Add lineart transformation.

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

HISTORY.rst

@@ -2,6 +2,9 @@
 ===============
 - Add view to download a document's OCR text. GitLab #215
 - Add user configurable mailer. GitLab #286.
+- Use Toasts library for screen messages.
+- Reduce verbosity of some debug messages.
+- Add new lineart transformation.
 
 2.4 (2017-06-23)
 ================

docs/releases/2.5.rst

@@ -24,6 +24,10 @@ Other Changes
 - Make the task manager translatable.
 - Add Turkish to the list of processes languages.
 - Add user configurable mailer support. GitLab issue #286.
+- Use Toastr libary for screen messages.
+- Reduce verbosity of some debug messages.
+- New lineart transformation. Useful to increase the OCR accuracy on some kind
+  of documents.
 
 Removals
 --------

mayan/apps/converter/classes.py

@@ -324,6 +324,16 @@ class TransformationGaussianBlur(BaseTransformation):
         return self.image.filter(ImageFilter.GaussianBlur(radius=self.radius))
 
 
+class TransformationLineArt(BaseTransformation):
+    label = _('Line art')
+    name = 'lineart'
+
+    def execute_on(self, *args, **kwargs):
+        super(TransformationLineArt, self).execute_on(*args, **kwargs)
+
+        return self.image.convert('L').point(lambda x: 0 if x < 128 else 255, '1')
+
+
 class TransformationMirror(BaseTransformation):
     arguments = ()
     label = _('Mirror')
@@ -452,6 +462,7 @@ class TransformationZoom(BaseTransformation):
 BaseTransformation.register(TransformationCrop)
 BaseTransformation.register(TransformationFlip)
 BaseTransformation.register(TransformationGaussianBlur)
+BaseTransformation.register(TransformationLineArt)
 BaseTransformation.register(TransformationMirror)
 BaseTransformation.register(TransformationResize)
 BaseTransformation.register(TransformationRotate)
@@ -460,3 +471,7 @@ BaseTransformation.register(TransformationRotate180)
 BaseTransformation.register(TransformationRotate270)
 BaseTransformation.register(TransformationUnsharpMask)
 BaseTransformation.register(TransformationZoom)
+
+
+
+