I know this problem has been bugging many Skype users on Linux (especially on Ubuntu), so I want to share my fix for this problem. 
I have a Chicony Electronics Co., Ltd 2.0M UVC Webcam / CNF7129 as my default webcam. It works great on Ubuntu Karmic and Lucid especially when I use Cheese to take videos or snapshots despite the lighting conditions. However Skype seems to dislike my webcam, It works fine on finely lighted areas and especially in the morning and afternoon but when it gets dark or there’s a limited light source the webcam video gets very “abnormally” dark!
After searching the web for possible fixes it seems the only way to resolve this problem right now is to manually configure the webcam. To do this, first I had to install luvcview .
Luckily you can download and install it through synaptics or open a terminal and type:
$ sudo apt-get install luvcview
After completing the installation, you have to close any instance of Skype then on the same terminal type:
$ sudo luvcview
It will open up a window displaying input from webcam, on the lowest part of the window you will see the configuration buttons.
Now we set brightness to max! click on the first button on the left, keep clicking on it until you reach maximum brightness. you can also set contrast, sharpness, saturation, exposure levels, etc. here.
Any changes you make here will affect the default behavior of your webcam. Do the necessary changes you want but make sure brightness is set to max, after that close the window then open Skype.
Skype video should be brighter now.
Please let me know if you have a better solution.
You are my hero! Thanks so much for posting this.
This was a great workaround for me on an Eee 1000HE running Ubuntu Lucid 10.04 + Skype (CNF7129)
https://bugs.launchpad.net/ubuntu/+bug/542042
https://jira.skype.com/browse/SCL-566
Not just brightness, but changing “flicker” to 50Hz also improved light reception IMO:
SDL information:
Video driver: x11
A window manager is available
Device information:
Device path: /dev/video0
Stream settings:
Frame format: YUYV (MJPG is not supported by device)
Frame size: 640×480
Frame rate: 30 fps
Control name:Brightness already has max value:64
Current light frequency filter: 50Hz
I’m glad I was ale to help you out.
Never really thought anyone actually read my rants. 
and thanks for pointing out the benefits of adjusting “flicker”.
Worked like a charm great post!
i just hope they fix this soon
people are stupid
I tried this fix and it’s made things worse in some ways. The webcam now seems to adjust itself to a completely black screen below a certain threshold. Ive tried uninstalling the luvcview but the problem remains.
How do it put it back to how it was before
It seems setting flicker to “No Flicker” or “60Hz” causes the problem. Try setting it to 50Hz.
@Tome: Try installing luvcview again and run it from terminal, then put your terminal and luvcview interface side by side (any luvcview changes you do is shown in the terminal complete with current value and max value). Try tweaking around it some more and see what values produce optimal results.
Also, try out jackie’s settings (I believe my settings are almost the same as his/hers). If it still won’t work try out guvcview, I believe it is available in synaptics too.
I will try and replicate your problem once i get back. Haven’t used skype in a while.
I would also suggest to look for any recent bug reports on launchpad.
i was looking for a way to get my skype video brighter. i went through many posts and this was the most helpful. thank you!
Thank you for finding this fix it works like a charm.
Hey, this fix was awesome. worked like a charm. Thank you for posting it.
thanks alot man…….it helped alot…Thank you for posting it.
Your hint seemed promising but also the luvcview-window is completely dark on my machine. clicking in the lower part of the window gives errors on the console:
> ioctl querycontrol error: Invalid argument
> Set Brightness up error
Any suggestions?
laptop with webcam & other usb webcam
How to choose wich webcam to set with luvcview? It works only on my laptop’s webcam but I usually use the other one.
thanks