PCTREAD -- Read PCT from Text File


<HEAD><TITLE>PCTREAD -- Read PCT from Text File</TITLE></HEAD>


<H1>PCTREAD -- Read PCT from Text File</H1>
Reads a pseudocolour table from a text file, then transfers the data
to the pseudocolour table segment on a database file.
<P>

See Also: <A HREF = "http://www.pcigeomatics.com/cgi-bin/pcihlp/PCTWRIT">PCTWRIT</A><P>
<H3>PARAMETERS</H3>
PCTREAD is controlled by the following global parameters:
<P>
<pre>Name     Prompt                                  Count     Type
FILE     Database File Name                      1-64      Char
DBPCT    Database Pseudocolour Segment           0-1       Int
DBSN     Database Segment Name                   1-8       Char
DBSD     Database Segment Description            0-64      Char
PCTFORM  PCT Text Form: ATT/INOUT/OUT            3-5       Char
TFILE    Text File                               1-64      Char

The following parameter receives output:

LASC     Last Segment Created                    0-1       Int
</pre>
<H4>FILE</H4>
Specifies the name of the PCIDSK image file.
<P>
<PRE>
 EASI&gt;FILE=&quot;filespec&quot;
</PRE>
<H4>DBPCT</H4>
Specifies the database segment that contains the pseudocolour table
(type 171).
<P>
<PRE>
 EASI&gt;DBPCT=i
</PRE>
If DBPCT is unspecified, a new pseudocolour table segment is
created.
<P>
<H4>TFILE</H4>
<PRE>
  Valid Values:   &lt;filename, max. 64 characters&gt;
  Default:        &lt;none&gt;
</PRE>
Specifies the name of the input text file, from which the
pseudocolour table data are read.
<P>
<H4>DBSN</H4>
<PRE>
  Valid Values:   &lt;string, max. 8 characters&gt;
  Default:        PCTREAD
</PRE>
Specifies an identifier that is assigned to the output pseudocolour
table segment. This string is displayed by ASL, and may be changed
with the MAS program.<p>
DBSN is only required if a new segment is created.
<P>
<H4>DBSD</H4>
<PRE>
  Valid Values:   &lt;string, max. 64 characters&gt;
  Default:        &lt;none&gt;
</PRE>
Optionally specifies a descriptor that is associated with the output
segment (string describing contents or origin of data).<p>
This string is displayed by ASL if LTYP = &quot;SHORT&quot; or &quot;FULL&quot;, and
may be changed with MAS.<p>
DBSD may only be used if a new segment is created.
<P>
<H4>PCTFORM</H4>
<PRE>
  Valid Values:   ATT, INOUT, OUT
  Default:        ATT
</PRE>
Specifies the format for the pseudocolour table data in the text
file.
<P>
<PRE>
 ATT            | Attribute format      (range r g b)
 INOUT          | Input/Output format   (level r g b
 OUT            | Output format         (r g b)
</PRE>
<H4>LASC</H4>
If a new segment is created, then LASC is assigned the number for
the new segment, after PCTREAD finishes executing.
<P>
<H3>DETAILS</H3>
PCTREAD transfers pseudocolour table data from a specified text file
(TFILE) to a pseudocolour table segment (DBPCT) on a database
(FILE), assuming a given text file format (PCTFORM).<p>
There are three formats (PCTFORM) available:
<P>
<UL>
<LI> Attribute format (PCTFORM= &quot;ATT&quot;) uses PCI's attribute data
format for storing pseudocolour table. See the Attribute Data
chapter in the `Using PCI Software' manual for details on the
attribute data format. The general form for a line of text is as
follows: 
</UL>
<PRE>
               start : end ; red green blue ; comment

     example:      5 :   5 ; 255     0  255 ; magenta
</PRE>
<UL>
<LI> Input/output format (PCTFORM=&quot;INOUT&quot;) list both an input value
and three output values (red, green, and blue) for each table
entry. The general form for a line of text is as follows: 
</UL>
<PRE>
                 input   red green  blue

     example:      5     255     0   255
</PRE>
<UL>
<LI> Output format (PCTFORM=&quot;OUT&quot;) lists only the three output
values (red, green, and blue) for each table entry. The general
form for a line of text is as follows: 
</UL>
<PRE>
                 red green  blue

     example:    255     0   255
</PRE>
Note: It is not essential that all 256 entries in a pseudocolour
table be specified in the text file. If a new segment is created,
the output values for any missing entries default to 0. If an
existing segment was specified, only the table entries which are
read in are modified.
<P>
<H3>EXAMPLE</H3>
Read a pseudocolour table from the text file classpct.txt, which
stores a pseudocolour table in attribute format. This table can be
used to display the results of a multispectral classification, where
eight classes are assigned different colours. The text file is shown
below:
<P>
<PRE>
 ! Pseudocolour table for showing results of classification.
 !
 ! min : max  ;   red green  blue  ; comments
 !
          0  ;     0     0     0  ; null class (black)
          1  ;   255     0     0  ; class 1 (red)
          2  ;     0   255     0  ; class 2 (green)
          3  ;     0     0   255  ; class 3 (blue)
          4  ;     255 255     0  ; class 4 (yellow)
          5  ;     0   255   255  ; class 5 (cyan)
          6  ;   255     0   255  ; class 6 (magenta)
          7  ;   128   128   128  ; class 7 (grey)
          8  ;   255   128    64  ; class 8 (orange)
    9 : 255  ;   255   255   255  ; all other (white)
</PRE>
Read the text file into a new pseudocolour table segment, checking
for the attribute data format.
<P>
<PRE>
 EASI&gt;FILE=&quot;local.pix&quot;
 EASI&gt;DBPCT=
 EASI&gt;PCTFORM=&quot;ATT&quot;
 EASI&gt;DBSN=&quot;CLASSPCT&quot;
 EASI&gt;DBSD=&quot;PCT for showing results of 8-class classification&quot;
 EASI&gt;TFILE=&quot;classpct.txt&quot;
 EASI&gt;RUN PCTREAD
</PRE>
Run PCTREP to verify that the pseudocolour table was read in.
<P>
<PRE>
 EASI&gt;DBPCT=LASC
 EASI&gt;REPORT=
 EASI&gt;RUN PCTREP
</PRE>
PCTREP Pseudocolour Table Report V5.3 EASI/PACE 14:47 11-JUN-90<p>
6:CLASSPCT Type:171 [Pseudocolour] Last Update: 14:46 11-JUN-90
Contents: PCT for showing results of 8-class classification
<P>
<PRE>
             0               1               2               3
     +---------------------------------------------------------------
   0 |   0r   0g   0b  255r   0g   0b    0r 255g   0b    0r   0g 255b
   4 | 255r 255g   0b    0r 255g 255b  255r   0g 255b  128r 128g 128b
   8 | 255r 128g  64b  255r 255g 255b  255r 255g 255b  255r 255g 255b
  12 | 255r 255g 255b  255r 255g 255b  255r 255g 255b  255r 255g 255b
  16 | 255r 255g 255b  255r 255g 255b  255r 255g 255b  255r 255g 255b
  24 | 255r 255g 255b  255r 255g 255b  255r 255g 255b  255r 255g 255b
 .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
 252 | 255r 255g 255b  255r 255g 255b  255r 255g 255b  255r 255g 255b
</PRE>
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