got it .. thanks ..
can we say "its an amazing picture" ?

When we say, "its an amazing picture", we have used a contraction of 'it is',

We show that by writing:
it's an amazing picture

Notice that " it's " has an apostrophe.

" its " is what we use - just like, 'his, her" - to show possession:
The dog was wagging its tail.

There is more about this on Grammar Monster at :
apostrophe