From 065b523c45b707e7b4f49a9d976f901f8a6e9061 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ian@liberator.relativity.greenend.org.uk>
Date: Sat, 4 Jul 2009 19:35:56 +0100
Subject: [PATCH] Correct range brackets for antialias to integer graymap
 conversion

---
 pctb/Makefile    |  2 +-
 pctb/common.h    |  1 +
 pctb/structure.c | 21 +++++++++++++++------
 3 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/pctb/Makefile b/pctb/Makefile
index d99bb25..6ebc48d 100644
--- a/pctb/Makefile
+++ b/pctb/Makefile
@@ -37,7 +37,7 @@ all: $(TARGETS)
 
 CONVERT_OBJS= convert.o ocr.o pages.o structure.o common.o rgbimage.o resolve.o
 
-ypp-commodities: $(CONVERT_OBJS) -lnetpbm -lXtst -lX11 -lpcre
+ypp-commodities: $(CONVERT_OBJS) -lnetpbm -lXtst -lX11 -lpcre -lm
 	$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $^ $(LDLIBS)
 
 $(CONVERT_OBJS): ocr.h convert.h structure.h common.h
diff --git a/pctb/common.h b/pctb/common.h
index d4464bd..fe87e16 100644
--- a/pctb/common.h
+++ b/pctb/common.h
@@ -32,6 +32,7 @@
 
 #include <locale.h>
 #include <stdarg.h>
+#include <math.h>
 #include <stdio.h>
 #include <errno.h>
 #include <assert.h>
diff --git a/pctb/structure.c b/pctb/structure.c
index 2bb6429..200b86e 100644
--- a/pctb/structure.c
+++ b/pctb/structure.c
@@ -484,7 +484,15 @@ static void find_table_entry(Rect commod, int colno, Rect *cell) {
 	 colno, cell->tl.x,cell->tl.y, cell->br.x,cell->br.y,
 	 bg_count, light_count, dark_count);
   
-  Rgb foreground= light_count ? 0xffffffU : 0;
+  Rgb foreground;
+  double fg_extra;
+  if (light_count) {
+    foreground= 0xffffffU;
+    fg_extra= +1;
+  } else {
+    foreground= 0;
+    fg_extra= -1;
+  }
   int monochrome= 1;
 
   FOR_P_RECT(p,*cell) {
@@ -496,8 +504,8 @@ static void find_table_entry(Rect commod, int colno, Rect *cell) {
       unsigned char bg_chan=   background >> (i*8);
       unsigned char fg_chan=   foreground >> (i*8);
       double alpha_chan=
-	((double)here_chan - (double)bg_chan) /
-	((double)fg_chan   - (double)bg_chan);
+	((double)here_chan    - (double)bg_chan) /
+	((fg_chan + fg_extra) - (double)bg_chan);
       alpha[i]= alpha_chan;
       alpha_mean += alpha_chan * (1/3.0);
     }
@@ -510,10 +518,11 @@ static void find_table_entry(Rect commod, int colno, Rect *cell) {
 	    MI(i);MRGB(here);MRGB(background);MRGB(foreground);
 	    MF(alpha_min);MF(alpha[i]);MF(alpha_max) );
 
-    MUST( 0 <= alpha_mean && alpha_mean <= 1,
+    MUST( 0 <= alpha_mean && alpha_mean < 0.999,
 	  MRGB(here);MRGB(background);MRGB(foreground);
-	  MF(alpha_mean) );
-    int here_int= AAMAXVAL*alpha_mean;
+	  MF(alpha_mean); MF(alpha[0]);MF(alpha[1]);MF(alpha[2]); );
+    int here_int= floor((AAMAXVAL+1)*alpha_mean);
+    assert(here_int <= AAMAXVAL);
     if (!(here_int==0 || here_int==AAMAXVAL)) monochrome=0;
     cim->d[p.y * cim->w + p.x]= '0' + here_int;
   }
-- 
2.30.2