PCTINT

Description

PCTINT interpolates between non-zero colors in a pseudocolor table (PCT).

Parameters

pctint(file, dbpct)

Name	Type	Caption	Length	Value range
FILE *	str	Input file name	1 -
DBPCT *	List[int]	Pseudocolor table segment	1 - 1

* Required parameter

Parameter descriptions

FILE

Specifies the name of the PCIDSK image file containing the input pseudocolor table segment.

DBPCT

Specifies the pseudocolor table segment (type 121) that holds the pseudocolor table to be interpolated.

Details

PCTINT is used to interpolate non-zero color ranges in a pseudocolor table PCT segment between pre-initialized color values. All values to be interpolated should be black (0,0,0) before running PCTINT.

A typical use of PCTINT is to interpolate colors between known codings. For instance, specific colors might be attached to elevations of 10, 20, 30, and 40 meters, but with PCTINT it is possible to show gradual changes between these values.

A simple linear interpolation scheme is used to compute the new value of (0,0,0) PCT entries based on the previous and next non- zero color entry. If there are no previous and next colors, the (0,0,0) entries will not be replaced. Thus a range of zeros at the beginning or end of the table will remain zero.

Although pure black (0,0,0) values may not be used as a real color, it is possible to use near black (0,0,1) or (1,1,1) instead.

Example

The following example reads a text file (rgb.txt) containing three color values to interpolate among, and then runs PCTINT to fill in all the missing (0,0,0) values.

The text file (rgb.txt) contains the following:

 rgb.txt:
   0 100   0 255
 100 100 120  50
 255 255 255 255

from pci.pctint import pctint
from pci.pctread import pctread

file='irvine.pix'
dbpct=[]
dbsn='Smooth'
dbsd=''
pctform='INOUT'
tfile='rgb.txt'
lasc=pctread(file, dbpct, dbsn, dbsd, pctform, tfile)


dbpct = [lasc]            # Use segment created by PCTREAD
pctint (file,dbpct)

      Input PCT:        Output PCT:
   0: 100   0 255       100   0 255
   1:   0   0   0       100   1 253
   2:   0   0   0       100   2 251
   3:   0   0   0       100   4 249
          ...               ...
  98:   0   0   0       100 118  54
  99:   0   0   0       100 119  52
 100: 100 120  50       100 120  50
 101:   0   0   0       101 120  51
 102:   0   0   0       102 128  53
 103:   0   0   0       103 120  54
          ...               ...
 253:   0   0   0       253 120 252
 254:   0   0   0       254 120 254
 255: 255 120 255       255 120 255

Environments	PYTHON :: EASI :: MODELER
Quick links	Description :: Parameters :: Parameter descriptions :: Details :: Example :: Related