Add QT4 image display plugin.

scikits/image/io/__init__.py

@@ -2,6 +2,7 @@
 
 import pil_plugin
 import matplotlib_plugin
+import qt_plugin
 
 from plugin import register as register_plugin
 

scikits/image/io/qt_plugin.py

@@ -0,0 +1,31 @@
+import plugin
+import numpy as np
+
+try:
+    from PyQt4.QtGui import QApplication, QImage, QPixmap, QLabel
+except ImportError:
+    have_qt = False
+else:
+    have_qt = True
+
+def show(arr):
+    arr = np.ascontiguousarray(arr.astype(np.uint8))
+    if arr.ndim != 3:
+        raise ValueError("Qt only displays colour images.")
+
+    if arr.shape[-1] == 4:
+        raise ValueError("Alpha channels not yet supported.")
+
+    img = QImage(arr.data, arr.shape[1], arr.shape[0], QImage.Format_RGB888)
+    pm = QPixmap.fromImage(img)
+
+    app = QApplication([])
+
+    label = QLabel()
+    label.setPixmap(pm)
+    label.show()
+
+    app.exec_()
+
+if have_qt:
+    plugin.register('qt', show=show)