Google Now on Tap now lets you search via image and text

Google Now on Tap has just been updated with a few significant features, the changes will now let you select certain text for specific search terms, conduct real-time image searches using the camera app, and make simple image searches, which vastly improves on what Google Now on Tap was previously capable of.

If you received the update today, you should be able to find the new feature on the Now on Tap bar, denoted by the finger icon at the bottom.