ICO container

[Chef]

I'm making a video library app and want to view my videos as thumbnails of course, where each video file has a thumbnail image.
After some digging in the forum I didn't find a descent way of downsizing a common image file (jpg,png etc) with some visual effects like centered or drop/background shadow.
So I decided to have my thumbnail images in an ICO file where I can switch view size quickly by accessing a certain size in the ICO file.
But I can't access images larger than 256x256 unless the size I'm trying to access is the only image in the ICO file.
Trying to view any size bigger than 256x256 will just view a stretched 256x256.

Here is a test script and ICO file
https://db.tt/5Ix6th74

Any idea?
Thanks

[SL5]

for downsizing you sould proably add a thirtd-party app