I've never liked the way Hero handles light creation. Images (only to create light) strikes me as an awful kludge - you aren't creating an image of anything, just letting people see what's already there. So, I created rules to facilitate this. They sort of expanded to codify ambient conditions for light/darkness and sound.
Change Environment
CE can now be used to change light levels. It costs 3 points for +/- one light level. CE may not reduce the light level below zero.
Images
Light Images now rely on ambient conditions to be perceived. They do not create light, and may require a PER roll to detect in adverse conditions. Sound Images default to a Sound Level of 6, but may be changed at will.
Advantage: Easily Perceived (+1/4) – An Easily Perceived Image can be detected regardless of the ambient conditions (visible in a dark room or audible in a noisy crowd).
Limitation: Obvious (-1/2) – an Obvious Image is automatically recognized as an image without a Perception roll.
Effects on Perception
Dark conditions give a -1 Sight PER modifier for every light level below 4. If the light level 0 or less, no sight perception rolls may be made (pitch blackness). Extremely bright conditions give a -1 penalty for every light level above 6. Some types of Sight Flash Defense may reduce this penalty at the GM's discretion.
Sample Light Levels
Cave Interior: 0
Moonless Night: 1
Moonlit Night: 2
Dim Interior Lighting: 3
Normal Interior Lighting: 4
Cloudy Day: 4
Full Sun: 6
Noon in the Sahara: 7
Listening for a quiet sound (less than the ambient sound level) incurs a -1 penalty for every sound level the sound is below ambient. Conversely, there is a +1 bonus for every level the sound is above ambient.