that should be 1D SIC variables previously created by command SIC\DEFINE. The option /INCREMENT is used to force the X and Y sampling interval to (IncX,IncY) in case of roundoff errors. If a blanking value is currently defined, non-sampled pixels will be attributed this value, which is overriden by the Bval value of the /BLANKING option. Note that, if a blanking value is currently defined, pixels for which X or Y are in the blanking range are themselves blanked. - With ONE argument (Name) following the command, Name is taken as the name of an existing SIC 2D variable if option /VARIABLE is present. Otherwise, Name is a specially formatted file (see HELP RGDATA FILE_FORMAT) from which the Regular Grid array must be read in. A rectangular SUBSET of the array, defined by the pixel coordinates of the Bottom Left Corner and Top Right Corner can be selected. RGDATA allocates virtual memory according to the map size, so that there is no limit on the array dimensions. Beware however that handling maps larger than 512 by 512 pixels may be slow... 2 /FORMAT The /FORMAT option governs how the data part (pixel values) of the RGDATA file must be read by GreG. fmt is a valid fortran format (default is 10z8, the minimal way to encode real*4 data). code may be BY , R4 , R8 , I4 , I2, depending if the data written in the file are BYtes, Real4, Real8, Integer4 or Integer2. (the values in the GreG map will always be Reals*4 after the read is done). 2 FILE_FORMAT The format for the input file consits of a four line header as such: 1st line : NX XREF XVAL XINC 2nd line : (any comment for first axis, could be blank) 3rd line : NY YREF YVAL YINC 4th line : (any comment for 2nd axis, could be blank) followed by the data (NX times NY pixel values) in a format which can be specified with the /FORMAT option when the default 10z8 is not used. NX is the number of pixels in the 1st dimension of the map (on the "X axis"), XREF the index of the pixel for which the actual X abscissa value is XVAL, the increment between two pixels being XINC, and the same for the y axis. Thus, the abcissa X of the pixel 'I' is just X=(I- XREF)*XINC+XVAL This format is very simple-minded (so that any inexperienced programmer can use it in less than 5 minutes), but highly non efficient in I/O processing. A more elaborate data format ("IMAGES"), specially suited for astronomical applications and large maps is available in the GRAPHIC program (a superset of GreG), or directly using SIC variables (command SIC\DEFINE) and the /VARIABLE option of this command. One should read once its data in RGDATA format in GreG, then convert it for future use in IMAGE format with the command GREG2\WRITE IMAGE filename. See also the IMAGE_HOWTO subtopic of the GREG2\PLOT command. 1 RGMAP [GREG2\]RGMAP [Quiet|Fast|chunksize] [/PERCENT P1] [/ABSOLUTE A1] [/BLANKING Bval Eval] [/GREY COLOUR N] [/KEEP File_Name [Blank]] Draws (or Fills) isocontours of the Regular Grid array. The RG is an internal 2D "map" created/loaded by various commands (RGDATA, RANDOM_MAP, RESAMPLE, IMAGE), or loaded by a calling program. The levels are those specified by command LEVELS, but may be affected by a scaling factor by option /PERCENT or /ABSOLUTE. This command is normally used in the following sequence: Greg> SET BOX LOCATION Gx1 Gx2 Gy1 Gy2 ! Define box position Greg> RGDATA (options...) ! Put image in the RG variable, ! read associated header variables Greg> LIMITS/RGDATA ! Computes associated limits Greg> PLOT ! Plot the array in the box Greg> BOX ! Draws the box Greg> LEVELS 0.1 to 0.9 by 0.1 ! define contour levels Greg> RGMAP/PERCENT 1 ! Draw contour levels (in this ! case, as percentage of peak) The "Quiet" mode does contouring silently. For "Fast" and "chunksize" modifiers, see subtopic MEMORY_OPTIONS 2 MEMORY_OPTIONS The program normally allocates less that 1/5 of the total number of pixels in the map to store the contour segments, and warns the user when that limit is reached. Besides, contouring may be slow on large maps. The modifier "Fast" cuts the map in smaller "chunks" and performs contouring on those submaps, without the 1/5 above limitation. The Contour-filling mode (/GREY) can consume (temporary) a large amount of memory, so is always performed on subsets of the image ("chunks") when the image size is greater than a system-dependent limit (256*256 on UNIX systems). When the contours are too involved, an internal limit can nevertheless be reached. One can then retry the contour-filling by specifying a smaller "Chunksize" (in pixels). For example, to force contour-filling on subsets of 64 "lines" of a 512x512 pixel image, type RGMAP 64*512 /GREY 2 /PERCENT [GREG2\]RGMAP /PERCENT P1 Computes M=MAX(ABS(min),ABS(max)) of the data to be contoured. Contour levels selected with LEVELS are multiples of P1 percent of M. E.g. if P1 = 10 and LEVELS 1 2 5 9, the contour levels are 10, 20, 50 and 90% of the peak value. 2 /ABSOLUTE [GREG2\]RGMAP /ABSOLUTE A1 Contour levels are multiples of A1, e.g. for LEVELS 1 2 3, the contour used will be A1 2*A1 3*A1. 