`ndArrayToQtImage` fails for certain image sizes

Images with certain dimensions fail to display correctly under Qt after conversion.  E.g., an `(187, 189)` image displays as diagonal bands.  Use the following snippet to produce a suitable test image:

``` python
import numpy as np
import matplotlib.pyplot as plt

image = np.zeros((187, 189))
image[:] = np.arange(189)

plt.imsave('gradient.png', image, cmap=plt.cm.gray)
```
