Make baseline be exactly _below_ the letter.

The letter now "sits" on the baseline. This is to make indexing more convenient.

pixelocr/gui/pageview.py

@@ -68,7 +68,7 @@ class PageScene(QGraphicsScene):
                 for letter in word:
                     if not letter.image.isspace:
                         self.addRect(letter.x1, letter.y1, letter.width - 1, letter.height - 1, letterPen, letterBrush)
-            self.addLine(line.x1, line.y1 + line.baseline, line.x2, line.y1 + line.baseline, linePen)
+            self.addLine(line.x1, line.y1 + line.baseline, line.x2, line.y1 + line.baseline - 1, linePen)
 #             self.addRect(line.x1, line.y1, line.width, line.height, Qt.red)
 
     def addPage(self, page):

pixelocr/page.py

@@ -92,7 +92,7 @@ class Line(PageObject):
         """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)
+        gradient = filters.correlate1d(histogram, [-1, 1], axis=0)
         # top = gradient.argmax()
         bottom = gradient.argmin()
         return bottom