The LCD contrast mode can be used to change the visibility of characters observed on the LCD.
The LCD contrast can be adjusted by entering the contrast adjustment mode by double pressing the button on the front panel. Once the unit is in contrast adjustment mode, pressing the button will decrease the contrast by one level (lightening the display). There are 5 different contrast levels, and the LCD will cycle from the lightest to darkest if the button is pressed.
To exit the contrast adjustment mode, simply double press the button on the front panel again. The button will return to normal operation after this.