Qt-based image reading.

Conflicts:
	scikits/image/io/__init__.py

scikits/image/io/__init__.py

@@ -10,8 +10,8 @@ from _plugins import info as plugin_info
 
 available_plugins = plugins()
 
-for preferred_plugin in ['pil',
-        'matplotlib', 'gtk', 'freeimage', 'qt', 'null']:
+for preferred_plugin in \
+        ['pil', 'matplotlib', 'gtk', 'freeimage', 'qt', 'null']:
     if preferred_plugin in available_plugins:
         use_plugin(preferred_plugin)
         break

scikits/image/io/_plugins/qt_plugin.ini

@@ -1,4 +1,4 @@
 [qt]
 description = Fast image display using the Qt library
-provides = imshow, _app_show, imsave
+provides = imshow, _app_show, imsave, imread
 

scikits/image/io/_plugins/qt_plugin.py

@@ -10,6 +10,8 @@ try:
     from PyQt4.QtGui import (QApplication, QMainWindow, QImage, QPixmap,
                              QLabel, QWidget)
     from PyQt4 import QtCore, QtGui
+    import sip
+    import warnings
 
 except ImportError:
     window_manager._release('qt')
@@ -27,6 +29,7 @@ except ImportError:
 
 app = None
 
+
 class ImageLabel(QLabel):
     def __init__(self, parent, arr):
         QLabel.__init__(self)
@@ -77,6 +80,50 @@ class ImageWindow(QMainWindow):
         self.mgr.remove_window(self)
 
 
+def imread_qt(filename):
+    """
+    Read an image using QT's QImage.load
+    """
+    qtimg = QImage()
+    if not qtimg.load(filename):
+        # QImage.load() returns false on failure, so raise an exception
+        raise IOError('Unable to load file %s' % filename)
+    if qtimg.depth() == 1:
+        raise IOError('1-bit images currently not supported')
+    # TODO: Warn about other odd formats we don't currently handle properly,
+    # such as the odd 16-bit packed formats QT supports
+    arrayptr = qtimg.bits()
+    # QT may pad the image, so we need to use bytesPerLine, not width for
+    # the conversion to a numpy array
+    bytesPerPixel = qtimg.depth() // 8
+    pixelsPerLine = qtimg.bytesPerLine() // bytesPerPixel
+    img_size = pixelsPerLine * qtimg.height() * bytesPerPixel
+    arrayptr.setsize(img_size)
+    img = np.array(arrayptr)
+    # Reshape and trim down to correct dimensions
+    if bytesPerPixel > 1:
+        img = img.reshape((qtimg.height(), pixelsPerLine, bytesPerPixel))
+        img = img[:, :qtimg.width(), :]
+    else:
+        img = img.reshape((qtimg.height(), pixelsPerLine))
+        img = img[:, :qtimg.width()]
+    # Strip qt's false alpha channel if needed
+    # and reorder color axes as required
+    if bytesPerPixel == 4 and not qtimg.hasAlphaChannel():
+        img = img[:, :, 2::-1]
+    elif bytesPerPixel == 4:
+        img[:, :, 0:3] = img[:, :, 2::-1]
+    return img
+
+if sip.SIP_VERSION >= 0x040c00:
+    # sip.voidptr only acquired a buffer view in 4.12.0, so our imread
+    # doesn't work with earlier versions
+    imread = imread_qt
+else:
+    warnings.warn(RuntimeWarning(
+        "sip version too old. QT imread disabled"))
+
+
 def imshow(arr, fancy=False):
     global app
     if not app:

scikits/image/io/_plugins/util.py

@@ -135,14 +135,15 @@ def prepare_for_display(npy_img):
 
     if npy_img.ndim == 2 or \
        (npy_img.ndim == 3 and npy_img.shape[2] == 1):
+        npy_plane = npy_img.reshape((height, width))
         if np.issubdtype(npy_img.dtype, float):
-            out[:,:,0] = npy_img*255
+            out[:,:,0] = npy_plane*255
             out[:,:,1] = out[:,:,0]
             out[:,:,2] = out[:,:,0]
         else:
-            out[:,:,0] = npy_img
-            out[:,:,1] = npy_img
-            out[:,:,2] = npy_img
+            out[:,:,0] = npy_plane
+            out[:,:,1] = npy_plane
+            out[:,:,2] = npy_plane
 
     elif npy_img.ndim == 3:
         if npy_img.shape[2] == 3 or npy_img.shape[2] == 4: