Fingerprint reader

Not to discourage you, but I'm not so sure that would work, assuming you mean to "scan" the user's fingerprint in order to ID them.

Obviously putting your finger on the screen will do nothing, and placing your finger directly on the camera lens would not work either as the camera would see nothing due to no ambient light.

Beyond that, most phone cameras cannot focus well at very close distances. At the closest range that it would focus, I doubt there'd be enough detail to tell one fingerprint from another.

If you mean taking exisiting images of prints and compare them looking for a match... well, I wouldn't really know where to begin but I suppose that could conceivably work. Although you may be better to have the processing done on a server somewhere rather than the phone. I know that technology does exist, but I would guess it's pretty complex stuff.

I believe he's talking about phones that have built in scanners, I'm pretty sure I've seen at least one.

Sent from my DROIDX

Well now... That would be different. Now I feel old and out of the loop. I didn't realize they had devices with those built in now.

Ya, instead of just a passworded lock screen the user can unlock the phone with his fingerprint. I suppose this could be a useful feature in an app where u want to secure things. However I imagine this is a very limited market

Sent from my DROIDX

Yes, Like the Motorola Atrix 4G and such.
I have a client that needs such security. I have written a signature capture function, but it does not encrypt nor reliably attach the signature to his data/documents.
Thanks,

My wifes Atrix 2 has this ability (which I didn't know about when purchasing). Gave it a go and locked it to my finger - it asks you to scan you left and right index finger (sure its those) and also a code in case it fails or your finger drops off. Worked each time for me without needing the code, maybe someone could have an app in mind that would use it - in the android sdk downloader it does show ATRIX2 by Motorola Mobility Inc under 2.3.3 (API 10) so maybe thats the starting point...ok gone further........

You need to create an account at developer.motorola.com in order to download the sdk, however read https://developer.motorola.com/docstools/library/writing-fingerprint-enabled-apps/ for more info, another registration is needed for the provider of the fingerprint reader. Looks a bit limited in that you can check the fingerprint scanned is the owner(s) of the phone and not much else - however a detailed read may prove otherwise.

hello.

As i read this i think if you want to make an app with fingerprint scanning it might be better to think about external hardware.

I believe it might be relatively easy to build something with this.
Fingerprint Slide Scanner - SparkFun Electronics

and using an arduino for example.
I know that there is some stuff to interface an android phone with an arduino.