3.3 Using bitmaps

The command controlling the appearance of a 2D plot is 'hart'. Its first parameter determines the data set, the second parameter the type of plot. To use only contour lines set the second parameter to '1', for bitmap display use '2' and to have both a bitmap and contour lines set the second parameter of the 'hart' command to '3'. In Figure 3.3 we can see the same plot using just a bitmap on the bottom and using additional contour lines on the top. The wedge $\star$]$\star$ showing the z range of the bitmap colours is activated by setting a label for the z-axis using the command 'achz'.

  

Figure 3.3: Example for bitmap plots

The bitmaps used by KUPLOT have 240 colour entries, the remaining 16 colours are reserved for other functions. The z-range to be converted to those 240 colours is determined by the minimal and maximal contour level for the first set defined by the command 'hlin'. Subsequently the bitmap colour range and the contour levels are the same for the first set of contour levels. In some cases one might want to create a plot where the bitmap and the contour lines have different ranges. This can be done like in the following example:

    hlin 1,0,50,1,%
    hlin 2,0,5,20,%
    htyp 1,0
    htyp 2,1

The levels set by the first 'hlin' command determine the z-range used to create the bitmap, i.e. 0% to 50% of the z-range. We do this in a single step since only the maxima are used to determine the bitmap. The second 'hlin' command sets the contour lines we actually want to plot on top of the bitmap. In order to suppress the first set of contour lines we set the line type for set 1 to '0', i.e. no line using the first 'htyp' command. The line type for the second contour set is set to '1', i.e. solid line, as done in the last line of the example above.

KUPLOT has three default colour maps used to display bitmaps. The map is selected by the command 'cmap'. For a description of the different colour maps refer to the online help. The selected map for the examples displayed in Figure 3.3 is 'gray'. The command 'cmap' is also used to save or read a colour map from a file. Additionally the current colour map can be altered using the variable cmap. For details about the usage of variables see section 6.1 of this users guide.