Add image.SubImage, move page-related logic to page.* classes.

pixelocr/image.py

@@ -31,42 +31,70 @@ def _is_nonblank(bitmap):
 class Image(object):
     """Basic image class."""
 
-    child_cls = None
-
     def __init__(self, data):
-        self._data = data
+        self.parent = self
+        self.data = data
+        self.y1 = 0
+        self.y2 = self.width
+        self.x1 = 0
+        self.x2 = self.height
 
     def __getitem__(self, key):
-        return type(self)(self._data.__getitem__(key))
+        """Return a SubImage for the specified region."""
+
+        def indices(sliceobj, length):
+            """Decode a slice object and return a pair of end:start indices."""
+            if sliceobj is None:
+                return 0, length
+            elif isinstance(sliceobj, int):
+                return sliceobj, sliceobj + 1
+            elif isinstance(sliceobj, slice):
+                start, end, stride = sliceobj.indices(length)
+                if stride != 1:
+                    raise NotImplementedError
+                return start, end
+            else:
+                raise NotImplementedError(sliceobj)
+
+        if not isinstance(key, tuple):
+            yslice = key
+            xslice = None
+        else:
+            yslice, xslice = key
+
+        ystart, yend = indices(yslice, self.height)
+        xstart, xend = indices(xslice, self.width)
+
+        y1 = self.y1 + ystart
+        y2 = self.y1 + yend
+        x1 = self.x1 + xstart
+        x2 = self.x1 + xend
+        return SubImage(self.parent, y1, y2, x1, x2)
 
     def _repr_png_(self):
         buf = BytesIO()
-        imsave(buf, self._data)
+        imsave(buf, self.data)
         return buf.getvalue()
 
     @classmethod
     def fromfile(cls, filename):
         return cls(imread(filename))
 
-    @classmethod
-    def space(cls, height, width):
-        return cls(np.ones((height, width)))
-
     @property
     def shape(self):
-        return self._data.shape
+        return self.data.shape
 
-    @property
+    @cached_property
     def T(self):
-        return type(self)(self._data.swapaxes(0, 1))
+        return type(self)(self.data.swapaxes(0, 1))
 
     @property
     def height(self):
-        return self._data.shape[0]
+        return self.data.shape[0]
 
     @property
     def width(self):
-        return self._data.shape[1]
+        return self.data.shape[1]
 
     @cached_property
     def bitmap(self):
@@ -76,7 +104,7 @@ class Image(object):
         1 = black (letter) pixel
         """
 
-        grayscale = rgb2gray(self._data)
+        grayscale = rgb2gray(self.data)
         return (grayscale < 1).astype('b')
 
     @cached_property
@@ -123,10 +151,28 @@ class Image(object):
         bottom_margin = _get_margin_height(reversed(self.bitmap))
         return self[top_margin:self.height - bottom_margin, :]
 
-    def _iter_children(self, min_space):
-        if self.child_cls is None:
-            raise NotImplementedError
 
+class SubImage(Image):
+    def __init__(self, parent, y1, y2, x1, x2):
+        self.parent = parent
+        self.y1 = y1
+        self.y2 = y2
+        self.x1 = x1
+        self.x2 = x2
+
+    @property
+    def data(self):
+        return self.parent.data[self.y1:self.y2, self.x1:self.x2]
+
+    @property
+    def bitmap(self):
+        return self.parent.bitmap[self.y1:self.y2, self.x1:self.x2]
+
+    @property
+    def T(self):
+        return type(self)(self.parent.T, self.x1, self.x2, self.y1, self.y2)
+
+    def _iter_lines(self, min_space, T=False):
         line_start = None
         prev_line_end = 0
 
@@ -136,28 +182,9 @@ class Image(object):
                     line_start = i
                     height = line_start - prev_line_end
                     if height >= min_space:
-                        yield self.child_cls.space(height, self.width)
+                        yield self[prev_line_end:line_start]
             else:
                 if line_start is not None:
-                    yield self.child_cls(self._data[line_start:i, :])
+                    yield self[line_start:i,:]
                     line_start = None  
                     prev_line_end = i
-
-
-class Letter(Image):
-    pass
-
-
-class Line(Image):
-    child_cls = Letter
-
-    def __iter__(self):
-        for rotated_letter in self.T._iter_children(min_space=10):
-            yield rotated_letter.T.strip()
-
-
-class Page(Image):
-    child_cls = Line
-
-    def __iter__(self):
-        return self._iter_children(min_space=200)

pixelocr/page.py

@@ -0,0 +1,77 @@
+# Copyright (C) 2014  Andrey Golovizin
+# 
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+# 
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+from .image import Image
+
+
+class PageObject(object):
+    def __init__(self, image):
+        self.image = image
+
+    def _repr_png_(self):
+        return self.image._repr_png_()
+
+    @property
+    def shape(self):
+        return self.image.shape
+
+    @property
+    def height(self):
+        return self.image.width
+
+    @property
+    def width(self):
+        return self.image.width
+
+    @property
+    def x1(self):
+        return self.image.x1
+
+    @property
+    def x2(self):
+        return self.image.x2
+
+    @property
+    def y1(self):
+        return self.image.y1
+
+    @property
+    def y2(self):
+        return self.image.y2
+
+    @property
+    def x1(self):
+        return self.image.x1
+
+    @property
+    def x2(self):
+        return self.image.x2
+
+
+class Page(PageObject):
+    def __iter__(self):
+        for line_img in self.image._iter_lines(min_space=200):
+            yield Line(line_img)
+
+
+class Line(PageObject):
+    def __iter__(self):
+        for rotated_letter_img in self.image.T._iter_lines(min_space=10, T=True):
+            yield Letter(rotated_letter_img.T.strip())
+
+
+class Letter(PageObject):
+    pass