# HG changeset patch
# User carandraug
# Date 1323060119 0
# Node ID 9135e5461550ffbe31d318804e34a4ce640ab799
# Parent  7d8494a6d8a6af29b7ab7ad9258b310e68883193
isgray isbw isrgb: return false is argument is empty matrix

diff --git a/inst/isbw.m b/inst/isbw.m
--- a/inst/isbw.m
+++ b/inst/isbw.m
@@ -37,7 +37,7 @@
   endif
 
   ## an image cannot be a sparse matrix
-  if (!ismatrix (BW) || issparse (BW))
+  if (!ismatrix (BW) || issparse (BW) || isempty (BW))
     bool = false;
   elseif (strcmpi (logic, "logical"))
     ## this is the matlab compatible way (before they removed the function)
diff --git a/inst/isgray.m b/inst/isgray.m
--- a/inst/isgray.m
+++ b/inst/isgray.m
@@ -38,7 +38,7 @@
   endif
 
   bool = false;
-  if (ismatrix (img) && ndims (img) == 2 && !issparse (img))
+  if (ismatrix (img) && ndims (img) == 2 && !issparse (img) && !isempty (img))
     switch (class (img))
       case "double"
         ## to speed this up, we can look at a sample of the image first
diff --git a/inst/isrgb.m b/inst/isrgb.m
--- a/inst/isrgb.m
+++ b/inst/isrgb.m
@@ -39,7 +39,7 @@
   endif
 
   bool = false;
-  if (ismatrix (img) && ndims (img) == 3 && size (img, 3) == 3 && !issparse (img))
+  if (ismatrix (img) && ndims (img) == 3 && size (img, 3) == 3 && !issparse (img) && !isempty (img))
     switch (class (img))
       case "double"
         ## to speed this up, we can look at a sample of the image first