1 C Copyright(c) 1997, Space Science and Engineering Center, UW-Madison
  2 C Refer to "McIDAS Software Acquisition and Distribution Policies"
  3 C in the file  mcidas/data/license.txt
  4 
  5 C *** $Id: m0grayscale.f,v 1.4 2017/07/21 00:49:29 daves Exp $ ***
  6 *$ Name:
  7 *$      m0grayscale  - Converts ALB or TEMP to BRIT (with ORIG or EXP stretch)
  8 *$
  9 *$ Interface:
 10 *$      integer function
 11 *$      m0grayscale(character option, real value, real brit)
 12 *$
 13 *$ Input:
 14 *$      option   - TEMP or ALB
 15 *$      value   - Value being converted in K (for TEMP), percent (for ALB)
 16 *$
 17 *$ Input and Output:
 18 *$      none
 19 *$
 20 *$ Output:
 21 *$      brit    - Grayscale value.
 22 *$
 23 *$ Return values:
 24 *$      function return =0 for OK
 25 *$
 26 *$ Remarks:
 27 *$      none
 28 *$
 29 *$ Categories:
 30 *$      converter
 31 *$      calibration
 32 
 33       integer function m0grayscale(option, value, brit)
 34       implicit none
 35       character*(*) option
 36       character*4 coption, cunit
 37       real brit
 38       real value
 39 
 40       integer m0brkset, m0brkval
 41       integer m0graybrkset
 42       integer istat, brkflag
 43       real tlim, con1, con2
 44       real tempk, ralb
 45       DATA CON1 /418.0/
 46       DATA CON2 /660.0/
 47       DATA TLIM /242.0/
 48       data brkflag/0/
 49 
 50       coption = option
 51 
 52 C--- CONVERT BRIGHTNESS TEMPERATURE (K) TO A GRAY SCALE
 53 
 54       if(coption .eq. 'TEMP') then
 55          tempk = value
 56          if(brkflag .eq. 0) then
 57             IF (TEMPK .LT. TLIM) THEN
 58                BRIT = CON1 - TEMPK
 59             ELSE
 60                BRIT = CON2 - 2.0 * TEMPK
 61             ENDIF
 62          else if(brkflag .eq. 1) then
 63             istat = m0brkval(tempk, brit)
 64          endif
 65 
 66          if(tempk .le. 0.0) brit = 255.0
 67 
 68          if(brit .lt.   0.0) brit = 0.0
 69          if(brit .gt. 255.0) brit = 255.0
 70 
 71          m0grayscale = 0
 72 
 73 C--- CONVERT ALBEDO (REFLECTANCE) (%) TO GRAY SCALE
 74 
 75       else if(coption .eq. 'ALB') then
 76 
 77          ralb = value
 78 
 79          if(brkflag .eq. 0) then
 80             brit = sqrt(ralb)*25.5
 81          else if(brkflag .eq. 1) then
 82             istat = m0brkval(ralb, brit)
 83          endif
 84 
 85          if(ralb .le. 0.0) brit = 0.0
 86 
 87          if(brit .lt.   0.0) brit = 0.0
 88          if(brit .gt. 255.0) brit = 255.0
 89 
 90          m0grayscale = 0
 91 
 92       else
 93          m0grayscale = -1
 94       endif
 95 
 96       RETURN
 97 
 98       entry m0graybrkset(option)
 99 
100       m0graybrkset = -1
101       istat = m0brkset(option, cunit)
102       if(istat .eq. 0) then
103          brkflag = 1
104          m0graybrkset = 0
105       endif
106 
107       return
108       end