You must access these functions through the Edit menu:
Clementine images were prepared with their own contrast and brightness settings. Desktop and laptop screens have different display settings too. Chances are you will want to adjust the simulation to suit your personal taste. The USGS texture "shaded relief" map has a constant illumination that is not suited for the change in brightness towards the terminator.
Remember that the display is NOT photometric! The eye takes in a wide dynamic range of brightness, from the sunlit surface to the reflected earthshine, something that an image cannot do without artificial adjustment. In order to produce an image that appeals to you, Lunar Calculator can adjust the overall brightness and contrast, add earthshine, and lower the brightness towards the terminator.
The maria are dark lava beds compared to the much brighter rocky highlands in the south. A contrast of 100 will give the original Clementine value. Higher values make the bright areas brighter and the dark areas darker. Lower values of contrast narrow the range from dark to bright. You can also shift the brightness of the entire image up or down.
Terminator shading
Anyone who has taken pictures of the Moon knows that the sunlit limb is significantly brighter than the terminator region. If you get nice craters, the limb is overexposed, but if the limb is done just right, the terminator region is too faint:
You can easily see how the brightness drops off considerably towards the terminator. Lunar Calculator can simulate this. However you must note that this simulation is for aesthetic appeal only! The eye reacts to light differently than the objective camera.
You can modify these factors on either the Clementine or USGS texture "shaded relief" images.
Earthshine is added to the "dark side". From there, you need to "step up" in brightness to the sunlit side of the terminator. Without a step change at the terminator, the image is not at all realistic. Then the brightness needs to increase to full illumination. Theoretically, there is a continuous change from points on the terminator to those where the Sun is overhead. Additionally, the factor changes with latitude. Practically however, it's tough to notice the change after about 30 degrees, so I've set the default transition zone to 30.
In total, the three factors, earthshine, step up, and transition add up to 100% of a point's brightness. The slider bars are set up to prevent a point in the transition zone from being brighter than what it would be outside. Therefore, if the earthshine is set at 60%, the step up and transition can only add up to 40%. The latter two can each be adjusted, but they are tied together to total the remainder, in this example 40%.
Click on "Apply changes" to see how your settings affect the final view. You can choose the "phase" of the Moon by adjusting the value for solar longitude. 0 degrees is full Moon, 90 is First Quarter, and 120 is waxing crescent.
Clicking "reset" for the terminator shading or the contrast/brightness will return the values to what they were when you first opened the window.
You can choose to have no terminator shading or contrast and brightness modifications by unchecking the approprioate boxes. When you click OK, the values will be transfered to the main program, and will be saved in the configuration file when you exit the program and save the settings. If you click "Cancel", the original values on startup will be used.
Lunar Calculator will run faster if the earthshine is set to zero, because it can skip the retreival of brightness information and calculation of earthshine (for either Clementine or USGS images). Adding terminator shading and contrast/brightness adjustments adds only a small amount of computation time compared to retrieving the brightness of the pixel at each point on the lunar surface.