A static example image served from the following address (relative to your digilib context):
servlet/Scaler?dw=200&dh=200&fn=/p0005.jpg
Notice the parameters: fn denotes the image path and filename (set in WEB-INF/digilib-config.xml), dw and dh the width and height (in pixels) of the reduced image to be transferred from the digilib servlet.