Program Dark(Input, Output) ;
{ Reads all specified images, a strip at a time }
{ Forms a median image }
Uses
   WinAPI, { No - it's not Windows. It's BP7.0 32-bit stuff }
   X_U, { My routines for 32-bit addressing }
   FITSX_U, { Random assortment of FITS read/write stuff }
   SORT_U ; { Quicksort }
Const
  DarkName = 'C:\BP\TASS\CD5\H4RDARK.FTS' ;
{ Analysis area }
  Min2 : Integer   =    2 ;
  Max2 : Integer   = 2033 ;
  Min1 : Integer   =    6 ;
  Max1 : Integer   = 2037 ;
  NFil = 3 ;
  Name : Array[0..NFil-1] of String =
   ('D:\IDARK15.FTS',
    'D:\IDARK16.FTS',
    'D:\IDARK17.FTS') ;
Var
  F : Array[0..NFil-1] of FITSInfoT ; { FITS control structures }
  Drk : FITSInfoT ;
  FNo : Integer ; { Count files }
  I1, I2, N1_M, N2_M : Longint ;
  L : Array[0..NFil-1] of Integer ;
  Index : Array[0..NFil-1] of Integer ;
  W : Longint ;{ Width of strip }
Begin
  N2_M := Max2 - Min2 + 1 ;
  N1_M := Max1 - Min1 + 1 ;
  SetHead(Drk, N1_M, N2_M) ;
  W := 700 ; { Strip width }
  Repeat
    If (F[1].Off2 + W > Max2) Then W := Max2 - F[1].Off2 + 1 ;
    For FNo := 0 to NFil-1 Do Begin
      Writeln(FNo, '  ', F[NFil-1].Off2, '  ', W) ;
{ This is a bit Byzantine: ReadStrip and WriteStrip somehow know }
{ when they are being called for the first time on a particular  }
{ file and act accordingly. I must really get around to fixing   }
{ them so that this is made clear!                               }
      ReadStrip(F[FNo], Name[FNo], Min1, N1_M, Min2, W) ;
    End ;
    Writeln('Processing') ;
    For I2 := 0 to W-1 Do For I1 := 0 to N1_M-1 Do Begin
      For FNo := 0 to NFil-1 Do L[FNo] := IPtr(F[FNo].Image, I2*N1_M+I1)^ ;
      ISort(L, 0, NFil-1, Index) ;
      IPtr(Drk.Image, I2*N1_M+I1)^ := L[Index[(NFil-2) Div 2]] ; ;
    End ;
    Writeln('Writing from ', Drk.Off2, '  ', W) ;
    WriteStrip(Drk, DarkName, 99, N1_M, 0, W) ;
    Writeln('Written to   ', Drk.Off2) ;
  Until (Drk.Off2 >= Drk.NAxis2) ;
End. { Dark }