Hey Jane,
What you're looking for is the IMAQ Cast Image VI. This allows you to specificy the type of image you would like to cast as, such as Grayscale (U8). One thing to pay attention to when using this VI is the Number of Shifts input. The default value was making the image purely white, but when you increase this value, you will able to get a more distinct picture. You can play with the input ranging from 1-8 to determine the what gives you the best image.
Hope that helps.
