C
C $$ PW2SDR.FOR
C
C **********************************************************************
C=* FROM: SPIDER - MODULAR IMAGE PROCESSING SYSTEM.   AUTHOR: J.FRANK  *
C=* Copyright (C) 1985-2005  Health Research Inc.                      *
C=*                                                                    *
C=* HEALTH RESEARCH INCORPORATED (HRI),                                *   
C=* ONE UNIVERSITY PLACE, RENSSELAER, NY 12144-3455.                   *
C=*                                                                    *
C=* Email:  spider@wadsworth.org                                       *
C=*                                                                    *
C=* This program is free software; you can redistribute it and/or      *
C=* modify it under the terms of the GNU General Public License as     *
C=* published by the Free Software Foundation; either version 2 of the *
C=* License, or (at your option) any later version.                    *
C=*                                                                    *
C=* This program is distributed in the hope that it will be useful,    *
C=* but WITHOUT ANY WARRANTY; without even the implied warranty of     *
C=* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU  *
C=* General Public License for more details.                           *
C=*                                                                    *
C=* You should have received a copy of the GNU General Public License  *
C=* along with this program; if not, write to the                      *
C=* Free Software Foundation, Inc.,                                    *
C=* 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.      *
C=*                                                                    *
C **********************************************************************
C
C
C
C IMAGE_PROCESSING_ROUTINE
C
C        1         2         3         4         5         6         7
C23456789012345678901234567890123456789012345678901234567890123456789012
C--*********************************************************************
C
C $$ PW2SDR.FOR
C
        SUBROUTINE  PW2SDR(LUN1,LUN2,NSAM,NROW,MODE)
        DIMENSION   Q(NSAM+2-MOD(NSAM,2)),T(NSAM)
        CHARACTER*1  MODE
        LOGICAL*1 IFND

        NNNN = NSAM+2-MOD(NSAM,2)
        IFND=MOD(NROW,2).EQ.0
        NSC=NSAM/2+1

        DO    J=1,NROW
           CALL  REDLIN(LUN1,Q,NNNN,J)

C  Reaplce F(0,0) for visualization
	IF(J.EQ.1)  THEN
	  Q(1)=Q(3)
	  Q(2)=Q(4)
	ENDIF
C
           SCL=2.0/FLOAT(NSAM)/FLOAT(NROW)
        IF(MODE.EQ.'2')  THEN
           DO    I=NNNN-1,1,-2
              Q(NNNN-1-(NNNN-1-I)/2)=
     &          SCL*SCL*(Q(I+1)*Q(I+1)+Q(I)*Q(I))
           ENDDO
        ELSE
           DO    I=NNNN-1,1,-2
              Q(NNNN-1-(NNNN-1-I)/2)=
     &          SCL*SQRT(Q(I+1)*Q(I+1)+Q(I)*Q(I))
           ENDDO
        ENDIF
           IF(MODE.EQ.'L')  CALL  AL10(Q(NSAM/2),NSAM/2)
C          HAVE TO MOVE THE LAST ELEMENT
           Q(1)=Q(NNNN-1)
           CALL  WRTLIN(LUN2,Q,NSAM,J)
        ENDDO
C       CLOSE(LUN1)

        DO    J=1,NROW/2
           JJ=J+NROW/2+MOD(NROW,2)
           CALL  REDLIN(LUN2,Q,NSAM,J)
           CALL  REDLIN(LUN2,T,NSAM,JJ)
           CALL  WRTLIN(LUN2,Q,NSAM,JJ)
           CALL  WRTLIN(LUN2,T,NSAM,J)
        ENDDO

        IF(.NOT.IFND)  THEN
           CALL  REDLIN(LUN2,T,NSAM,NROW/2+1)
           DO    J=NROW/2+1,NROW-1
              CALL  REDLIN(LUN2,Q,NSAM,J+1)
              CALL  WRTLIN(LUN2,Q,NSAM,J)
           ENDDO
           CALL  WRTLIN(LUN2,T,NSAM,NROW)
        ENDIF   

        NSC=NNNN/2-1
        IF(IFND)  THEN
           JB=2
           CALL  REDLIN(LUN2,Q,NSAM,1)
           DO    I=2,NSC
              II=NNNN-I
              Q(I)=Q(II)
           ENDDO
           CALL  WRTLIN(LUN2,Q,NSAM,1)
        ELSE
           JB=1
        ENDIF
        DO    J=JB,NROW
           JJ=NROW-J+JB
           CALL  REDLIN(LUN2,Q,NSAM,J)
           CALL  REDLIN(LUN2,T,NSAM,JJ)
           Q(1)=T(1)
           DO    I=2,NSC
              II=NNNN-I
              Q(I)=T(II)
           ENDDO
           CALL  WRTLIN(LUN2,Q,NSAM,J)
        ENDDO
C
         END