[Rapp-dev] Please also look at 7b42, fixing binary morph padding

[Hans-Peter Nilsson]

As discussed, the overlap checks as well as the recent
documentation adjustment required one more pixel padding than
necessary.  Also, the overlap-check for rectangular SE's didn't
check what the documentation mandated.  Usually
misunderstandings like this is a sign that the documentation
needed clarification, so done.  Please have a look.

commit 7b42332c43bbab521408770faffe04b500e7094b
Author: Hans-Peter Nilsson <address@hidden>
Date:   Mon Dec 13 05:02:58 2010 +0100

    Fix rectangular binary morphology overlap padding check and revert previous 
change. Clarify docs.
    
        * driver/rapp_morph_bin.c (rapp_morph_erode_rect_bin)
        (rapp_morph_dilate_rect_bin): Adjust to documentation; when
        checking for buffer overlap, actually check that all padding is
        according to half the *max* side of the SE, and rounding
        downwards, not upwards.
        (rapp_morph_isotropic): Similarly, check overlap for padding to
        radius minus one, not radius.
        * include/rapp_morph_bin.h (Padding): Revert previous change.
        Clarify bounds of padding for both cases, isotropic and
        rectangular elements.
        * test/rapp_test_morph_bin.c (rapp_test_rectangle_driver): Adjust
        accordingly.  Tighten up, use only the necessary padding.
        (rapp_test_isotropic_driver): Ditto.
    
    Mention version and refer to project URL in doc and dev-doc.
    Read URL from README.  Rerun autogen.sh.

diff --git a/driver/rapp_morph_bin.c b/driver/rapp_morph_bin.c
index 0f7db43..ea90f87 100644
--- a/driver/rapp_morph_bin.c
+++ b/driver/rapp_morph_bin.c
@@ -428,8 +428,9 @@ RAPP_API(int, rapp_morph_erode_rect_bin,
           int width, int height, int wrect, int hrect,
           void *restrict work))
 {
-    int minxpadding = rc_align((MIN((wrect + 1) / 2, 16) + 7) / 8);
-    int minypadding = MIN((hrect + 1) / 2, 16);
+    int maxside     = MAX(wrect, hrect);
+    int minxpadding = rc_align((MIN(maxside / 2, 16) + 7) / 8);
+    int minypadding = MIN(maxside / 2, 16);
 
     if (!RAPP_INITIALIZED()) {
         return RAPP_ERR_UNINITIALIZED;
@@ -526,8 +527,9 @@ RAPP_API(int, rapp_morph_dilate_rect_bin,
           int width, int height, int wrect, int hrect,
           void *restrict work))
 {
-    int minxpadding = rc_align((MIN((wrect + 1) / 2, 16) + 7) / 8);
-    int minypadding = MIN((hrect + 1) / 2, 16);
+    int maxside     = MAX(wrect, hrect);
+    int minxpadding = rc_align((MIN(maxside / 2, 16) + 7) / 8);
+    int minypadding = MIN(maxside / 2, 16);
 
     if (!RAPP_INITIALIZED()) {
         return RAPP_ERR_UNINITIALIZED;
@@ -746,8 +748,8 @@ rapp_morph_isotropic(uint8_t *dst, int dst_dim,
     uint8_t *tmp1;
     uint8_t *tmp2;
     int      dim;
-    int      minxpadding = rc_align((MIN(radius, 16) + 7) / 8);
-    int      minypadding = MIN(radius, 16);
+    int      minxpadding = rc_align((MIN(radius - 1, 16) + 7) / 8);
+    int      minypadding = MIN(radius - 1, 16);
 
     if (!RAPP_INITIALIZED()) {
         return RAPP_ERR_UNINITIALIZED;
diff --git a/include/rapp_morph_bin.h b/include/rapp_morph_bin.h
index 8263ffb..3fa3962 100644
--- a/include/rapp_morph_bin.h
+++ b/include/rapp_morph_bin.h
@@ -70,10 +70,14 @@
  *
  *  @section Padding
  *  The user is responsible for @ref padding "padding" the source buffer.
- *  The padding needed is bounded by min((size + 1) / 2, 16), where size
- *  is the maximum size of the structuring element in the horizontal
- *  and vertical directions. If the source buffer is padded with
- *  values other than all-zeros or all-ones the behaviour is undefined.
+ *  The padding needed is the same both in horizontal and vertical
+ *  directions. For rectangular structuring elements, it is bounded by
+ *  min(maxside / 2, 16), where maxside is the maximum size of the
+ *  structuring element in the horizontal and vertical directions, and
+ *  maxside / 2 is rounded <em>down</em> to the nearest integer. For
+ *  other objects, the padding is bounded by min(radius - 1, 16). If the
+ *  source buffer is padded with values other than all-zeros or all-ones
+ *  the behaviour is undefined.
  *
  *  <p>@ref padding "Next section: Border Padding"</p>
  *
diff --git a/test/rapp_test_morph_bin.c b/test/rapp_test_morph_bin.c
index 241032a..da6f7f8 100644
--- a/test/rapp_test_morph_bin.c
+++ b/test/rapp_test_morph_bin.c
@@ -386,16 +386,18 @@ rapp_test_rectangle_driver(int (*morph)(), int width,
     int      dst_dim;         /* Destination buffer dimension  */
     int      pad_len;         /* Padded source buffer in bytes */
     int      size    = MIN(width, height);
+    int      minpixpad = MIN(MAX(width, height) / 2, 16);
+    int      minxpad = rapp_align((minpixpad + 7) / 8);
     int      pos;
     bool     ok = false;
 
