To use preview for glass, you need to sideload the apk file onto Google Glass. Here's a brief reminder on how to sideload.
Put Glass into Debug Mode
From the "ok glass" screen...
- Scroll "back" to Settings. Tap.
- Scroll "forward" to Device Info. Tap.
- Scroll "forward" to Turn on Debug Mode. Tap.
Load the app onto Glass
- Connect Glass to your computer via USB cable.
- Get the
Android SDK and install
- Download the Preview.apk
- Go to the directory with the APK file and type: adb install Preview.apk
If you need more explanation, please refer
this tutorial as well. (this site is not related to our app, so please don't ask questions about
Preview on the site)