Fixed pixCropImage() when aggressively cropping 2-column material.

* So it selects both columns, not just the one with largest area.

prog/croppdf.c

@@ -39,7 +39,7 @@
  *
  *    Syntax:
  *       croppdf basedir lrclear tbclear edgeclean lradd tbadd maxwiden
- *       title fileout
+ *       printwiden title fileout
  *
  *    The %basedir is a directory where the input pdf files are located.
  *    The program will operate on every file in this directory with
@@ -62,6 +62,11 @@
  *    8.5 x 11 inch printed page.  It gives the maximum fractional horizontal
  *    stretching allowed.  Suggested values are between 1.0 and 1.15.
  *
+ *    If you are not concerned with printing on paper, use the default
+ *    value 0 for %printwiden to skip; 1 for 8.5 x 11 paper; 2 for A4.
+ *    Widening only takes place if the ratio h/w exceeds the specified paper
+ *    size by 3%, and the horizontal scaling factor will not exceed 1.20.
+ *
  *    The %title is the title given to the pdf.  Use %title == "none"
  *    to omit the title.
  *

src/pageseg.c

@@ -34,7 +34,6 @@
  *      Halftone region extraction
  *          PIX      *pixGenHalftoneMask()    **Deprecated wrapper**
  *          PIX      *pixGenerateHalftoneMask()
-
  *
  *      Textline extraction
  *          PIX      *pixGenTextlineMask()
@@ -559,8 +558,10 @@ PIX     *pix1, *pix2, *pix3, *pixd;
  *          (c) If %edgeclean > 0, it removes isolated sets of pixels,
  *              using a close/open operation of size %edgeclean + 1.
  *              If %edgeclean < 0, it uses a large vertical morphological
- *              closing and the extraction of the largest resulting
- *              connected component to eliminate noise on left and right sides.
+ *              close/open and the extraction of either the largest
+ *              resulting connected component (or the largest two components
+ *              if the page has 2 columns), to eliminate noise on left
+ *              and right sides.
  *          (d) Find the bounding box of remaining fg pixels and scales
  *              the box up 2x back to full resolution.
  *          (e) Crops the binarized image to the bounding box.
@@ -705,14 +706,15 @@ PIXA      *pixa1;
         /* Optionally widen image if possible, for printing on 8.5 x 11 inch
          * or A4 paper.  Specifically, widen the image if the h/w asperity
          * ratio of the input image exceeds that of the selected paper by
-         * more than 3%.  Do not widen by more than 25%.  */
+         * more than 3%.  Do not widen by more than 20%.  */
     r1 = (l_float32)h / (l_float32)w;
     r2 = 0.0;  /* for default case */
     if (printwiden == 1)  /* standard */
         r2 = r1 / 1.294;
     else if (printwiden == 2)  /* A4 */
         r2 = r1 / 1.414;
     if (r2 > 1.03) {
+        r2 = L_MIN(r2, 1.20);
         lept_stderr("oversize h/w ratio by factor %6.3f\n", r2);
         pix4 = pixScale(pix3, r2, 1.0);
     } else {
@@ -748,18 +750,21 @@ PIXA      *pixa1;
  *          at the input resolution.
  *      (2) The input %pixs should be at a resolution 100 - 150 ppi.
  *      (3) It does two 2x level1 rank binary reductions, followed
- *          by a large vertical close/open, and then a 4x expansion
- *          back to the input resolution.
- *      (4) It is used as an option to pixCropImage(), when given
+ *          by a large vertical close/open, with a very small horizontal
+ *          close/oopen, and then a 4x expansion back to the input resolution.
+ *      (4) To work properly with 2-column layout, if the largest and
+ *          second-largest regions are comparable in size, both are included.
+ *      (5) This is used as an option to pixCropImage(), when given
  *          a negative %edgecrop parameter.
  * </pre>
  */
 l_int32
 pixMaxCompAfterVClosing(PIX   *pixs,
                         BOX  **pbox)
 {
-l_int32  w, h, i, n, maxindex, maxarea, empty;
-BOXA    *boxa1;
+l_int32  w1, h1, w2, h2, n, empty;
+BOX     *box1, *box2;
+BOXA    *boxa1, *boxa2;
 PIX     *pix1;
 
     if (!pbox)
@@ -769,26 +774,35 @@ PIX     *pix1;
         return ERROR_INT("pixs undefined or not 1 bpp", __func__, 1);
 
         /* Strong vertical closing */
-    pix1 = pixMorphSequence(pixs, "r11 + c1.50 + o1.50 + x4", 0);
+    pix1 = pixMorphSequence(pixs, "r11 + c3.80 + o3.80 + x4", 0);
     pixZero(pix1, &empty);
     if (empty)
         return ERROR_INT("pix1 is empty", __func__, 1);
 
-        /* Find the c.c. with largest area and return its bounding box */
+        /* Find the two c.c. with largest area. If they are not comparable
+         * in area, return the bounding box of the largest; otherwise,
+         * return the bounding box of both regions. */
     boxa1 = pixConnCompBB(pix1, 8);
     pixDestroy(&pix1);
-    n = boxaGetCount(boxa1);
-    maxindex = 0;
-    maxarea = 0;
-    for (i = 0; i < n; i++) {
-        boxaGetBoxGeometry(boxa1, i, NULL, NULL, &w, &h);
-        if (w * h > maxarea) {
-            maxarea = w * h;
-            maxindex = i;
+    boxa2 = boxaSort(boxa1, L_SORT_BY_AREA, L_SORT_DECREASING, NULL);
+    box1 = boxaGetBox(boxa2, 0, L_COPY);
+    if ((n = boxaGetCount(boxa2)) == 1) {
+        *pbox = box1;
+    } else {  /* 2 or more */
+        box1 = boxaGetBox(boxa2, 0, L_COPY);
+        box2 = boxaGetBox(boxa2, 1, L_COPY);
+        boxGetGeometry(box1, NULL, NULL, &w1, &h1);
+        boxGetGeometry(box2, NULL, NULL, &w2, &h2);
+        if (((l_float32)(w2 * h2) / (l_float32)(w1 * h1)) > 0.7) {
+            *pbox = boxBoundingRegion(box1, box2);
+            boxDestroy(&box1);
+        } else {
+            *pbox = box1;
         }
+        boxDestroy(&box2);
     }
-    *pbox = boxaGetBox(boxa1, maxindex, L_COPY);
     boxaDestroy(&boxa1);
+    boxaDestroy(&boxa2);
     return 0; 
 }