     /* Allocate the buffers */
     dst_dim = rapp_align((width + 7) / 8);
-    src_dim = dst_dim + 2*rapp_alignment;
+    src_dim = dst_dim + 2*minxpad;
     pat_buf = rapp_malloc(height*dst_dim, 0);
-    pad_len = (height + 2*16)*src_dim;
+    pad_len = (height + 2*minpixpad)*src_dim;
     pad_buf = rapp_malloc(pad_len, 0);
-    src_buf = &pad_buf[16*src_dim + rapp_alignment];
+    src_buf = &pad_buf[minpixpad*src_dim + minxpad];
     dst_buf = rapp_malloc(height*dst_dim, 0);
     ref_buf = rapp_malloc(height*dst_dim, 0);
     work    = rapp_malloc(rapp_morph_worksize_bin(width, height), 0);
@@ -410,13 +412,11 @@ rapp_test_rectangle_driver(int (*morph)(), int width,
                  width, height, work) != RAPP_ERR_OVERLAP
         /* src = far end of dst */
         || (*morph)(dst_buf, dst_dim,
-                    dst_buf + dst_dim*(height - 1) +
-                    rapp_align((width + 7) / 8) - rapp_alignment, src_dim,
+                    dst_buf + dst_dim*height + minxpad - rapp_alignment, 
src_dim,
                     width, height, width, height, work) != RAPP_ERR_OVERLAP
         /* src = before dst, but not long enough */
         || (*morph)(dst_buf, dst_dim,
-                    dst_buf - (dst_dim*(height - 1) +
-                               rapp_align((width + 7) / 8) - rapp_alignment),
+                    dst_buf - (dst_dim*height + minxpad - rapp_alignment),
                     src_dim,
                     width, height, width, height, work) != RAPP_ERR_OVERLAP
         /* dst = work */
@@ -519,6 +519,8 @@ rapp_test_isotropic_driver(int (*morph)(), int radius, int 
area, bool dilate)
     int      pad_len;         /* Padded source buffer in bytes */
     int      pos;
     int      size    = 2*radius - 1;
+    int      minpixpad = MIN(radius - 1, 16);
+    int      minxpad = rapp_align((minpixpad + 7) / 8);
     bool     ok      = false;
 
     /* Get the SE pattern image */
@@ -531,10 +533,10 @@ rapp_test_isotropic_driver(int (*morph)(), int radius, 
int area, bool dilate)
     }
 
     /* Allocate the buffers */
-    src_dim = dst_dim + 2*rapp_alignment;
-    pad_len = (size + 2*16)*src_dim;
+    src_dim = dst_dim + 2*minxpad;
+    pad_len = (size + 2*minpixpad)*src_dim;
     pad_buf = rapp_malloc(pad_len, 0);
-    src_buf = &pad_buf[16*src_dim + rapp_alignment];
+    src_buf = &pad_buf[minpixpad*src_dim + minxpad];
     dst_buf = rapp_malloc(size*dst_dim, 0);
     ref_buf = rapp_malloc(size*dst_dim, 0);
     work    = rapp_malloc(rapp_morph_worksize_bin(size, size), 0);
@@ -545,13 +547,11 @@ rapp_test_isotropic_driver(int (*morph)(), int radius, 
int area, bool dilate)
                  work) != RAPP_ERR_OVERLAP
         /* src = far end of dst */
         || (*morph)(dst_buf, dst_dim,
-                    dst_buf + dst_dim*(size - 1) +
-                    rapp_align((size + 7) / 8) - rapp_alignment, src_dim,
+                    dst_buf + dst_dim*size + minxpad - rapp_alignment, src_dim,
                     size, size, radius, work) != RAPP_ERR_OVERLAP
         /* src = before dst, but not long enough */
         || (*morph)(dst_buf, dst_dim,
-                    dst_buf - (dst_dim*(size - 1) +
-                               rapp_align((size + 7) / 8) - rapp_alignment),
+                    dst_buf - (dst_dim*size + minxpad - rapp_alignment),
                     src_dim,
                     size, size, radius, work) != RAPP_ERR_OVERLAP
         /* dst = work */

brgds, H-P