Epson ES-1200C - Manual (Page 78)

It is better to use darker settings for line art, or faint original
images, and to use lighter settings for darker original images.
The brightness can be combined with any other function.
The graph below shows the differences between the brightness
settings when the gamma correction is set for the CRT Display
A setting.
Data
Normal (center)
Darkest setting
Lighter
image input
Appendix A-7