Here is an image gallery that shows the high definition video surveillance quality of the Viewtron DVR viewer app for iPad. At CCTV Camera Pros, we have a Viewtron VT-HD404 DVR connected to 4 HD-SDI CCTV cameras and 4 traditional CCTV cameras.
If you are not familiar with HD-SDI cameras, they use the same RG59 or RG6 coaxial cable as traditional CCTV cameras but they are able to support full 1080p resolution. They also require an HD-SDI compatible DVR to work. Some Viewtron DVR models are hybrid which means they work with both HD-SDI and traditional CCTV cameras. If you would like to learn more, there is an article here that explains further and explains HD-SDI vs. CCTV resolution.
In the above views, channels 1-4 are HD-SDI cameras and 5-8 are regular CCTV (this can be seen in the 8 camera view image). In addition to iPad, the Viewtron iOS app also works great on iPhone and iPod Touch. There is also a Viewtron DVR viewer app for Android that works on both phone and tablet format Android devices.