Why is the picture washed-out whitish (i.e. like an overexposed photo)?
Probably because your Radiance image contains true values of luminance or illuminance and not scaled to your output device. You can adjust the exposure (which does not affect the underlying values, just the display for your monitor) or use pcond to scale pictures to your output device (which will “flatten” the values). For more information on pcond, please read the pcond man page.
