[Gegl-developer] tile size in filters

[Dierk Fröhling]

Hans Petter Jansson wrote:
> On Thu, 2008-10-09 at 11:08 +0200, Dierk Fröhling wrote:
> 
>> I need to handle all pixels of an image in one tile for my new filter.
>> The problem is that every pixel in the filtered image should depend on
>> values from all other pixels...
>> I tried out different things from other (example) filters (including the
>> bounding box stuff) but my image is always split into several tiles.
>> Is there any way to tell the gegl infrastructure to use the whole image
>> as one tile as input pad?
>> The bounding box stuff doesn't work especially because the size of
>> images can differ.
>> I know that this could lead to memory problems with really big images...
> 
> I wrote a color reduction filter that does Floyd-Steinberg dithering,
> where each pixel depends on all previous pixels (the bottom-right pixel
> depends on the entire image). It should be among the workshop filters.
> Maybe that'd be useful to look at.

This worked up to a certain size of images - but with an image with 3112
x 4200 pixels I get this message from gegl:

** Message: unable to write tile data to self: No space left on device
(-1/131072 bytes written)

There is enough space in my /tmp directory and all other possible
working directories for gegl - 2GB of memory should be enough as well...
It's not that my filter won't work at all with these big images - but
only in parts. It seems that gegl splits it into tiles again...

Dierk