C	PROGRAM BNDCORNER.FT
C	----------------
C
C
	SUBROUTINE BNDCORNER(KX,KY,ITFLAG,AVC,AVD)
C
C	PETER LEMKIN
C	IMAGE PROCESSING UNIT, DCBD
C	NATIONAL CANCER INSTITUTE
C	NATIONAL INSTITUTES OF HEALTH
C	9000 ROCKVILLE PIKE
C	BETHESDA, MD. 20014
C
C	JULY 25, 1977
C	JULY 18, 1977
C	JULY 16, 1977
C	JULY 15, 1977
C	JULY 14, 1977
C	JULY 13, 1977
C	JULY 12, 1977
C
C	INTRODUCTION
C	------------
C	BNDCORNER COMPUTES THE CORNERITY OF THE CHAIN CODE
C	DIFFERENCES AND THEN WRITES ON (MEM,IBYTE) IF
C	THE CORNERITY IS > THE THRESHOLD.
C
C	ARGUMENTS
C	---------
C	KX (IF KX GEQ 0 THEN MEM_KX, ILSW_1 ELSE ILSE_0) - X COORDIATE
C	KY (IBYTE) - Y COORDINATE
C	ITFLAG (ICSW) - /D AND (THLOW LEQ AVD LEQ THHIGH)
C	AVC (IF > 0 THEN ENTERING DATA 
C			ELSE ENTERING DATA)
C	AVD (FIX(CORNERITY) THRESHOLD) - AVERAGE DIFFERENCE
C	OPDEFS
C	------
S	OPDEF	TADI	1400
S	OPDEF	ISZI	2400
S	OPDEF	DCAI	3400
C
C
S	OPDEF	MQA	7501
S	OPDEF	MQL	7421
S	OPDEF   KRS	6034
S	OPDEF	BSW	7002
C
C
S	OPDEF	LDXP	6443
S	OPDEF	LDYP	6444
C
S	OPDEF	DISP1	6435
S	OPDEF	DISP2	6436
C
C
C
C	[1] DETERMINE IF INIT
S	TAD I \AVC /IF IT IS < 0 THEN INIT
S	SMA CLA
S	JMP \200 /NOT INIT
	MEM=KX
S	TAD \MEM
S	SMA CLA
S	IAC /SET /L SWITCH
S	DCA \ILSW
C
	IBYTE=KY
	ICSW=ITFLAG
C
C	GET INTEGER FROM F.P ARG
	ITHCORN=0
S	TAD I \AVD
S	DCA \ITHCORN
	IXFIRST=0
	IYFIRST=0
	IXLAST=0
	IYLAST=0
	IOLD=0
	KMAX=0
	IFIRST=0
	L0AVD=-1
C
C	ZERO THE SEGMENT AVD ACCUMULATIONS
	TOTAVD=0.0
	T1AVD=0.0
	T2AVD=0.0
	EXTAVD=0.0
C
C	ZERO THE T1, T2 ANGLES ADJACENT TO EXTREMUM SEGMENT
	T1ANGLE=0.0
	T2ANGLE=0.0

C	INIT THE STATISTICS STACK
	CALL BNDCSTAT(ILSW,MEM,IBYTE,0,0,0,0,0,0,1)
C
C	ZERO THE BOUNDARY POINT INDEX COUNTER
	ICNT=0
C
C	ZERO THE CORNER NUMBER INDEX COUNTER
	KRNCNT=0
C
2047	RETURN
C
C
C	[2] ENTER POINT
C	COMPUTE CORNERITY USING CITY BLOCK DISTANCES
C	FOR T1, T2.
