backlight and filters - algorithms needed

[Henry Bruce]

> I recently compared the output of our driver with the m$-stuff and found
> the following obvious difference. There is a 'backlight' option and some
> 'filters (50/60Hz)' that one can switch on/off in the m$-video panel. The 
> first one is useful in dark scenes. In case of compressed mode the image
> looks less grainy. The second one eliminates horizontal stripes that seem
> to occur during exposure changes. Has anyone an idea what kind of image
> processing filters those are?

These are no filters as such, just variations in how the automatic exposure 
controller (AEC) can be configured from the driver. Note that the AEC runs in 
firmware, so you have limited control on the way it operates

The backlight option (as in other cameras) doesn't use the full image to 
calculate the exposure value - just the bottom part of it. As you would 
expect, this option should be used when the subject is lit from behind.

The horizontal stripes are caused by mains lighting and are avoided, rather 
than cancelled. To do this, the driver must know if it is working in a 50 or 
60Hz environment. Details of how to set this up are in the developer's guide, 
but it is a tricky business.

Hope this helps.


Henry Bruce
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