Re: [Matplotlib-users] display pixels values on the backends

[Jae-Joon L. <lee...@gm...>]

On Mon, Aug 24, 2009 at 1:48 PM, Xavier Gnata<xav...@gm...> wrote:
> Hi,
>
> I have already asked about that but I'm back once again :)
>
> The way I use matplotlib may be a corner case:
> I'm often looking at large (4k x 4k) images and I do want to see the
> pixels values moving the mouse over the display.
> imshow does a great job but all the backend only display "x= y=".
> I would love to see "x= y= Z=" (or "value="...call it the way you want ;))
>
> What is the best way to do that?
> imshow is great because there is nothing to connect to see x and y
> values on the backend.
> I need to code something as simple as imshow to get also the pixel values.

The easiest way I can think of is to override Axes.format_coord
method.  A pseudo code might look like below

def report_pixel(x, y):
   # get the pixel value
   v = get_pixel_value_of_your_image(x,y)

   return "x=%f y=%f value=%f" % (x, y, v)

ax = gca()
ax.format_coord = report_pixel

The code will become more complicated if you want to support multiple images.
This solution is far from elegant, but maybe the easiest one.

-JJ

>
> Is there really on way to get that as a new option in imshow? at least
> in one of the backend (as a starting point)
>
> Best Regards,
> Xavier
>
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