Add Line.baseline property.

pixelocr/gui/pageview.py

@@ -68,7 +68,8 @@ class PageScene(QGraphicsScene):
                 for letter in word:
                     if not letter.image.isspace:
                         self.addRect(letter.x1, letter.y1, letter.width, letter.height, letterPen, letterBrush)
-            self.addRect(line.x1, line.y1, line.width, line.height, Qt.red)
+            self.addLine(line.x1, line.y1 + line.baseline, line.x2, line.y1 + line.baseline, linePen)
+#             self.addRect(line.x1, line.y1, line.width, line.height, Qt.red)
 
     def addPage(self, page):
         qimage = ndimage2qimage(page.image.data)

pixelocr/page.py

@@ -14,7 +14,9 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 
+import numpy as np
 from scipy import ndimage
+from scipy.ndimage import filters
 
 from .utils import cached_property, collect_iterable
 from .image import Image
@@ -85,6 +87,16 @@ class Line(PageObject):
         for word in self.words:
             yield from word.letters
 
+    @cached_property
+    def baseline(self):
+        """Detect baseline height, relative to the top."""
+        bitmap = self.image.bitmap.astype(np.float)
+        histogram = bitmap.sum(axis=1)
+        gradient = filters.convolve1d(histogram, [1, -1], axis=0)
+        # top = gradient.argmax()
+        bottom = gradient.argmin()
+        return bottom
+
 
 class Word(PageObject):
     def __iter__(self):