new file mode 100644
--- /dev/null
+++ b/inst/imbothat.m
@@ -0,0 +1,52 @@
+## Copyright (C) 2005  Carvalho-Mariel
+## Copyright (C) 2010-2011 Carnë Draug <carandraug+dev@gmail.com>
+## 
+## This program is free software; you can redistribute it and/or
+## modify it under the terms of the GNU General Public License
+## as published by the Free Software Foundation; either version 2
+## of the License, or (at your option) any later version.
+## 
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} @var{B} = imbothat (@var{A}, @var{se})
+## Perform morphological bottom hat filtering.
+##
+## The image @var{A} must be a grayscale or binary image, and @var{se} must be a
+## structuring element. Both must have the same class, e.g., if @var{A} is a
+## logical matrix, @var{se} must also be logical.
+##
+## A bottom-hat transform is also known as 'black', or 'closing', top-hat
+## transform.
+##
+## @seealso{imerode, imdilate, imopen, imclose, imtophat, mmgradm}
+## @end deftypefn
+
+function retval = imbothat (im, se)
+
+  ## Checkinput
+  if (nargin <=1 || nargin > 3)
+    print_usage();
+  endif
+  if (!ismatrix(im) || !isreal(im))
+    error("imtophat: first input argument must be a real matrix");
+  elseif (!ismatrix(se) || !isreal(se))
+    error("imtophat: second input argument must be a real matrix");
+  elseif ( !strcmp(class(im), class(se)) )
+    error("imtophat: image and structuring element must have the same class");
+  endif
+
+  ## Perform filtering
+  ## Note that in case that the transform is to applied to a logical image,
+  ## subtraction must be handled in a different way (x & !y) instead of (x - y)
+  ## or it will return a double precision matrix
+  if (islogical(im))
+    retval = imclose(im, se) & !im;
+  else
+    retval = imclose(im, se) - im;
+  endif
+
+endfunction

--- a/inst/imtophat.m
+++ b/inst/imtophat.m
@@ -1,5 +1,5 @@
 ## Copyright (C) 2005  Carvalho-Mariel
-## Copyright (C) 2010  Carnë Draug <carandraug+dev@gmail.com>
+## Copyright (C) 2010-2011 Carnë Draug <carandraug+dev@gmail.com>
 ## 
 ## This program is free software; you can redistribute it and/or
 ## modify it under the terms of the GNU General Public License
@@ -26,10 +26,13 @@
 ## or @code{black}. If @var{type} is not specified, it performs a white top-hat
 ## transform.
 ##
-## @seealso{imerode, imdilate, imopen, imclose, mmgradm}
+## A 'black', or 'closing', top-hat transform is also known as bottom-hat
+## transform and so that is the same @code{imbothat}.
+##
+## @seealso{imerode, imdilate, imopen, imclose, imbothat, mmgradm}
 ## @end deftypefn
 
-function retval = imtophat(im, se, trans)
+function retval = imtophat (im, se, trans)
 
   ## Checkinput
   if (nargin <=1 || nargin > 3)
@@ -56,11 +59,7 @@
       retval = im - imopen(im, se);
     endif
   elseif ( strcmpi(trans, "black") || strcmpi(trans, "close") )
-    if (islogical(im))
-      retval = imclose(im, se) & !im;
-    else
-      retval = imclose(im, se) - im;
-    endif
+    retval = imbothat (im, se);
   else
     error ("Unexpected type of top-hat transform");
   endif
@@ -77,5 +76,3 @@
 %! result = imtophat((I), (se));
 %! expected = [0 0 1; 0 0 1; 1 1 1];
 %! assert(expected, result);
-
-