The end of section 6.1 actually covers this, but never mind.thanasispap wrote:Hi,
I want to ask whats the process for upscaling/downscaling to the required resolution (binning I suppose but 2x2 or what?).
I have noticed that when I change resolution to 640x480 the full FoV remains.
I read the docs, but my questions still remains...
(http://picamera.readthedocs.io/en/relea ... mera-modes)
The algorithm is not infallible, but scores each sensor mode against the requested mode, with the main criteria being:
- Must be able to provide the requested frame rate if at all possible.
- The sensor mode flags must allow the requested mode type. This is why the full res mode is always selected for stills captures, as that is the only mode that has the still mode flag set.
- Diff between requested width and height against the sensor mode width and height. Score against the mode if it needs to scale the sensor image upwards.
- Diff in the requested mode aspect ratio vs the sensor mode aspect ratio.
You don't give full details, but I'm assuming you've not changed the default frame rate so it'll either be a fixed 30fps, or a variable 1-30fps (used for stills modes). That eliminates modes 6&7 as they have a frame rate range of 40-90 (or possibly 120) fps.
Scoring on aspect ratio will give modes 1&5 a lower score as they are 16:9.
Scoring on resolution will therefore choose mode 4 at 1640x1232 as being closest to 640x480 without upscaling.
Mode 4 has a full FOV, so that is what you see.