each_channel decorator

[Tony Yu]

On Fri, Oct 19, 2012 at 4:35 PM, Stéfan van der Walt <stefan at sun.ac.za>wrote:

> On Wed, Oct 17, 2012 at 6:48 PM, Tony Yu <tsyu80 at gmail.com> wrote:
> > I'm not really sure how a utility function would work. Wouldn't you need
> to
> > provide at least 2 utility functions when converting to LAB:
> >
> >     image, ab = prepare_rgb(image)
> >     # ... code to generate `filtered_image` from `image`
> >     filtered_image = finalize_rgb(filtered_image, ab)
>
> A utility function would simply take an image and apply the specified
> filter to all its layers (which are pre-and post-converted in some
> way), e.g.
>
> apply_to_rgb(image, filter)
>
> > Basically, that's all to say that I think a decorator makes a lot more
> sense
> > in this case.
>
> But it does mean introducing a flag.  I'm debating which is clearer
> and more explicit:
>
> apply_to_luminance(image, filter)
>
> vs
>
> filter(image, rgb_behavior='luminance')
>
> (with the caveat that rgb_behavior has to be documented in each and
> every filter function--and that we have to figure out a way of
> preserving signatures and docstrings with decorators)
>
> Stéfan
>


Oh, I see: Utility functions for users to apply a grayscale filter to their
color image. I was thinking of utility functions that allows us to add
RGB-handling to scikit-image functions (so that it just works without the
user needing to think about it).

Personally, I'd prefer RGB images to just work. For most filters, there's
probably a preferred way to handle an RGB image (e.g, Lightness channel,
RGB layers, grayscale), and that would just be the default (I guess the
*preferred* way may not always be obvious).

I agree that documenting the extra filter parameter could be problematic. I
guess that the decorator could inject that into the filter's docstring, but
that's probably too magical. We could make it a hidden parameter and
provide utility functions that just change the default behavior.

-Tony
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/scikit-image/attachments/20121019/b9a483ba/attachment.html>