On Tuesday 28 August 2007 11:32, Dr. techn. Alexander K. Seewald wrote:
> On Tue, Aug 28, 2007 at 01:14:51AM +0200, Laurent Pinchart wrote:
> > There are two things to implement in Linux to get something similar. The
> > first one is to implement manual focus into the driver. This shouldn't be
> > difficult and I'll have a go at it. The second one is much more complex.
> > You'll have to come up with a userspace image processing algorithm to
> > compute focus values from the video. I have no experience with that.
>
> I'll visit my brother today, who happens to have an WinXP machine
> lying around. Perhaps the manual focus will stay in the same setting even
> when disconnected, which would instantly solve my problem.

It probably will (although I'm not sure about it).

> If you need some USB traces during manual focus control by the windows
> application, just let me know (& tell me which tools to use, I've never
> done this before ;-)

This shouldn't be necessary, I should be able to get the necessary 
information. Thanks for the offer anyway.

> For my application, manual focus control would be sufficient. But I'll
> see whether there are some published approaches in the image processing
> literature for autofocus which could be ported... the trick is
> probably to get a fast "in-focus" estimate on each image and change
> the focus in the right direction until it reaches a maximum value.

A high-pass filter followed by a simple pixel sum could be a simple estimate. 
Might not be good enough, but worth a try.

Best regards,

Laurent Pinchart
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