Clean background

AUTHORS

@@ -4,6 +4,7 @@ Adam Langley <agl@imperialviolet.org>
 
 Contributors:
 =============
+Dan Bloomberg <dan.bloomberg@gmail.com>
 Misty De Meo <mistydemeo@gmail.com>
 zdenop <zdenop@gmail.com>
 Steven Lee http://www.rubypdf.com

src/jbig2.cc

@@ -62,6 +62,8 @@ usage(const char *argv0) {
   fprintf(stderr, "  -t <threshold>: set classification threshold for symbol coder (def: %0.2f)\n", JBIG2_THRESHOLD_DEF);
   fprintf(stderr, "  -w <weight>: set classification weight for symbol coder (def: %0.2f)\n", JBIG2_WEIGHT_DEF);
   fprintf(stderr, "  -T <bw threshold>: set 1 bpp threshold (def: %d)\n", BW_THRESHOLD_DEF);
+  fprintf(stderr, "  -G --global: simply threshold for BW images\n");
+  fprintf(stderr, "  -N --normalize: background clean/normalize\n");
   fprintf(stderr, "  -r --refine: use refinement (requires -s: lossless)\n");
   fprintf(stderr, "  -O <outfile>: dump thresholded image as PNG\n");
   fprintf(stderr, "  -2: upsample 2x before thresholding\n");
@@ -213,9 +215,12 @@ int
 main(int argc, char **argv) {
   bool duplicate_line_removal = false;
   bool pdfmode = false;
+  bool globalmode = false;
+  bool bgnmode = false;
   float threshold = JBIG2_THRESHOLD_DEF;
   float weight = JBIG2_WEIGHT_DEF;
   int bw_threshold = BW_THRESHOLD_DEF;
+  int bwthresdelta = 0;
   bool symbol_mode = false;
   bool refine = false;
   bool up2 = false, up4 = false;
@@ -320,9 +325,11 @@ main(int argc, char **argv) {
         return 1;
       }
 
-      if ((threshold < JBIG2_THRESHOLD_MIN) || (threshold > JBIG2_THRESHOLD_MAX)) {
+      if ((threshold < JBIG2_THRESHOLD_MIN) ||
+          (threshold > JBIG2_THRESHOLD_MAX)) {
         fprintf(stderr, "Invalid value for threshold\n");
-        fprintf(stderr, "(must be between %0.2f and %0.2f)\n", JBIG2_THRESHOLD_MIN, JBIG2_THRESHOLD_MAX);
+        fprintf(stderr, "(must be between %0.2f and %0.2f)\n",
+                JBIG2_THRESHOLD_MIN, JBIG2_THRESHOLD_MAX);
         return 10;
       }
       i++;
@@ -340,29 +347,32 @@ main(int argc, char **argv) {
 
       if ((weight < JBIG2_WEIGHT_MIN) || (weight > JBIG2_WEIGHT_MAX)) {
         fprintf(stderr, "Invalid value for weight\n");
-        fprintf(stderr, "(must be between %0.2f and %0.2f)\n", JBIG2_WEIGHT_MIN, JBIG2_WEIGHT_MAX);
+        fprintf(stderr, "(must be between %0.2f and %0.2f)\n",
+                JBIG2_WEIGHT_MIN, JBIG2_WEIGHT_MAX);
         return 10;
       }
       i++;
       continue;
     }
 
     if (strcmp(argv[i], "-T") == 0) {
-      char *endptr;
-      bw_threshold = strtol(argv[i+1], &endptr, 10);
-      if (*endptr) {
-        fprintf(stderr, "Cannot parse int value: %s\n", argv[i+1]);
-        usage(argv[0]);
-        return 1;
-      }
-      if (bw_threshold < BW_THRESHOLD_MIN || bw_threshold > BW_THRESHOLD_MAX) {
-        fprintf(stderr, "Invalid bw threshold: (%d..%d)\n", BW_THRESHOLD_MIN, BW_THRESHOLD_MAX);
-        return 11;
-      }
+      fprintf(stderr, "Binary thresholds 'T' are no longer used\n");
       i++;
       continue;
     }
 
+    if (strcmp(argv[i], "-G") == 0 ||
+        strcmp(argv[i], "--global") == 0) {
+      globalmode = true;
+      continue;
+    }
+
+    if (strcmp(argv[i], "-N") == 0 ||
+        strcmp(argv[i], "--normalize") == 0) {
+      bgnmode = true;
+      continue;
+    }
+
     // engage auto thresholding
     if (strcmp(argv[i], "--auto-thresh") == 0 ||
         strcmp(argv[i], "-a") == 0 ) {
@@ -421,6 +431,11 @@ main(int argc, char **argv) {
   struct jbig2ctx *ctx = jbig2_init(threshold, weight, 0, 0, !pdfmode, refine ? 10 : -1);
   int pageno = -1;
 
+ if (!globalmode) {
+    bwthresdelta = (bgnmode) ? 0 : 64;
+    bw_threshold = ((bw_threshold + bwthresdelta) < 256) ? (bw_threshold + bwthresdelta) : 255;
+  }
+
   int numsubimages=0, subimage=0, num_pages = 0;
   while (i < argc) {
     if (subimage==numsubimages) {
@@ -456,7 +471,7 @@ main(int argc, char **argv) {
     if (verbose)
       pixInfo(source, "source image:");
 
-    PIX *pixl, *gray, *pixt;
+    PIX *pixl, *gray, *adapt, *pixt;
     if ((pixl = pixRemoveColormap(source, REMOVE_CMAP_BASED_ON_SRC)) == NULL) {
       fprintf(stderr, "Failed to remove colormap from %s\n", argv[i]);
       return 1;
@@ -474,7 +489,13 @@ main(int argc, char **argv) {
         fprintf(stderr, "Unsupported input image depth: %d\n", pixl->d);
         return 1;
       }
-      Pix *adapt = pixBackgroundNormSimple(gray, NULL, NULL);
+      if (globalmode) {
+        adapt = pixClone(gray);
+      } else if (bgnmode) {
+        adapt = pixBackgroundNormSimple(gray, NULL, NULL);
+      } else {
+        adapt = pixCleanBackgroundToWhite(gray, NULL, NULL, 1.0, 90, 190);
+      }
       pixDestroy(&gray);
       if (up2) {
         pixt = pixScaleGray2xLIThresh(adapt, bw_threshold);