I've been told about car's plate image database that are avaliable on the web for free download to develop image processing and automatic number plate recognition algorithms, does anyone have a link to download or at least some keywords to search on the web?
If it's not legal or is there any ethic issues i would thank if you notice me.
It's perfectly legal to do so, as long as the images are CC (Creative Commons) licensed, or you have permission of the website owner to do.
A quick search for number plate image database
yields some results: