Adjusting brightness/contrast with psychtoolbox

Hi all


I'm attempting to run an experiment displaying faces on the screen in an fMRI setting. The problem is our scanner's image quality is really washed out. The black background appears grey and the surfaces of the faces appear very pale. This makes it very difficult for the participants to distinguish between each face and definitely has negative implications for the quality of our data.


The scanner facility has told us they cannot modify gamma/brightness/lumination settings through their system and we have to use MATLAB to adjust it. 


I've been trying to look for Screen functions like ConfigureDisplay, or CLUT modifying parameters, but none of them are modifying the images onscreen. 


Looking for help on how to specifically do this.


Thanks!

If you set background to black, and it shows gray on the display, then there is a problem with the display system. I don't think it is something you can fix in Matlab.
-Xiangrui