Screen Brightness problems

First SL went on perfect and i have had no software issues, however there seems to be a problem with brightness. The screen looks dimmer than normal i have tried adjusting brightness but it is all the way to the right. I have tried loading a new desktop picture but they all seems dimmer, i have searched for posts and it seems to be something wrong with the colour profile but i do not understand it correctly can anybody help with this problem the screen problem was not there before cannot understand it