Change launcher icon opacity/brightness

You can do this with a new tool that several users here on Ask Ubuntu have made. Its called Unity Tweak Tool. It's still in early development but it is very stable from my testing.

To install it:

sudo add-apt-repository ppa:freyja-dev/unity-tweak-tool-daily  
sudo apt-get update && sudo apt-get install unity-tweak-tool  

Now open the dash and search for "Unity Tweak Tool". It looks like this:

Open it up and navigate to Launcher.

From there you can:

1. Change the transparency of the launcher

2. Change the color of the laucnher

3. Auto-hide the launcher

4. Or change the background for applications (This is closest to what you want I think)

   

Another suggestion is changing your icon theme under Icons.

You need to note however, you can't very well change icons of other applications.

Brightness is relative, but I got them this dark:

For certain icons, like the software center, you might have to change the actual icon, wherever the system stores it.

With MyUnity (http://www.uielinux.org/myunity) you can change these settings for the launcher:

1. color
2. transparency
3. icon size
4. icon "backlights"
5. hide animation
6. behavior by default (auto-hide or not)
7. show device icons

Themes and icon themes can be also changed.

Check the demos in their webpage.

edit: Perhaps the best strategy is to adjust the appearance of the launcher (backlights, auto-hide, color) and select a more pleasing icon theme (any suggestion?).