200	ICNT=ICNT+1
	KAVD=AVD*100.0
C	SAVE LAST AVD FOR TESTING FOR NULL T1
	L1AVD=L0AVD
	L0AVD=KAVD
C
C
C	IF ITFLAG=1
	IF(ITFLAG)210,250,210
C
C
C		THEN "ITFLAG=1: IN EXTREMUM"
C		IF IOLD=1
210	IF(IOLD)220,230,220
C
C
C			THEN 
C			BEGIN "CONTINUING ON EXTREMUM"
C			IF |KMAX| < |KAVD|
C	SAVE LAST EXTREMUM AVC IN CASE T2 IS NULL
220	SVEXTAVC=AVC
	IF(IABS(KMAX)-IABS(KAVD))221,229,229
C				THEN
C				BEGIN "FIND MAX"
C
221	KMAX=KAVD
	IXMAX=KX
	IYMAX=KY
	DMAX=AVD
C				END "FIND MAX";
C	SUM EXTREMUM AVD
229	EXTAVD=EXTAVD+AVD
	IT=IT+1
	GOTO 2047
C			END "CONTINUING ON EXTREMUM"
C
C
C	-------------------------------------------------------------
C			ELSE
C			BEGIN "START NEW EXTREMUM"
C			COMMENT COMPUTE AND TEST CORNERITY OF
C				LAST EXTREMUM IF EXITS;
230	CONTINUE
	IOLD=1
C
C			"SAVE T1"
	IT1=IT
	T1AVD=TOTAVD
	T1ANGLE=ANGLE
C
C	IF L1AVD < 0
	IF(L1AVD)231,232,232
C		THEN USE EXTREMUM STARTING POINT AVC;
231	IT1=0
	T1AVD=0
	T1ANGLE=AVC
C
C
C			"RESET COUNTERS"
232	EXTAVD=AVD
	IT=1
C
	KMAX=KAVD
	IXMAX=KX
	IYMAX=KY
C
	IXFIRST=KX
	IYFIRST=KY
C
C			RETURN
239	GOTO 2047
C			END "START NEW EXTREMUM"
C
C
C	------------------------------------------------------------
C
C
C		" ITFLAG=0: OUTSIDE OF EXTREMUM"
C		ELSE
C		IF IOLD=0 
250	CONTINUE
C
	IF(IOLD)270,251,270
C			THEN
C			BEGIN "CONTINUING BETWEEN POINTS"
C			IF (SIGN(KAVD) EQ SIGN(KOLDAVD))
S\251,	TAD \KAVD
S	SPA CLA
S	TAD (-2 /MAKE -1
S	IAC /MAKE +1
S	DCA \I
C
S	TAD \KOLDAVD
S	SPA CLA
S	TAD (-2 /MAKE -1
S	IAC /MAKE +1
S	DCA \J
C
	KOLDAVD=KAVD
C
C
	IF(I-J)260,252,260
C				THEN IT_IT+1, RETURN;
252	IT=IT+1
	TOTAVD=TOTAVD+AVD
	GOTO 2047
C
C
C				ELSE
C				BEGIN "COMPUTE CORNERITY"
C	SAVE T2
260	IT2=IT
	T2AVD=TOTAVD
	T2ANGLE=AVC
C
C	IF LT2SVKAVD <0
	IF(LT2SVKAVD)1200,1201,1201
C		THEN USE LAST EXTREMUM VALUE OF AVC;
1200	IT2=0
	T2AVD=0
	T2ANGLE=SVEXTAVC
C
C	COMPUTE CORNERITY FUNCTIONS
1201	AKMAX=KMAX
	TMAX=MAX(IT1,IT2)
	TMIN=MAX(1,MIN(IT1,IT2))
C
	CORN=AKMAX/FLOAT(MAX(IT1*IT2,1))
C
C	NOTE: ALTERNATE CORNERITY FORM!
