Security Feature - Optically Variable Ink

Optically variable inks (OVI) are very expensive inks applied on banknotes as a security feature. So far, only the 1000 peso bills have this. There are two versions of OVI printing on the 1000 peso banknotes. The image above shows the newer 'improved' version on top of the older one. The former has more coverage and its color varies better. This is an excellent security feature because counterfeiters will need a lot of effort and money to replicate it.

So why are they called optically variable inks? Tiny flakes of color-shifting film are incorporated in the intaglio ink. Thus, prints of OVI change color when viewed from different angles. The pictures below show how the 1000 figure changes from green...

to blue... Or does it?