The two stages may be repeated cyclically if desired. To exit the loop give the
!, to a prompt. Looping will not occur if the lookup table and
the distribution method are supplied on the command line.
[Current graphics device
"Negative"–- This is negative grey scale with black assigned to the highest pen, and white assigned to the lowest available pen.
"Colour"–- This consists of eighteen standard colour blocks.
"Grey"–- This a standard grey scale.
"External"–- Obtain a lookup table stored in an NDF’s data array. If the table cannot be found in the specified NDF or if it is not a LUT then a grey scale is used.
FULL = _LOGICAL (Read)
TRUEthe whole colour-table for the device is stored including the reserved pens. This is necessary to save a colour table written by another package that does not reserve colour indices. For colour tables produced by Kappa this should be
"Histogram"–- The colours are fitted to the pens using histogram equalisation of an NDF, given by Parameter IN, so that the colours approximately have an even distribution. In other words each pen is used approximately an equal number of times to display the two-dimensional NDF array. There must be an existing graphics deviceed. This is determined by looking for a DATA picture in the database. This is not foolproof as this may be a line plot rather an image.
"Linear"–- The colours are fitted directly to the pens.
"Logarithmic"–- The colours are fitted logarithmically to the pens, with colour 1 given to the first available pen and colour NINTS given to the last pen.
NDF = NDF (Read)
TRUEthe input lookup table is mapped to the colour table by using the nearest-neighbour method. This preserves sharp edges and is better for lookup tables with blocks of colour. If NN is
FALSElinear interpolation is used, and this is suitable for smoothly varying colour tables.
[25,75]would scale between the quartile values. It is advisable not to choose the limits less than 3 per cent and greater than 97. The percentiles are only required for histogram mapping. All values in the NDF’s data array less than the value corresponding to the lower percentile will have the colour of the first unreserved pen. All values greater than the value corresponding to the upper percentile will have the colour of the last unreserved pen.
1emphasises low values;
1emphasises high values;
0is neutral, all values have equal weight. The shade must lie in the range 1 to 1.
The effects of this command will only be immediately apparent when run on X windows which have 256 colours (or other similar pseudocolour devices). On other devices (for instance, X windows with more than 256 colours) the effects will only become apparent when subsequent graphics applications are run.