On Thu, 2007-09-13 at 17:31 -0400, John Kua wrote:
> Roman,
>
> I recently went through this problem. It seems that using setpwc to disable
> AGC is pointless, because the next time the camera is accessed, as far as I
> can tell, it defaults back to AGC on. This, however, is not a pwc problem,
> nor is it really a setpwc problem. Because the AGC setting resets every time
> you open the camera for access, you have to disable AGC, set your desired
> gain AND capture the images you want in one session.
>
> In other words, the program you use to capture your images has to set the
> gain itself.
oh.. thank you a lot for that information. this made a lot things
clearer for me.
roman
> -John
>
> -----Original Message-----
> From:
> On Behalf Of Roman Haefeli
> Sent: Thursday, September 13, 2007 5:19 PM
> To:
> Subject: [pwc] automatic gain control
>
> hello
>
> i plan to use my SPC 900NC for an artistic project. therefor i want to
> make a comparison between a buffered background image and the realtime
> image in order to remove the background of the image.
> however, this only works, if i manage to keep the gain stable. according
> to 'setpwc -h', i am supposed to set a value for automatic gain control
> by using "setpwc -g <0-65535>". actually, i am not quite sure what
> "setting the automatic gain control" means. i mean, why is there a user
> settings, when it is done automatically anyway?
> i had the impression, that this setting doesn't affect anything or it
> gets overwritten instantly by the automatic gain control. i found out,
> that whenever i access the cam through setpwc (or mplayer or
> whatsoever), the gain is adapted.
>
> doing 'setpwc -p', while pointing the cam towards a light, i get:
>
> Automatic gain control: -2502
>
> doing the same while pointing the cam into the dark, i get:
>
> Automatic gain control: -25815
>
> to sum it up:
> the option '-g' doesn't show any effect at all.
> the values seem to be in the negative range, not in the range 0-65535,
> as mentioned in the help.
> is this a bug? (of pwc or setpwc?)
> is there some way to get rid of automatic gain control?
> is this something the driver does or the camera itself?
>
> i am using:
> pwc-10.0.12-rc1
> setpwc v1.1
>
> thanks in advance
> roman
>
>
>
>
>
>
>
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