Re: [Matplotlib-users] plotting large images

[Michael D. <md...@st...>]

On 08/27/2013 09:49 AM, Chris Beaumont wrote:
> I've been burned by this before as well. MPL stores some intermediate 
> data products (for example, scaled RGB copies) at full resolution, 
> even though the final rendered image is downsampled depending on 
> screen resolution.
>
> I've used some hacky tricks to get around this, which mostly involve 
> downsampling the image on the fly based on screen resolution. One such 
> effort is at https://github.com/ChrisBeaumont/mpl-modest-image.

It looks like this wouldn't be too hard to include in matplotlib.  I 
don't think we'd want to change the current behavior, because sometimes 
its tradeoff curve makes sense, but in other cases, the "modest image" 
approach also makes sense.  It's just a matter of coming up with an API 
to switch between the two behaviors.  Pull request?

Cheers,
Mike

>
> If you are loading your arrays from disk, you can also use 
> memory-mapped arrays -- this prevents you from loading all the data 
> into RAM, and further cuts down on the footprint.
>
> cheers,
> chris
>
>
> On Tue, Aug 27, 2013 at 6:49 AM, S(te(pán Turek 
> <ste...@se... <mailto:ste...@se...>> wrote:
>
>
>         You could look at whether or not you actually need 64-bit
>         precision. Often times, 8-bit precision per color channel is
>         justifiable, even in grayscale. My advice is to play with the
>         dtype of your array or, as you mentioned, resample.
>
>
>     thanks, this helped me significantly,  uint8 precision is enough.
>
>         Also, is it needed to keep all images? It sounds to me like
>         your application will become very resource hungry if you're
>         going to be displaying several of these 2D images over each
>         other (and if you don't use transparency, you won't get any
>         benefit at all from plotting them together).
>
>
>     Yes, I need them all .
>
>     To avoid it I am thinking about merging them into one image and
>     then plot it.
>
>
>     Stepan
>
>
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