Sprites resolution for tablet game

I want to do a point'n'touch adventure game for Android/iOS and I draw in vector graphics at first so I can scale to any size, but will need to use pngs in C2.

My question is, what resolution should I work in, and what size my objects should be to allow some nice zoom in and out when pinching without pixellation?

Examples:

<img src="https://dl.dropboxusercontent.com/u/61894646/indoor%20try.PNG" border="0" /><img src="https://dl.dropboxusercontent.com/u/61894646/cavegold02.PNG" border="0" />

2048 x 1536

For better peformance:

Cut the pieces in tiles each 512x512 graphic files.

For zoom without pixellation:

Scale down a HD sprite in editor, yeah it's a trick.

http://powerupware.com/HTML5/zoompng/

Thanks Joannesalfa, I'll try these this week!

I do not believe cutting any images in to smaller tiles will improve performance. I'll believe it when I see a benchmark proving it. It could also cause you annoying seaming problems.

sved : I am not sure the size in editor thing works if you are using the low quality setting

Ashley : a funfact, I know the master system uses only 8x8 (or 8x16 if a certain setting is on) pixels sprites, so to have a bigger one, you'd have to cut them and assemble them back in 8x8 pieces

Ashley: Understand, slicing makes no difference and I'm glad it doesn't, i'll go for big images!

Aphrodite: I don't really get it, you mean it won't work when exported? I'm trying to estimate the final resolution of characters on screen to be able to know what sizes my limbs should be in .png for Spriter... (and I hope I make sense ^^)

sved : I meant if the "low quality" option of C2 is used, but I don't think you use it anyway, so It shouldn't be a problem.

It's used to reduce choppy performance in old devices.

It depends on the exporter if we use 512 x 512 it could generate 2048 x 2048 image in sprite sheet, otherwise we use 510 x 510, it would generate 1024 x 1024 image in sprite sheet.

The smallest image makes decent performance on old devices.