[OSM-dev] NOT-saving empty Mapnik tiles
marqqs at gmx.eu
marqqs at gmx.eu
Fri Aug 12 18:51:18 BST 2011
Hi Igor,
thank you, this link is very helpful!
> um, what is your definition of "empty" exactly? Is it "all pixels are
> transparent"? Or is it "all pixels are of the same color"? Or is it "all
> pixels are of color X"? I don't think there's an Image.is_empty()
> because "empty" means different things to different people.
Sorry, my fault. :-)
I want to determine if an image has transparent pixels only. If yes I would like to dispose it because nobody could see it anyway.
Would save disk space - and inodes...
-------- Original-Nachricht --------
> Datum: Fri, 12 Aug 2011 19:36:28 +0200
> Von: Igor Podolskiy <igor.podolskiy at vwi-stuttgart.de>
> An: dev at openstreetmap.org, marqqs at gmx.eu
> Betreff: Re: [OSM-dev] NOT-saving empty Mapnik tiles
> Hi Markus,
>
> > Is there a function like im.is_empty() ?
> um, what is your definition of "empty" exactly? Is it "all pixels are
> transparent"? Or is it "all pixels are of the same color"? Or is it "all
> pixels are of color X"? I don't think there's an Image.is_empty()
> because "empty" means different things to different people.
>
> There are different ways to do that depending on the definition. You can
> loop over the image pixels with im.getdata() and check some property of
> an image, or you might want to take a look on im.getcolors() dictionary
> which tells you how often a color occurs in the image. There's PIL
> documentation for all the Image methods here: [1].
>
> If you have difficulties writing that down in Python, I'd be happy to
> help - just drop me a line here.
>
> Bye
> Igor
>
> [1] http://www.pythonware.com/library/pil/handbook/image.htm
More information about the dev
mailing list