Better default bounds for Image

Currently, the default behavior for Image is to apply bounds of ±0.5 to both axes. If the original data is not square shaped, the result is a distorted image, as shown below:

%%opts Image (cmap="gray") [aspect='equal']
import holoviews as hv
from scipy import misc
face = misc.face(gray=True)
hv.Image(face)

The original image was 1024x768, but is now shown squashed. When no bounds are specified, the bounds should be set so that the data’s original aspect ratio is preserved, e.g. something like this:

1. Set bounds on x axis to -0.5 and +0.5
2. Set bounds on y axis to -a and +a, where a=data.shape[1]/data.shape[0]*0.5

[drs251]

Or it might be nice to replicate the behaviour of Raster as the default setting, to make it easier to switch between the two. Anyway, as long as the aspect of the original data is preserved, I’d be happy.

[michaelaye]

Do I understand that you propose to not have any class that flips an image array with (0,0) in the top left? I would bet that all image/remote sensing ppl are rather more familiar with that layout, and in fact most space imagery defaults to this. So I vote for having at least one class doing this by default, just as plt.imshow does.