gspca_sunplus: problem with brightness control

gspca_sunplus: problem with brightness control

[Németh Márton]

Hi,

I am using a "Trust 610 LCD Powerc@m Zoom" device in webcam mode
(USB ID=06d6:0031). I am running Linux 2.6.31-rc7 updated with the
http://linuxtv.org/hg/v4l-dvb repository at version 12564:6f58a5d8c7c6.

When I start watching to the webcam picture and change the brightness
value then I get the following result. The possible brigthness values
are between 0 and 255.

for i in $(seq 0 255); do echo $i; v4lctl bright $i; done

0: average image
 |
 | lighter images
 v
127: the most light image
 |
 | "jump" in brightness
 v
128: the most dark image
 |
 | lighter images
 v
255: average image

It seems to me that the values 128...255 are really negative numbers, so
the possible range should be between -128...127 (two's complement representation)
in case of this webcam.

Note that the contrast and color controls does not have any jump in
the range 0...255.

Regards,

	Márton Németh

Re: gspca_sunplus: problem with brightness control

[Jean-Francois Moine]

On Sun, 30 Aug 2009 08:22:46 +0200
Németh Márton <nm127@freemail.hu> wrote:

> I am using a "Trust 610 LCD Powerc@m Zoom" device in webcam mode
> (USB ID=06d6:0031). I am running Linux 2.6.31-rc7 updated with the
> http://linuxtv.org/hg/v4l-dvb repository at version
> 12564:6f58a5d8c7c6.
> 
> When I start watching to the webcam picture and change the brightness
> value then I get the following result. The possible brigthness values
> are between 0 and 255.
	[snip]

Hi Márton,

I fixed this problem in my test repository. As I did some other changes
in sunplus.c, may you check if everything works for you?

Regards.

-- 
Ken ar c'hentañ	|	      ** Breizh ha Linux atav! **
Jef		|		http://moinejf.free.fr/

Re: gspca_sunplus: problem with brightness control

[Németh Márton]

Hi,

Jean-Francois Moine wrote:
> On Sun, 30 Aug 2009 08:22:46 +0200
> Németh Márton <nm127@freemail.hu> wrote:
> 
>> I am using a "Trust 610 LCD Powerc@m Zoom" device in webcam mode
>> (USB ID=06d6:0031). I am running Linux 2.6.31-rc7 updated with the
>> http://linuxtv.org/hg/v4l-dvb repository at version
>> 12564:6f58a5d8c7c6.
>>
>> When I start watching to the webcam picture and change the brightness
>> value then I get the following result. The possible brigthness values
>> are between 0 and 255.
> 	[snip]
>
> I fixed this problem in my test repository. As I did some other changes
> in sunplus.c, may you check if everything works for you?

I tested the version "12663:7f68f4e03299" from
http://linuxtv.org/hg/~jfrancois/gspca/ . The picture is still OK, the
brightness, contrast and color contrast are working correctly now as
expected. I have done the tests with "Trust 610 LCD Powerc@m Zoom" device
in webcam mode (USB ID=06d6:0031).

Thank you for your work!

Regards,

	Márton Németh