a simple question: do you to download dozen of HD pictures on a single web page on mobile?

also you need to increase not to decrease the memory limit
you can generate resized pictrues locally ; many threads about that

mmh yeah don't know why Google, facebook ect didn't thought that too...
let me remind you that the picture is resized only once, that's all, not for each visitors

Hi mathias,

If you use Piwigo default settings for photo sizes, the "multiple sizes" cache should not take that much space, compared to your original photos. If your photos are 10MB each (which is very common nowadays), an XXL will take less than 1MB, M-size around 300KB (these are approximate values)

If you don't like the multiple sizes, you can limit this features: go to [Administration > Configuration > Options > Photo sizes], and uncheck all sizes but M.

Multiple sizes are absolutely necessary for a photo manager like Piwigo. Maybe you don't need the 9 sizes, but at least a thumbnail and the M size (equivalent as Piwigo prior to version 2.4).

Now about the memory required, I think 128MB is very small. The ImageMagick "convert" script may need more than that, depending on the size (in pixels) of your original photo.

If you upload very small original photos (smaller than the configuration of the M size) then Piwigo won't generate a M size and display directly your original photo.

http://piwigo.org/forum/viewtopic.php?id=26195 can be used to disable multiple sizes completely.