Do not negate Sauvola's output.

	* scribo/toolchain/text_in_doc_preprocess.hh,
	* scribo/toolchain/text_in_picture.hh: Do not negate Sauvola's
          output anymore.

scribo/scribo/toolchain/text_in_doc_preprocess.hh

@@ -32,7 +32,6 @@
 
 
 #include <mln/core/concept/image.hh>
-#include <mln/logical/not.hh>
 
 #include <scribo/binarization/sauvola_ms.hh>
 
@@ -157,8 +156,6 @@ namespace scribo
       mln_ch_value(I,bool)
 	input_bin = scribo::binarization::sauvola_ms(input_gl, 101, 3);
 
-      logical::not_inplace(input_bin);
-
       trace::exiting("scribo::toolchain::text_in_doc_preprocess");
       return input_bin;
     }

scribo/scribo/toolchain/text_in_picture.hh

@@ -221,12 +221,6 @@ namespace scribo
 		      scribo::make::debug_filename("binarization.pbm"));
       }
 
-
-      // Yeah, looks strange, but we need to negate by default to
-      // process dark objects on light background.
-      if (!negate)
-	logical::not_inplace(input);
-
       t_ = timer_;
       std::cout << "Foreground binarized. " << t_ << std::endl;