C@	CORN=AKMAX/(TMAX+0.000001)
C
	T1C=T1AVD/FLOAT(MAX(IT1,1))
	T2C=T2AVD/FLOAT(MAX(IT2,1))
	EXC=EXTAVD/FLOAT(MAX(ITE,1))
	JPCNTCRV=EXC*100.0/(T1C+T2C+EXC+0.000001)
C
	T12SKEW=TMAX/TMIN
	TE12SKEW=TMAX/FLOAT(MAX(ITE,1))
C
C	FIND MINIMUM APERATURE WIDTH
C	CVT T2 ANGLE TO COMPLEMENT
	T2COMP=8.0-T2ANGLE
	CALL BNDHEMISPHERE(T1ANGLE,T2COMP,APC)
	APC=ABS(APC)
	CALL BNDHEMISPHERE(T1ANGLE,T2ANGLE,APA)
	APA=ABS(APA)
C
C	AP=(IF APC > APA
C			THEN APA ELSE APC);
	IF(APA-APC)265,265,264
264	AP=APC
	T2ANGLE=T2COMP
	GOTO 266
265	AP=APA
C
266	ANORMAL=T1ANGLE+(AP/2.0)
C	IF ANORMAL > 8.0
C		THEN ANORMAL=ANORMAL-8.0
	IF(ANORMAL-8.0)1262,1261,1261
1261	ANORMAL=ANORMAL-8.0
1262	CONTINUE
C
	ICORNERITY=CORN
C			IF (100 > ICORNERITY > ITHCORN)
S	TAD \ICORNERITY
S	TAD (-D100
S	SMA CLA
S	JMP \269 /NO, ICORNERITY > 100
C
	IF(ICORNERITY-ITHCORN)269,261,261
C				THEN
C				IF IFIRST=1
C					THEN WRITE(MEM,IBYTE,IXMAX,IYMAX)
C					ELSE IT_1;
261	CONTINUE
	IF(IFIRST)262,269,262
C
C	WRITE VALID CORNER.
C	IF /L 
262	KRNCNT=KRNCNT+1
	IF(ILSW)267,263,267
C
C		THEN LABEL (MEM,BYTE,IXMAX,IYMAX,255)
267	IZ=255
	CALL BMPARM(IXMAX,IYMAX,IZ,MEM,IBYTE,1)
	CALL PACK2D
	GOTO 268
C
C		ELSE WRITE DATA ON CORNER ON THE LPT:;
263	WRITE(3,2000)KRNCNT,IXMAX,IYMAX,DMAX,IT1,ITE,IT2,CORN
2000	FORMAT('0#',I2,'[',I3,':',I3,'], AVDMAX=',F5.2,', IT1=',I3
     1,', ITE=',I3,', IT2=',I3,', CORN=',F6.2)
C
	WRITE(3,2001)T1C,EXC,T2C,JPCNTCRV,T12SKEW,TE12SKEW
2001	FORMAT(' T1AVD/IT1=',F5.2,', EXTAVD/ITE=',F5.2
     1,', T2AVD/IT2=',F5.2,', %CURVE=',FI4,/
     2,' T12SKEW=',F5.2,', TE12SKEW=',F5.2)
C
	WRITE(3,2002)T1ANGLE,T2ANGLE,AP,ANORMAL
2002	FORMAT(' T1ANGLE=',F6.2,', T2ANGLE=',F6.2
     1,', APERATURE WIDTH',F6.2,' AT ', F5.2)
C
C
C
C	GO PUSH
268	CALL BNDCSTAT(IXMAX,IYMAX,T1ANG,T2ANG,ANORM,ICORN,JPCNT,ICNT
     1,AP,2)
C
C	CLEAR FIRST SWITCH
269	IFIRST=0
C
C	RESET IT (ACC. T1)
	IT=1
	TOTAVD=0.0
	ANGLE=AVC
C			RETURN;
	GOTO 2047
C				END "COMPUTE CORNERITY";
C			END "CONTINUING BETWEEN POINTS"
C
C
C	-------------------------------------------------------------
C			ELSE
C			BEGIN "END OF EXTREMUM"
270	IOLD=0
	IXLAST=KX
C	SAVE THE EXTREMUM WIDTH
	ITE=IT
C
C	SAVE FIRST AVD OF T2
	LT2SVKAVD=KAVD
	TOTAVD=AVD
C	RESET IT
	IT=1
	IYLAST=KY
	KOLDAVD=KAVD
C	SET FIRST SWITCH TO GET THE FIRST T1
C	TO COMPUTE CORNERITY
	IFIRST=1
C			RETURN;
	GOTO 2047
C			END "END OF EXTREMUM";
C	*******PARAMETERS*****
	J=0
	I=0
	END
    