Display Image in Qtconsole

[Carreau]

hi,

playing with notebook_00 code in qtconsole I saw that :

from IPython.core.display import *
Image('http://python.org/images/python-logo.gif')

Does not display the image in qtconsole
It seems that it works by setting embed=True as a kwarg, but the docstring state that (emphase mine):

embed : bool
    Should the image data be embedded in the **notebook** using a data URI (True)
    or be loaded using an <img> tag. Set this to True if you want the image
    to be viewable later with no internet connection. **If a filename** is given
    embed is always set to **True**.

Which don't give any clue as wether embed is needed for other frontend than notebook.
Moreover 'if a filename' seem to mean that if the (first) argument given to Image is a filename, the embed is automaticaly set to true, whereas the code set embed to True if and only if the filename **kwarg** is not None.

I suggest setting embed to True after super as been initiated if either self.filename or self.url are not None to be able to display the Image in QtConsole by just dooing Image(url or filename). Unless of course there is a good reason not to...

[minrk]

Unless of course there is a good reason not to...

embed should be False if a url is given, because that means the display data need only be <img src="url"/>, rather than including base64-encoded data. This is a highly Notebook-centric behavior, as the QtConsole does not support non-embedded images at all, but it is so much better in the notebook, that I think it's still the right choice.

Another solution would be to enable support for <img src="url"> in the QtConsole. I have no idea what that would require.

[minrk]

But I think you make a good point that a note should be added that the QtConsole only supports embedded images.

[Carreau]

Well, there is still the problem that having embeded=False For URL make the image disapearing if there is no internet connexion, if it's removed...etc

I would change the behavior to embed=True unless url kwarg is explicitely given or embed=False is explicitely given, so that notebook are always readable offline, and there is the least surprise when moving code from notebook to qtconsole.

In fine this is your call, but that how I feel for using Image for the first time. It feel to me that like %loadpy, using an url as first argument (by opsition as usin url kwarg) is fetching the data magically.

If it's a question of size of the notebook, I don't think an image will make much difference in size with lot of graph embeded.

[minrk]

I would change the behavior to embed=True unless url kwarg is explicitly given

This seems pretty reasonable to me. From the notebook's perspective, I still think when an Image is given by URL, it rarely is actually desirable to embed the image, which has several disadvantages (in size, elegance, performance, etc.). But if this has to be done with Image(url='http...), and that makes default behavior less surprising, perhaps we should do it.

The costs of this change:

• increased notebook size
• increased unnecessary b64 data in notebook
• increased cost of displaying images (b64 encoding / decoding)
• increased network traffic when displaying images / loading notebook
  • kernel downloads image, never caching
  • kernel sends b64 image to Browser, which is significantly larger than the original
  • circumvents browser cache of images from urls

The benefits:

• consistency between QtConsole and Notebook
• Notebooks more likely to be complete in offline viewing

[Carreau]

hum...
I'm totally unable to display jpeg in the qtconsole...

from IPython.core.display import *
Image('http://github.enthought.com/mayavi/mayavi/_images/example_potential_ipython.jpg', embed=True)

Out[3]: <IPython.core.display.Image at 0x10ebdde50>

Any idea why ? I tried specifying the format='jpg' without luck.