Member Discussion

Is It Better To Do Digital Zoom Processing On The Camera Or The Client?

Does anybody even use camera-side zoom? It would seem to have several disadvantages, not least of which would be that you end up recording only the zoomed FOV...

Is camera-side digital zoom usually applied to all streams, individual streams or individual connections? Does everyone use the same basic scaling algorithms or are there significant differences?

Is the correct formula actually Total Zoom = max optical zoom X max camera side zoom X max VMS zoom? .....Ok I'm kidding about that one! ;)

What do you mean by camera side zoom? I ask because it's not a term I hear people / manufactuers zoom.

There's cropping, e.g., what Sony evarifocal is doing. Is that what you mean?

I've only seen camera-side zoom in reference to digital zoom on some PTZs.

You know when a camera spec says 4x digital zoom for instance. Who enforces that 4x limitation? It has no effect on the local zooming of the VMS.

In ONSSI there is a checkbox "digital zoom" for each stream shown on screen. When checked, using the scroll wheel causes the VMS to run the zoom processing on the PC. If unchecked then ONSSI driver may (depending on camera and driver) pass a zoom command to camera to process zoom on the camera. That type is limited by the camera capability.

So what are the correct terms for these two zooms? Or am I not making sense?

To the extent that camera manufacturers spec digital zoom, perhaps they mean for their own web client interfaces. I am not really sure what justification they use as I've always seen it as a nonsesnse spec.

Btw, out of curiousity, I checked Axis specs. They list 'Digital PTZ' on all but do not include any zoom number (see specs for M30, P14 and Q16).

Also, related Digital Zoom Tutorial.

I will say this, and not to encourage this bad practice, but a lot of attendees in our camera course get repeatedly tricked by differences in spec'd digital zoom levels mistaking a camera that, e.g., claims 16x digital zoom is better than one that claims 12x digital zoom.