2 /BLANKING [GREG2\]RGMAP /BLANKING Bval Eval Override the current blanking value as defined by command SET BLANKING. Contours are not drawn in pixels touching pixels with value V so that ABS(V-Bval) <= Eval . This is extremely useful for regular grids only partially filled as often occur in astronomy. 2 /GREY [GREG2\]RGMAP /GREY [start [step] [background]] On graphic displays with area filling capabilities, fills contours with up to 16 different color pens (but the number of contours is not limited to 16). These pen colors may be changed in the same manner as for the pixels colors (see HELP LUT /PEN). "start" (default 0) and "step" (default 1) may be used to change the exploration of the 16-pen palette. "background" is the number of a color used to fill the map before contour-filling, thus providing a user-defined background for the contour-filled map. In case of Filling problems, see the subtopic MEMORY_OPTIONS of this HELP. 2 /KEEP [GREG2\]RGMAP /KEEP File_Name [Blank] Will keep a formatted copy of the coordinates of the contour points in the specified file. This file can later be used as an input file for COLUMN. X coordinates are in column 1 and Y coordinates in column 2. The Blank value is written as a separator value for later CONNECT/BLANKING Blank. Blank defaults to the SET BLANKING value if it exists, else Blank is mandatory. 2 /PENS [GREG2\]RGMAP /PENS [Pos Neg] Selects the pens for positive and negative contours. Three modes of operation are possible : - Without option /PENS, positive contour levels use pen 0 and negative contour levels use pen 15. Positive means that the value given in command LEVELS is positive, not the final contour level value which is affected by a possibly negative factor. - With option /PENS, all contours use the current pen. - With /PENS Pos Neg, positive contours use pen number Pos and negative contours use pen number Neg. 1 STRIP [GREG2\]STRIP [X1 Y1 X2 Y2] Will extract from the current Regular Grid array a strip going through points (X1,Y1) and (X2,Y2) in User coordinates. If no arguments are present, it will call the cursor to set the two points. Although the end points need not be on the map boundaries, STRIP will always produce a full strip across the map. For strip parallel to the X or Y map axis, the nearest pixel is used to fill the values. For any other strip orientation, if the tangent of the angle is less than (NY-1)/(NX-1) (i.e. if you scan the X map axis faster than the Y map axis), the number of resulting points on the strip profile will be NX and the user coordinates along the strip will be the map X coordinate. For each pixel, interpolation along the Y axis is done using the three nearby Y pixels. A similar situation with X replacing Y occurs if the angle is larger. The map user coordinates are put into the X buffer, and map values into the Y buffer. The strip can then be plotted using CONNECT, but remember to set decent limits before. 1 WEDGE [GREG2\]WEDGE [Top|Bottom|Left|Right [Size]] [/SCALING Lin|Log|Equ Min Max] [/LEVEL [Label] ] Will plot a WEDGE along the current BOX. WEDGES are used after a PLOT command to show the relationship between pixel hues and image values. The default position is Right, i.e., on the right side of the box, but the other location and size modifiers are self-explanatory. The SCALING defaults to the current scaling of the last image PLOTted, but can be changed (as in command PLOT) with the /SCALING option. The /LEVEL option will draw levels (as defined by the LEVEL command) at their appropriate location on the wedge. The modifier Label will label the wedge axis with the level values. This is the default (i.e., some levels should be defined) for the EQUALIZATION Mode, for which the relationship between pixel hues and image values is strongly non-linear. 1 WRITE [GREG2\]WRITE Item File_Name [/TABLE [X Nx] [Y Ny] [Z Nz]] This command is used to saves some GreG internal buffers on an output file for later processing. The item specify what is to be saved, and the format of saving, and can be : - POLYGON Saves the current polygon in formatted way on two columns easily readable by command COLUMN or POLYGON later. The default extension is .POL. - RGDATA Saves the current Regular Grid array on a RGDATA-like output file (to preserve the result of a masking, or of a random mapping interpolation). The default extension is .DAT. - IMAGE Same as above but uses the more efficient and complete IMAGE data format of GILDAS. The default extension is .GDF. - COLUMN Saves the current X Y Z buffers on a formatted output file (after a SORT or a STRIP for example). The default extension is .DAT. [GREG2\]WRITE COLUMN File_Name [NEW]/TABLE [X Nx] [Y Ny] [Z Nz] also saves the X Y Z buffers but on column Nx,Ny,Nz of the specified output table (GILDAS format). A new table is created if argument NEW is specified, otherwise the table must already exists. The table may be expanded if any of Nx,Ny or Nz exceed the table column number ; exact match on the number of lines is required. The tables can be read by command COLUMN/TABLE. 1 END